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Introduction: Recent data are not available on ongoing CPR for emergency services with an onboard physician. The aim of the present study was to identify factors associated with the decision to transport patients to hospital with ongoing CPR and examine their survival to hospital discharge with good neurological status. Methods: An observational study based on a registry of out-of-hospital cardiac arrests attended to by emergency services with an onboard physician. All OHCA cases occurring between the 1st of January and the 31st of December 2022 were included. Patients receiving ongoing CPR during transport to the hospital were compared with patients pronounced dead at the scene following arrival of the care team. The dependent variable was ongoing CPR during transport to the hospital. The main characteristics and the neurological status of patients surviving to discharge were described. Results: A total of 9321 cases were included, of which 350 (3.7%) were transported to hospital with ongoing CPR. Such patients were young (59.9 ± 20.1 years vs 64.6 ± 16.9 years; p < 0.001; 95%CI: 0.98 [0.98; 0.99]) with arrest taking place outside of the home (151 [44.5%] vs 4045 [68.01%]; p < 0.001; 95%CI: 0.41 [0.31; 0.54]) and being witnessed by EMS (126 [36.0%] vs 667 [11.0%]; p < 0.001; 95%CI: 4.31 [3.19; 5.80]), whilst initial rhythm differed from asystole (164 [47.6%] vs 4325 [73.0%]; p < 0.01; 95%CI: 0.44 [0.33; 0.60]) and a mechanical device was more often employed during resuscitation and transport to hospital (199 [56.9%] vs 2050 [33.8%]; p < 0.001; 95%CI: 2.75 [2.10; 3.59]). Seven patients (2%) were discharged alive from hospital, five with ad integrum neurological recovery (CPC1) and two with minimally impaired neurological function (CPC2). Conclusions: The strategy of ongoing CPR is uncommon in EMS with an onboard physician. Despite their limited efficacy, the availability of mechanical chest compression devices, together with the possibility of specific hospital treatments, mainly ICP and ECMO, opens up the possibility of this approach with determined patients.

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Importance: Out-of-hospital cardiac arrest (OHCA) health care provision may be a good indicator of the recovery of the health care system involved in OHCA care following the COVID-19 pandemic. There is a lack of data regarding outcomes capable of verifying this recovery. Objective: To determine whether return to spontaneous circulation, overall survival, and survival with good neurological outcome increased in patients with OHCA since the COVID-19 pandemic was brought under control in 2022 compared with prepandemic and pandemic levels. Design, Setting, and Participants: This observational cohort study was conducted to examine health care response and survival with good neurological outcome at hospital discharge in patients treated following OHCA. A 3-month period, including the first wave of the pandemic (February 1 to April 30, 2020), was compared with 2 periods before (April 1, 2017, to March 31, 2018) and after (January 1 to December 31, 2022) the pandemic. Data analysis was performed in July 2023. Emergency medical services (EMS) serving a population of more than 28 million inhabitants across 10 Spanish regions participated. Patients with OHCA were included if participating EMS initiated resuscitation or continued resuscitation initiated by a first responder. Exposure: The pandemic was considered to be under control following the official declaration that infection with SARS-CoV-2 was to be considered another acute respiratory infection. Main Outcome and Measures: The main outcomes were return of spontaneous circulation, overall survival, and survival at hospital discharge with good neurological outcome, expressed as unimpaired or minimally impaired cerebral performance. Results: A total of 14 732 patients (mean [SD] age, 64.2 [17.2] years; 10 451 [71.2%] male) were included, with 6372 OHCAs occurring during the prepandemic period, 1409 OHCAs during the pandemic period, and 6951 OHCAs during the postpandemic period. There was a higher incidence of OHCAs with a resuscitation attempt in the postpandemic period compared with the pandemic period (rate ratio, 4.93; 95% CI, 4.66-5.22; P < .001), with lower incidence of futile resuscitation for OHCAs (2.1 per 100 000 person-years vs 1.3 per 100 000 person-years; rate ratio, 0.81; 95% CI, 0.71-0.92; P < .001). Recovery of spontaneous circulation at hospital admission increased from 20.5% in the pandemic period to 30.5% in the postpandemic period (relative risk [RR], 1.08; 95% CI, 1.06-1.10; P < .001). In the same way, overall survival at discharge increased from 7.6% to 11.2% (RR, 1.45; 95% CI, 1.21-1.75; P < .001), with 6.6% of patients being discharged with good neurological status (Cerebral Performance Category Scale categories 1-2) in the pandemic period compared with 9.6% of patients in the postpandemic period (RR, 1.07; 95% CI, 1.04-1.10; P < .001). Conclusions and Relevance: In this cohort study, survival with good neurological outcome at hospital discharge following OHCA increased significantly after the COVID-19 pandemic.

