Biological safety cabinetry

The biological safety cabinet is the one piece of laboratory and pharmacy equipment that provides protection for personnel, the product, and the environment. Through the history of laboratory-acquired infections from the earliest published case to the emergence of hepatitis B and AIDS, the need for health care worker protection is described. A brief description with design, construction, function, and production capabilities is provided for class I and class III safety cabinets. The development of the high-efficiency particulate air filter provided the impetus for clean room technology, from which evolved the class II laminar flow biological safety cabinet. The clean room concept was advanced when the horizontal airflow clean bench was manufactured; it became popular in pharmacies for preparing intravenous solutions because the product was protected. However, as with infectious microorganisms and laboratory workers, individual sensitization to antibiotics and the advent of hazardous antineoplastic agents changed the thinking of pharmacists and nurses, and they began to use the class II safety cabinet to prevent adverse personnel reactions to the drugs. How the class II safety cabinet became the mainstay in laboratories and pharmacies is described, and insight is provided into the formulation of National Sanitation Foundation standard number 49 and its revisions. The working operations of a class II cabinet are described, as are the variations of the four types with regard to design, function, air velocity profiles, and the use of toxins. The main certification procedures are explained, with examples of improper or incorrect certifications. The required levels of containment for microorganisms are given. Instructions for decontaminating the class II biological safety cabinet of infectious agents are provided; unfortunately, there is no method for decontaminating the cabinet of antineoplastic agents.

Screening for prolonged incubation of HTLV-I infection in British and Jamaican relatives of British patients with tropical spastic paraparesis

OBJECTIVE

To compare the prevalence of antibody to and proviral DNA of the retrovirus HTLV-I in relatives of 11 British patients with tropical spastic paraparesis who had migrated from Jamaica before they developed symptoms, and to examine factors possibly related to transmission of HTLV-I.

DESIGN

Migrant, family study. Antibody state was determined by several methods and confirmed by western blotting; the polymerase chain reaction was used to detect proviral DNA.

SETTING

Britain and Jamaica.

SUBJECTS

All available first degree relatives: those born and still resident in Jamaica (group 1); those born in Jamaica who migrated to Britain (group 2); and index patients' children who were born and resident in Britain (group 3). All had been breast fed and none had had blood transfusions.

RESULTS

Of the 66 living relatives, 60 were traced. Seroprevalence among those born in Jamaica (irrespective of current residence) was 22% (10/46; 95% confidence limits 9 to 34%) compared with zero among British born offspring (0/14) and was higher in group 2 at 33% (7/21; 12 to 55%) than in group 1 at 12% (3/25; 0 to 25%). (Patients in group 1 had the greatest mean age.) Proviral DNA was not detected in any subject negative for HTLV-I antibody, making prolonged viral incubation in those negative for the antibody unlikely.

CONCLUSION

In this sample factors related to place of birth and early residence were more important in transmission of HTLV-I than maternal or age effects. In areas with a low to moderate prevalence policies of preventing mothers who are carriers of the virus from breast feeding would be premature.

Effect of vitamin E on vitamin C-induced lymphocytopenia

Large daily doses of vitamin C resulted in lymphocytopenia in stressed mice caused by excessive plasma levels of adrenal corticosteroids. Vitamin C plus E resulted in less severe lymphocytopenia because vitamin E has a lymphoproliferative effect.

Aggressive behavior and lymphocyte damage

Aggressive and passive mice were placed together in one cage. Lymphocyte counts were taken for both groups over a 10-day period. Although lymphocyte damage occurred, there was no significant difference in the severity of lymphocyte damage between the two groups.

Effect of ascorbic acid on pituitary weight during stress

40 Sprague-Dawley rats were subjected to stress by crowding and water immersion for five days. Three groups of animals were compared: controls ( n = 20), stressed animals dosed with ascorbic acid ( n = 20), and stressed animals not dosed with ascorbic acid ( n = 20). Ascorbic acid prevented both adrenal and pituitary hypertrophy in stressed animals. Ascorbic acid appears to act as a potentiating factor for ACTH when there is an increased demand for ACTH during stress.

Dietary supplementation with vitamin C delays the onset of fatigue in isolated striated muscle of rats

The purpose of this study was to assay the effect of prolonged vitamin C supplementation on contraction time and strength in the gastrocnemius muscle of the rat. Fifteen male Sprague-Dawley rats were given 30 mg of vitamin C orally per day for thirty days, while an additional fifteen animals served as controls. Contraction of the isolated gastrocnemius muscle was induced by electrical stimulation, and strength and time to fatigue was measured. Results indicate that the supplementation of vitamin C prolongs contraction time by 19% thus delaying fatigue but had no affect on muscle strength.

Acquired megacolon associated with acute lead poisoning

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Comparison of accuracy in five measures of stress

36 Sprague-Dawley rats were subjected to stress by immersion, erratic photoperiod and crowding for 28 days. Control and experimental animals were sacrificed and the thymus, spleen, adrenals, testis, and pituitary were removed and their weights were recorded as a ratio of organ weight to body weight. The pituitary was the most accurate measure of stress according to Z scores.