RESUMEN
The photoperiod is the controller of reproductive cycles in temperate climates for most mammalian species. Several nonphotoperiodic cues appear to control reproductive status at lower latitudes. We tested the roles of the photoperiod or water availability on the reproductive status of the desert-dwelling Shaw's jird (Meriones shawi) trapped from a moderately temperate climate (approximately 30 degrees N in Egypt). Males and females were transported to the laboratory and, in Experiment 1, were housed in either the longest (LDs) or shortest (SDs) photoperiod that occurs naturally at this latitude (14 h light, 10 h dark, and 10 h light, 14 h dark, respectively). In Experiment 2, LD-housed male jirds were subjected to a water availability schedule that inhibits reproductive status in a closely related species (Meriones unguiculatus). Specifically, one group had no free water, but had lettuce available once a week for 24 h (control jirds received free water for 10-60 min/day). Neither photoperiod nor free-water deprivation affected reproductive status of male or female jirds. That is, neither testes mass nor spermatogenetic activity (males), nor uterine mass nor folliculogenesis (females) were affected by either condition. In addition, photoperiod did not affect body or white adipose tissue (WAT) masses, although SDs decreased carcass lipid in males. Free-water deprivation decreased body and WAT pad masses, and all carcass components. Collectively, these results suggest that changes in day length or water availability alone do not affect reproductive status in Shaw's jird.
Asunto(s)
Clima Desértico , Metabolismo Energético/fisiología , Gerbillinae/fisiología , Conducta Sexual Animal/fisiología , Medio Social , Equilibrio Hidroelectrolítico/fisiología , Adaptación Fisiológica/fisiología , Tejido Adiposo/fisiología , Animales , Composición Corporal/fisiología , Peso Corporal/fisiología , Ritmo Circadiano/fisiología , Femenino , Masculino , Psicofisiología , Privación de Agua/fisiologíaRESUMEN
Many animal species living in temperate zones show annual body fat cycles. In an apparent regulation of total body fat, species showing naturally occurring decreases in adiposity in the fall (e.g., meadow voles and Siberian hamsters) are resistant to high-fat diet (HFD)-induced obesity in short, "winter-like" days (SDs), and in long, "summer-like" days (LDs) at their peak adiposity. SD-exposed Shaw's jirds (Meriones shawi) show SD-induced decreases in body fat; therefore, we predicted they also would be resistant to HFD-induced obesity. Male jirds were fed a standard chow diet or a HFD, and half of each group was exposed to LDs or SDs. SD-exposed jirds significantly decreased their carcass lipid content and testes mass compared with LD controls, but not body or WAT pad masses. HFD feeding in either photoperiod did not affect any of these measures, nor did it trigger overeating. Thus, it appears disadvantageous for this, and other species, that exhibit body fat peaks in the LDs of summer and nadirs in the SDs of winter, to fatten further or dampen their body fat losses, respectively, whereas species that exhibit body fat nadirs in the LDs of summer and peaks in the SDs of winter do become fat in LDs, and even fatter in SDs, when fed a HFD (e.g., Syrian hamsters). This dichotomous separation of HFD-induced body fat responses to HFD feeding among species showing opposite seasonal lipid mass peaks and nadirs may prove useful in understanding resistance or susceptibility to HFD-induced obesity, especially because they are naturally occurring.
Asunto(s)
Tejido Adiposo/metabolismo , Composición Corporal/fisiología , Grasas de la Dieta/administración & dosificación , Gerbillinae/fisiología , Fotoperiodo , Animales , Ingestión de Alimentos/fisiología , MasculinoRESUMEN
The purpose of this study was to examine the effect of the photoperiod on reproductive status and body and lipid masses in four Egyptian desert rodent species (Dipodillus dasyurus, Acomys cahirinus, Gerbillus andersoni, and Gerbillus pyramidum). Adult males and females were housed in long days for 11 wk. At that time, one-half of the animals were killed and the remaining animals were moved to short days (SDs) for 11 wk. Some individuals of Gerbillus andersoni and Gerbillus pyramidum had access to running wheels. Testes index and spermatogenesis, but not testis mass, were decreased in all species in SDs. In contrast, SDs did not affect female reproductive status in all species. Exercise stimulated spermatogenesis but did not affect female reproductive status. SDs increased body and lipid masses in male Acomys cahirinus, but not in other species. Collectively, these desert rodent species were responsive to day length changes, but these changes alone did not induce robust alterations in reproductive status and body and lipid masses.