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The anatomical and functional characteristics of the elbow extensor muscles (triceps brachii and anconeus) have not been widely studied in non-human hominoid primates, despite their great functional importance. In the present study, we have analyzed the muscle architecture and the expression of the myosin heavy chain (MHC) isoforms in the elbow extensors in humans and chimpanzees. Our main objective was to identify differences in these muscles that could be related to the different uses of the upper extremity in the two species. In five humans and five chimpanzees, we have analyzed muscle mass (MM), muscle fascicle length (MFL), and the physiological cross-sectional area (PCSA). In addition, we have assessed the expression of the MHC isoforms by RT-PCR. We have found high MM and PCSA values and higher expression of the MHC-IIx isoform in the triceps brachii of chimpanzees, while in humans, the triceps brachii has high MFL values and a higher expression of the MHC-I and MHC-IIa isoforms. In contrast, there were no significant differences between humans and chimpanzees in any of the values for the anconeus. These findings could be related to the participation of the triceps brachii in the locomotion of chimpanzees and to the use of the upper extremity in manipulative functions in humans. The results obtained in the anconeus support its primary function as a stabilizer of the elbow joint in the two species.

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Cisplatin is one of the most widely used chemotherapeutic agents in oncology, although its nephrotoxicity limits application and dosage. We present the results of a clinical study on prophylaxis of cisplatin-induced nephrotoxicity in patients with peritoneal carcinomatosis undergoing cytoreduction and hyperthermic intraperitoneal intraoperative chemotherapy (HIPEC-cisplatin). Prophylaxis was with imipenem/cilastatin. Cilastatin is a selective inhibitor of renal dehydropeptidase I in the proximal renal tubule cells that can reduce the nephrotoxicity of cisplatin. Unfortunately, cilastatin is not currently marketed alone, and can only be administered in combination with imipenem. The study has a retrospective part that serves as a control (n = 99 patients receiving standard surgical prophylaxis) and a prospective part with imipenem/cilastatin prophylaxis corresponding to the study group (n = 85 patients). In both groups, we collected specific data on preoperative risk factors of renal damage, fluid management, hemodynamic control, and urine volume during surgery (including the hyperthermic chemotherapy perfusion), as well as data on hemodynamic and renal function during the first seven days after surgery. The main finding of the study is that cilastatin may exert a nephroprotective effect in patients with peritoneal carcinomatosis undergoing cytoreduction and hyperthermic intraperitoneal cisplatin perfusion. Creatinine values remained lower than in the control group (ANOVA test, p = 0.037). This translates into easier management of these patients in the postoperative period, with significantly shorter intensive care unit (ICU) and hospital stay.

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We wanted to see if cranial anatomical alterations could influence the vascularization of the eyeball, particularly in the production of ophthalmic varicose veins. Orbital dissection of 85 years old woman (who suffered from Alzheimer's disease and respiratory failure).We observed, when performing a horizontal section of the skull to access the roof of the orbit, that the intracranial surface of the anterior and middle cranial fossae was partially covered by bony outgrowths, with the optical aperture and superior orbital fissure included. Also, when removing the roof of the orbits and beginning to extract the orbital fat we saw a dark, bilateral mass in the upper part of the orbital cavity corresponding to very dilated vessels. Bone alteration of the internal face of the skull was a diffuse intracranial hyperostosis and the dark dilated masses were superior ophthalmic varicose veins.Our hypothesis is that the origin of these ophthalmic varicose veins was the narrowing of the superior orbital fissure due to excessive bone proliferation. Intracranial hyperostosis produces a difficulty in draining orbital venous blood and, consequently, venous dilation. For this reason, we should consider this in the differential diagnosis

