RESUMO
A custom-built controlled-rate freezing machine is described. It operates by automatically raising and lowering the sample carrier in a static column of liquid nitrogen vapour. It is controlled by a computer-assisted thermocouple feedback system that operates a stepper motor driving the sample carrier. The cooling protocol is divided into three phases: cooling from +5 to -5 C, initiation of ice nucleation, and cooling from -5 to -80 C. Experiments are described to validate the device over a range of different cooling rates. A freezing protocol is established to cool samples in plastic straws over a range of rates up to 80 C/min, with rapid and consistent absorption of the latent heat.
Assuntos
Criopreservação/instrumentação , Animais , Desenho de Equipamento , Congelamento , Masculino , Preservação do Sêmen/instrumentação , SuínosRESUMO
PIP: Jet injection was 1st introduced into Brazil's smallpox eradication program in 1965 following field studies in Amapa Territory that confirmed the effectiveness of this technique. Between January 27-February 15, 1965, vaccination teams vaccinated 53,654 people in this territory, representing 89% of the target population. Local personnel with limited training were able to operate the jet injectors with few problems. Vaccination take rates were significantly higher both in primary vaccinees and revaccinees when the jet injectors as opposed to the conventional multiple pressure technique was used. Take rates ranged from 81-90% in the various villages, and there were only 2 complications reported. An average of over 600 vaccinations could be performed per hour with jet injection and total man-hours expended were 1/3 the number involved in the traditional technique. The cost per vaccination was estimated to be US$0.022 for the jet injector technique compared with 0.067 for the multiple pressure approach. Overall, the experience in Amapa Territory indicates that jet injection has obvious advantages, including a reduction in manpower needs, a reduction in transportation needs, increased efficiency, and a reduction in vaccine needs. For best use of the equipment, priority should be given to urban areas.^ieng
Assuntos
Injeções/instrumentação , Vacina Antivariólica , Varíola/prevenção & controle , Vacinação/instrumentação , Brasil , Custos e Análise de Custo , Mão de Obra em Saúde , Humanos , Injeções Intradérmicas , População Rural , População UrbanaRESUMO
Primary vaccination by intradermal jet injection, using diluted smallpox vaccine, was compared with multiple-pressure vaccination in 625 Jamaican children. The cutaneous and antibody response patterns were evaluated. The primary take rates among those jet vaccinated were 97% or more in those receiving vaccines with a titre of 10(6.3) TCID(50)/ml and 10(7.0)TCID(50)/ml, and 96% in those vaccinated by multiple pressure, using undiluted vaccine. The primary take rates in subjects receiving jet-injected vaccine with titres of 10(6.0) TCID(50)/ml and 10(5.0) TCID(50)/ml were 90% and 62%, respectively. Among subjects tested who developed Jennerian vesicles, all but 3 demonstrated seroconversion. In those who failed to develop primary Jennerian vesicles, there was also a failure of neutralizing-antibody development. Vesicle and scar sizes were generally smaller in the jet-vaccinated subjects than in those vaccinated by the multiple-pressure technique. Infants tolerated jet vaccination without difficulty. Vaccinial complications did not occur in any subject. The intradermal jet injection of 0.1 ml of vaccine with a titre 10(6.3) TCID(50)/ml or higher is recommended as a highly effective method for achieving successful primary smallpox vaccination. The method appears best suited for use in mass smallpox-vaccination programmes.