Asunto(s)
Animales Salvajes/fisiología , Clima Desértico , Fotoperiodo , Roedores/fisiología , Tejido Adiposo/anatomía & histología , Animales , Composición Corporal , Peso Corporal/fisiología , Femenino , Gerbillinae , Masculino , Ratones , Reproducción/fisiología , Caracteres SexualesRESUMEN
An analysis of the chest recurrences was conducted in 72 consecutive patients with limited small cell lung cancer treated in two successive phase II trials alternating six induction chemotherapy courses and three series of thoracic radiotherapy, followed by maintenance chemotherapy. The total radiation dose was 45 Gy (3 series of 15 Gy) in the first trial, and 55 (20, 20 and 15 Gy) in the second. The effect of the irradiated volume was investigated by comparing the local relapse rates in the group of patients treated by radiation fields encompassing the initial tumor volume to another group in which the initial target volume was not fully covered by radiation fields. The definition of these two groups was performed retrospectively by examination of radiological, fiberoptic bronchoscopy initial findings, technical radiation charts and check films. The local recurrence rate were 33 and 36% in each group (no significant difference). This finding could suggest that tumor shrinkage after chemotherapy might allow the use of "reduced" radiation volumes. However, the limited number of patients does not permit a definite conclusion. The effect of radiation dose was investigated by comparing the local control rates in the two consecutive trials which delivered 45 and 55 Gy, respectively. No difference in long-term local control was found: the addition of 10 Gy in the second trial only seemed to delay the appearance of local recurrences by 6 months. Twenty percent of patients died from a local relapse without evidence of distant metastases.(ABSTRACT TRUNCATED AT 250 WORDS)
Asunto(s)
Carcinoma de Células Pequeñas/radioterapia , Neoplasias Pulmonares/tratamiento farmacológico , Neoplasias Pulmonares/radioterapia , Recurrencia Local de Neoplasia , Análisis Actuarial , Antineoplásicos/uso terapéutico , Carcinoma de Células Pequeñas/tratamiento farmacológico , Carcinoma de Células Pequeñas/mortalidad , Protocolos Clínicos , Terapia Combinada , Evaluación de Medicamentos , Femenino , Estudios de Seguimiento , Humanos , Neoplasias Pulmonares/mortalidad , Masculino , Persona de Mediana Edad , Análisis Multivariante , Dosificación RadioterapéuticaRESUMEN
Sixty-three evaluable patients with limited small cell lung carcinoma were entered into two pilot studies alternating 6 cycles of combination chemotherapy (Doxorubicin 40 mg/m2 d 1; VP16213 75 mg/m2 d 1, 2, 3; Cyclophosphamide 300 mg/m2 d 3, 4, 5, 6; and Methotrexate 400 mg/m2 d 2--plus folinic acid rescue--or Cis-Platinum 100 mg/m2 d 2) with 3 courses of mediastinal radiotherapy as induction treatment. The first course of radiotherapy started 10 days after the second cycle of chemotherapy; there was a 7 day rest between chemotherapy and radiotherapy courses. This 6 month induction treatment was followed by a maintenance chemotherapy. The total mediastinal radiation dose was increased from 4500 rad in the first study to 5500 rad in the second. Both protocols obtained a complete response (CR) rate of greater than 85% (with fiberoptic bronchoscopy and histological verification). Local control at 2 years was 61% in the first study and 82% in the second. Relapse-free survival at 2 years was 32 and 37%, respectively. Toxicity was acceptable. We conclude that our results justify further clinical research in alternating radiotherapy and chemotherapy schedules.