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Most survival outcomes in out-of-hospital cardiac arrest (OHCA) are provided by emergency medical services (EMS) without a doctor on board. Our objective was to determine such outcomes in a whole country with public physician-led EMS. METHODS: We analyzed data from a nationwide prospective registry of OHCA cases attended by 19 public EMS in Spain, covering the period from 1-October 2013 to 30-October 2014. RESULTS: Advanced life support (ALS) was initiated in 9347 cases (incidence 18.6 cases/105 inhabitants per year). Resuscitation was considered futile in 558 cases (5.9%), and ALS was continued in 8789 cases (94.1%); mean age 63.5±17 years, 72.1% men. Initial rhythm was shockable in 22.1% of cases. Basic life support (BLS) was provided by bystanders in 1602 (24%) cases (635 of them with telephone assistance from the dispatch center). Of 8789 patients receiving ALS, 72.1% men, 2669 (30.4%) patients had return of spontaneous circulation on hospital arrival, 50.6% when the initial rhythm was shockable. Hospital discharge with good neurological status (CPC1-2) was found in 11.1% of the study population and in 27.6% when considering the Utstein comparator group of patients. A total of 216 (2.5%) patients arrived at the hospital with ongoing resuscitation, of whom only one survived with CPC1-2, and 165 (1.9%) patients were included in non-heart-beating donation programs. CONCLUSIONS: In Spain with physician-led EMS, OHCA survival with CPC1-2 reached a reasonable percentage despite only a modest contribution of bystander BLS. Ongoing resuscitation strategy seems to be futile except when considering non-heart beating donation programs.

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BACKGROUND: The use of prophylactic mesh to prevent incisional hernia is becoming increasingly common in midline laparotomies and colostomies. The incidence of incisional hernia after subcostal laparotomies is lower than after midline incisions. Nevertheless, the treatment of subcostal incisional hernia is considered to be more complex. Currently, there are no published data about mesh augmentation procedures to close these laparotomies. METHODS: This was a longitudinal, prospective, cohort study of patients undergoing a bilateral subcostal laparotomy in elective operations. The mesh group was a group of patients operated consecutively between 2011 and 2013 with a prophylactic self-fixation mesh. The control group was selected from a retrospective analysis of patients operated between 2009 and 2010 and closed with a conventional protocol of 2-layer closure. The incidence of incisional hernia was recorded both clinically and radiologically for 2 years. RESULTS: A total of 57 patients were included in the control group and 58 in the mesh group. Most patients underwent gastric, hepatic, and pancreatic operations. Both groups were homogeneous in terms of their clinical and demographic characteristics. Operative time and hospital stay were similar in both groups. Both groups had a comparable rate of local and systemic complications. Ten patients (17.5%) in the control group developed an incisional hernia, and only 1 patient (1.7%) in the mesh group developed an incisional hernia (P = .0006). CONCLUSION: The incidence of incisional hernia after a conventional closure of bilateral subcostal laparotomy is significant. The use of a mesh augmentation procedure for closing bilateral subcostal laparotomies is safe and may reduce the incidence of incisional hernia.

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Objetivo. Demostrar la relación entre la afectación endometriósica del apéndice cecal y el desarrollo de una apendicitis aguda. Pacientes y métodos. Presentamos una serie institucional de 8 pacientes con endometriosis apendicular diagnosticadas tras apendicectomía entre junio de 2009 y marzo de 2014. Resultados. La media de edad fue 40,6 años, 6 en edad fértil. En 5 (62,5%) la afectación endometriósica apendicular resultó única y en 3 (37,5%) múltiple, fundamentalmente en el ovario. Siete (87,5%) iniciaron los síntomas como una apendicitis aguda. Los implantes endometriósicos afectaban la capa serosa en 6 pacientes, la capa muscular en una y la grasa periapendicular en otra. Conclusión. El diagnóstico de endometriosis apendicular en mujeres con apendicitis aguda solo se puede realizar tras el examen de las piezas de apendicectomía, aunque puede ser sospechado en el contexto clínico. La laparoscopia permite un diagnóstico adecuado con exploración completa de la pelvis, la apendicectomía y el tratamiento de otras lesiones (AU)

Aim. To determine the relationship between endometriotic involvement of the appendix and the development of acute appendicitis. Patients and methods. We report a series of 8 patients with appendiceal endometriosis diagnosed after appendicectomy from June 2009 to March 2014. Results. The mean age was 40.6 years. Six patients were of reproductive age. Endometriotic appendiceal involvement alone was found in 5 patients (62.5%) and multiorgan involvement, mainly affecting the ovary, in 3 patients (37.5%). Clinical presentation was acute appendicitis in 7 patients (87.5%). Endometriotic implants involved the serous layer in 6 patients, the muscle layer in one patient, and periappendiceal fat in another patient. Conclusion. Diagnosis of appendiceal endometriosis in women with acute appendicitis can only be performed after specimen study, although it may be suspected in the clinical context. Laparoscopy allows pelvic and abdominal cavity examination, appendectomy, and the treatment of other lesions (AU)

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ObjetivosConocer el grado de inercia terapéutica (IT) y determinar los factores asociados al paciente, médico y organización sanitaria en pacientes hipertensos asistidos en atención primaria (AP).DiseñoEstudio transversal y multicéntrico.EmplazamentoMuestra de Equipos de AP de toda España.ParticipantesEl estudio fue realizado entre médicos de AP mediante un cuestionario y registro clínico de 4 pacientes.Mediciones principalesSe calculó la IT para cada paciente (ITp) como la proporción de visitas en las que no se produce un cambio en la medicación cuando está indicado.ResultadosUn total de 543 médicos aportaron datos de 2.032 pacientes, que cumplían el requisito de indicación de cambio, en el 77,8% de los casos se actuó con IT. La ITp observada fue inexistente o baja para el 17,1% de los pacientes, intermedia para el 42% y alta para el 40,8%. Los factores, relativos a los pacientes, que más se asociaron con la ITp alta fueron la edad (p<0,001), diabetes (p<0,001), ictus (p<0,01), obesidad (p<0,01) y el nivel bajo de estudios (p<0,001). Ser mujer, tener menos de 45 años o más de 55, ser médico de familia con un programa de formación diferente al MIR y trabajar en el sector público aumentaron la probabilidad de ITp (p<0,001 para todos los supuestos).ConclusionesLos resultados del estudio indican que en 7 de cada 10 visitas realizadas por pacientes hipertensos en AP se produce IT. Existen diferencias importantes en función de las características clínicas de los pacientes, de los médicos y de las consultas(AU)

ObjectivesTo determine the level of therapeutic inertia (TI), and the factors associated to the patient, doctor and the health organisation, in hypertensive patients treated in Primary Care (PC).DesignCross-sectional, multicentre study.SettingA sample of PC Teams from all over Spain.ParticipantsThe study was conducted among PC doctors using a questionnaire and clinical records of 4 patients.Main measurementsThe TI was calculated for each patient (TIp) as the proportion of visits in which there was no change in medication when this was indicated.ResultsA total of 543 PC doctors provided data on 2,032 patients, who fulfilled the indication of a change in requirement. There was TI In 77.8% of cases. The TIp observed was non-existent or low for 17.1% of the patients, intermediate for 42% and high for 40.8%. For the patients, the factors most associated with TIp were, age (P<.001), diabetes (P<.001), stroke (P<.01), obesity (P<.01) and a low education level (P<.001). To be female, be less than 40years or more than 55years, to be a family doctor with a training program other than MIR and to work in the public sector increased the probability of TIp (P<.001 for all the assumptions).ConclusionsThe results of the study indicate that there is TI in 7 out every 10 visits made by hypertensive patients in Primary care. There are significant differences as regards the clinical characteristics of the patients and of the doctors(AU)

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OBJECTIVES: To determine the level of therapeutic inertia (TI), and the factors associated to the patient, doctor and the health organisation, in hypertensive patients treated in Primary Care (PC). DESIGN: Cross-sectional, multicentre study. SETTING: A sample of PC Teams from all over Spain. PARTICIPANTS: The study was conducted among PC doctors using a questionnaire and clinical records of 4 patients. MAIN MEASUREMENTS: The TI was calculated for each patient (TIp) as the proportion of visits in which there was no change in medication when this was indicated. RESULTS: A total of 543 PC doctors provided data on 2,032 patients, who fulfilled the indication of a change in requirement. There was TI In 77.8% of cases. The TIp observed was non-existent or low for 17.1% of the patients, intermediate for 42% and high for 40.8%. For the patients, the factors most associated with TIp were, age (P<.001), diabetes (P<.001), stroke (P<.01), obesity (P<.01) and a low education level (P<.001). To be female, be less than 40 years or more than 55 years, to be a family doctor with a training program other than MIR and to work in the public sector increased the probability of TIp (P<.001 for all the assumptions). CONCLUSIONS: The results of the study indicate that there is TI in 7 out every 10 visits made by hypertensive patients in Primary care. There are significant differences as regards the clinical characteristics of the patients and of the doctors.

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We examined the influence of the reproductive cycle and environmental variables on the gonadal fatty acid profile in the tropical scallop Nodipecten nodosus. Individuals from a natural population in north-eastern Venezuela (Caribbean Sea) were sampled monthly during one year. The gonadosomatic index (GSI) and a visual assessment of gonadic status are also reported. The environmental conditions characterized by chlorophyll a, temperature and seston concentration were measured in parallel. The highest reproductive activity, with a GSI of 13-18%, was observed from November 2003 to April 2004, and a decrease in GSI, taken as an indication of three spawning periods, was recorded in October, January and May-June. The GSI was 5-8% outside these intervals. A similar trend was observed in maturity stage frequency. Statistical analysis (MDS-ANOSIM) established two different periods; one dominated by upwelling (January to July) and the other characteristic of non-upwelling conditions (August to December). The fatty acids 16:0, 22:6n-3, 20:5n-3 and 16:1n-7 were responsible for the differences between two periods and explained 50% of the observed variance. Accordingly, during the upwelling period, fatty acids such as 22:6n-3 were positively correlated with temperature, organic seston and bivalves in the spent sexual stage and inversely related to the GSI. Furthermore, individuals in the ripe sexual stage were positively related to 20:5n-3 and 18:3n-3, whereas chlorophyll a was directly related to 18:1n-7 and 16:1n-7. In the non-upwelling period, a significant and positive correlation was obtained between fatty acids such as 20:5n-3 and 22:6n-3 and the GSI and the bivalves in the ripe sexual stage, whereas these acids were inversely correlated with the spent sexual stage. In addition, chlorophyll a was positively related to 18:1n-9 and 18:2n-6. Changes in the gonadal fatty acid profile of N. nodosus were influenced by the environmental variables (exogenous factors) during the upwelling and non-upwelling periods and by reproductions (endogenous factors).

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Como medio de mejora de la baja productividad investigadora de calidad en medicina de urgencias, se puede recurrir a la cooperación y al conocimiento de los sistemas de evaluación de los organismos financiadores. Con dicho propósito se presenta una descripción de los dos principales sistemas de evaluación empleados por los organismos financiado esa nivel nacional (FIS) y a nivel europeo (Programas de Cooperación en Salud del Séptimo Programa Marco). Las dimensiones seleccionadas para el análisis fueron: la metodología, el proceso y los criterios de evaluación, el peso del criterio y las características de los evaluadores. Existen diferencias tanto a nivel organizativo, objetivos, política, asignación de recursos, mecanismo de financiación, importancia otorgada a la actividad investigadora, organización de los procesos de investigación y gestión de la investigación, que dificultan la comparación en materia de investigación. Las limitaciones detectadas afectan, entre otras, a la falta de retorno a los evaluadores, la ausencia de confidencialidad sobre los equipos y al déficit de mecanismos de homogeneización de criterios entre evaluadores a lo largo del tiempo (AU)

The knowledge available in the evaluation systems that funding agencies set up to review applications can be taken advantage of to increase the amount of well-designed research in emergency medicine, improving the current situation of low productivity. To further that end, we describe the 2 main review systems used by the Spanish national funding agency and the European Seventh Framework Programme for health research. The dimensions analyzed were as follows: procedures, processes and evaluation criteria; criterion weighting; and characteristics of reviewers. The 2 systems differ in terms of general organization, objectives, policies, allocation of resources, funding mechanisms, importance placed on research productivity, organization of research processes and management. Comparison is therefore difficult. Limitations detected include the lack of feedback for reviewers, of blinding, and of mechanisms to guarantee that evaluation criteria are applied consistently by reviewers over time (AU)

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The diversity of a sublittoral epifaunal mollusk community of Punta Patilla, Sucre State, Venezuela, was studied from September 1990 to September 1991. We identified 25 species (14 bivalves and 11 gastropods) of mollusks that inhabit gravel, soft sand and bottoms covered by Thalassia testudinum.Total diversity indices were H´= 3.42, J´= 0.74 and 1-D = 0.85. Monthly diversity reached its maximum in March 1991 (3.12 bits/ ind.), June 1991 (2.88 bits/ind.) and September 1991 (2.95 bits/ind.); minimum diversity was recorded in August 1991 (1.20 bits/ind.).A log series model showed a diversity index alpha = 4.56 for species abundance data and alpha = 3.11 for biomass data. The more abundant species were Chione cancellata, Antigona listeri, Chione granulata and Arca zebra among the bivalves, and Chicoreus brevifrons, Turritella variegata and Phyllonotus pomum among the gastropods (which present maximum biomass). The average total biomass (56.80 g/m2 )is low when compared to reports from other tropical zones

Se estudió la diversidad de una comunidad malacológica sublitoral en Punta Patilla, Estado Sucre, Venezuela, desde septiembre 1990 hasta septiembre 1991. Se identificaron 25 especies, 14 bivalvos y 11 gasterópodos. Los parámetros de diversidad total en número de la comunidad fueron H´=3.41 bits/ind., J´=0.74 y 1-D =0.85. Las máximas diversidades mensuales se observaron en marzo 1991 (3.12 bits/ind.), junio 1991 (2.88 bits/ind) y septiembre 1991 (2.95 bits/ind.) y la mínima ocurrió en agosto 1991 (1.20 bits/ind.). Los datos del número de individuos conforman una línea recta ajustada por la serie logarítmica con un índice alfa =4.56 y alfa =3.11 para los de biomasa. Las especies más abundantes fueron Chione cancellata, Antigona listeri, Chione granulata y Arca zebra entre los bivalvos, y Chicoreus brevifrons, Turritella variegata y Phyllonotus pomum entre los gasterópodos, estos presentaron las máximas biomasas individuales. La biomasa total promedio de la comunidad (56.80 g/m2 ) es baja cuando se compara con otros reportes de áreas tropicales. Los moluscos habitaron fondos de grava y arenofangoso cubiertos por praderas de Thalasia testudinum

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BACKGROUND: The use of hair dyes has been inconsistently associated with an increased risk of lymphomas. We explore hair dye use and lymphoma risk in a case-control study in Spain. METHODS: We studied 574 incident lymphoma cases and 616 hospital controls in a multicentric study in Spain. Information on hair dye use was obtained through a personal interview together with information on other known or putative risk factors for lymphoma. Unconditional logistic regression analysis was used to estimate odds ratio (OR) and 95% confidence intervals (95% CI). All ORs were adjusted for pathology center, sex, age, and house ownership. RESULTS: Ever use of hair dyes was associated with a non-significant 20% increased risk of lymphoma (OR = 1.2, 95% CI 0.9-1.7) with a slightly higher risk observed for those using permanent hair dyes (OR = 1.3, 95% CI 0.9-1.9). No association was observed with duration of use or lifetime doses of hair dyes. Among all lymphomas categories, only chronic lymphocytic leukaemia (CLL) was significantly associated with the use of hair dyes (OR = 2.3, 95% CI 1.1-4.7). The risk of CLL increased with lifetime doses received. CONCLUSIONS: Ever use of hair dye products is unlikely to substantially modify the risk of lymphoma. The observed association with CLL needs to be replicated.

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The diversity of a sublittoral epifaunal mollusk community of Punta Patilla, Sucre State, Venezuela, was studied from September 1990 to September 1991. We identified 25 species (14 bivalves and 11 gastropods) of mollusks that inhabit gravel, soft sand and bottoms covered by Thalassia testudinum. Total diversity indices were H' = 3.42. J' = 0.74 and 1-D = 0.85. Monthly diversity reached its maximum in March 1991 (3.12 bits/ ind.), June 1991 (2.88 bits/ind.) and September 1991 (2.95 bits/ind.); minimum diversity was recorded in August 1991 (1.20 bits/ind.). A log series model showed a diversity index alpha = 4.56 for species abundance data and alpha = 3.11 for biomass data. The more abundant species were Chione cancellata, Anigona listeri, Chione granulata and Area zebra among the bivalves, and Chicoreus brevifrons, Turritella variegata and Phllonotus pomum among the gastropods (which present maximum biomass). The average total biomass (56.80 g/m2) is low when compared to reports from other tropical zones.

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El chipi-chipi Donax denticulatus es una especie dominante en las comunidades de playas de arena de las costas del Caribe venezolano. El crecimiento y la distribución de tallas de una población intermareal fue analizada mensulmente entre octubre 2000 y junio 2001 en Playa Brava, Chacopata, Venezuela. Los muestreos se realizaron en transectos perpendinculares a la línea de costa. La distribución de tallas fue estable, constituida fundamentalmente por bivalvos adultos con escaso reclutamiento (20-26 mm). La densidad media fue de 33,13 ± 6,35 ind.m-² sin cambios significativos en el tiempo. La relación longitud peso fue altamente significativa (R²>0,60). Los parámetros de crecimiento según la función von Bertalanffy fueron L infinito= 31,47 mm, K= 1,48 año-¹ sugiriendo que la población de Playa Brava posee una tasa de crecimiento alta y una longevidad de 18 meses. La tasa instantánea de mortalidad (Z) analizada para individuos grandes (> 22 mm) fue también alta (2,93 año-¹). Debido a la inexistencia de explotación del banco, la mortalidad estimada es asumida como la natural

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Se analizó la condición fisiológica mensual del mejilló marrón Perna perna (Bivalvia: Mytilidae) del Morro de Guarapo, Estado Sucre, Venezuela, según las relaciones alométricas, índice de condición (IC), gonádico (IG) y de rendimiento (R) de hembras y machos, en diferentes estados de maduración sexual durante 12 meses. Las mayores correlaciones fueron presentadas por la longitud total con los demás parámetros biométricos, y por la masa de la concha con el ancho de la concha. la masa seca de los tejidos blandos (gónada, músculo y resto de tejido somático) en ambos sexos presentó los valores mínimos en mayo y diciembre, asociados con la disminución de IG, sugiriendo períodos de mayor actividad de desove. Los valores mínimos del IG y R se observaron en mayo y del IC en febrero, con máximos del IG en marzo, del IC en octubre y de R en febrero, con promedios anuales de 15,36 ñ 6,92 por ciento (IG), 18,69 por ciento ñ 6,39 por ciento (IC) y 29,37 ñ 6,09 por ciento (R). Se detectaron diferencias significativas del IG, IC, R y de la masa seca de las gónadas entre meses y estados de maduración sexual, del IG entre sexos y del IG, R y masa de las gónadas según la talla. Ambos sexos presentaron el mismo patrón de variación anual en la condición fisiológica asociado al ciclo reproductivo, registrándose los valores mayores para las hembras. P.perna muestra una condición fisiológica dependiente de factores endógenos como la reproducción continua en interacción con factores ambientales de la zona, principalmente la disponibilidad de alimento generado por los períodos de surgencia y estratificación en la región. La especie muestra una buena condición fisiológica y alto contenido de tejidos blandos, siendo la explotación del recurso conveniente con individuos en el estadío maduro y una longitud comprendida entre 60-80mm

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La diversidad malacológica de una comunidad submareal de Arca zebra se estudió, desde septiembre, 1990 hasta septiembre, 1991, en Chacopata, Estado Sucre, Venezuela. Se identificaron 40 especies (24 de bivalvos y 16 de gasterópodos). Los parámetros de diversidad en número de la comunidad fueron bajos (H` = 2.087 bits /ind., J` = 0.392, Simpson = 0.528) cuando se comparan con otros reportes de áreas tropicales. Los datos del número de individuos por especies con el rango conforman una línea recta ajustada por la serie logaritmica, con un índice de diversidad (a) de 5.66. Las máximas diversidades mensuales se observaron en septiembre, 1990 (1.63 bits/ind.) y julio, 1991 (1.60 bits/ind.), la mínima ocurrió en junio, 1991 (0.52 bits/ind.). De las 40 especies identificadas, la pepitona, Arca zebra fue la especie dominante en número (68.87 %) y en biomasa (72.34 %), seguida por Pinctada imbricata, Modiolus squamosus, Chama macerophyla y Anadara notabilis. Los gasterópodos predadores Phyllonotus pomum, Chicoreus brevifrons y Murex recurvirostris parecen tener relaciones tróficas con la especie dominante. La biomasa promedio total en peso húmedo con la concha (469.20 + 263 g m-2) es alta e indica que A. zebra, la especie dominante de rápido crecimiento, desempeña el papel más importante en la comunidad como un eficiente filtrador, que convierte el alimento planctónico en biomasa disponible, soportando una de las pesquerías más importantes de la región.

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