Composition of the tectal and posterior commissures of the chick (Gallus domesticus)

In chick, the tectal and posterior commissures form a continuous band of axons lying in the dorsal aspect of the meso-diencephalon. In midline sagittal sections, two zones can be clearly defined. The rostral zone (RZ) contains about 290,000 axons of which 32% are myelinated. The caudal zone (CZ) contains about 911,000 fibers of which 12% are myelinated. The majority of unmyelinated fibers in RZ and CZ are between 0.15 and 0.40 micrometers in diameter. The majority of myelinated fibers in both RZ and CZ are less than 1 micrometer in diameter. It is likely that RZ corresponds to the posterior commissure while CZ corresponds to the tectal commissure.     

Death of developing septal cholinergic neurons following NGF withdrawal in vitro: protection by protein synthesis inhibition

Fetal septal neurons were grown in vitro under glass coverslips. This sandwich culture method significantly increased general neuronal survival, reduced glial proliferation, and permitted the removal of serum from the growth medium after 5 d in vitro. Thereafter, a simple, and completely defined, medium was used, and the effects of NGF, NGF withdrawal, and protein synthesis inhibition were examined on septal cholinergic neurons. NGF added to septal cultures at the time of plating resulted in a threefold increase in the number of cholinergic neurons seen at 14 d in vitro but had no effect on the survival of non-cholinergic cells. Cholinergic neurons identified by staining for AChE, ChAT, and p75NGFR could be maintained in serum-free, NGF-supplemented medium for over 40 d. When NGF was removed and NGF antibodies added to 14-d-old cultures, less than 30% of cholinergic neurons survived a further 4 d, but when NGF was similarly withdrawn from 35-d-old cultures, over 75% of cholinergic neurons survived. Reapplication of NGF after 3 but not after 12 or more hours of NGF withdrawal from 14-d-old cultures prevented the death of most cholinergic neurons. When NGF was withdrawn from 14-d-old cultures in the presence of the protein synthesis inhibitor cycloheximide, over 75% of the cholinergic neurons survived. These findings suggest that septal cholinergic neurons are dependent on NGF for survival only during a critical period of development and that growth factor-regulated developmental cell death may occur in CNS neurons by activation of programmed cell death requiring protein synthesis.     

Gentamicin-resistant menadione and hemin auxotrophic Staphylococcus aureus persist within cultured endothelial cells

Staphylococcus aureus menadione and hemin auxotrophs, generated by in vitro gentamicin selection, demonstrated reduced hemolytic activity and enhanced intracellular survival within cultured bovine aortic endothelial cells relative to their hemolytic parent. Supplementation of the auxotrophs with exogenous menadione or hemin resulted in rapid growth, increased hemolytic activity, and reduced intracellular persistence to the level found for the hemolytic clinical parent. Aminoglycoside selection of staphylococcal menadione and hemin auxotrophs and subsequent persistence of these variants in the intracellular milieu may adapt S. aureus for evasion of host defenses and resistance to antimicrobial therapy.     

Effects of chloroquine and its enantiomers on the development of rat embryos in vitro

Methods that have been proposed for mixed dentition analysis are reviewed. Prediction of the space required in the dental arch for unerupted permanent canines and premolars has been based either on the correlation between the mesio-distal widths of these teeth and of erupted mandibular incisors, or on measurements of the unerupted teeth on radiographs. Studies comparing the different methods have shown that the method of Hixon & Oldfather (1958), as refined by Staley & Kerber (1980), is the most accurate.     

Serosurvey of human immunodeficiency virus, hepatitis B virus, and hepatitis C virus infection among hospital-based surgeons. Serosurvey Study Group

BACKGROUND: Because occupational blood contact places health-care workers at risk for infection with bloodborne pathogens, we wanted to estimate the prevalence of infection with human immunodeficiency virus (HIV), hepatitis B virus (HBV), and hepatitis C virus (HCV) among hospital-based surgeons and correlate the results with occupational and nonoccupational risk factors. STUDY DESIGN: All surgeons in training or in practice in general surgery, obstetrics and gynecology, or orthopedics at 21 hospitals in moderate to high AIDS incidence areas were eligible to participate in a voluntary, anonymous serosurvey. Serum samples were tested for HIV antibody, for HCV antibody, and for markers of HBV infection: hepatitis B surface antigen, total antibody to hepatitis B core antigen, and antibody to hepatitis B surface antigen. RESULTS: Of 2,887 eligible surgeons, 770 (27 percent) participated in the study. One of 740 surgeons not reporting nonoccupational risk factors was HIV seropositive (0.14 percent, upper limit 95 percent confidence interval [CI] equals 0.64 percent). None of 20 participants reporting nonoccupational HIV risk factors and none of ten not responding to the question on nonoccupational risk factors were HIV positive. Of 129 (17 percent) participants with past or current HBV infection, three (0.4 percent) had chronic HBV infection; all were negative for hepatitis B e antigen. Risk factors for HBV infection included not receiving hepatitis B vaccine (odds ratio [OR] 14.7, 95 percent CI 8.3 to 26.0) and practicing surgery at least ten years (OR 2.2, 95 percent CI 1.3 to 3.8). Seven (0.9 percent) participants had anti-HCV. CONCLUSIONS: Although not necessarily generalizable to all surgeons in moderate to high AIDS incidence areas, these results do not indicate a high rate of previously undetected HIV infection among surgeons who trained or practiced in these areas, or both. Hepatitis B virus posed the highest risk of infection with a bloodborne pathogen, followed by HCV and HIV.     

Synthesis and antiplatelet effects of omega-aminoalkoxylxanthones

A series of omega-aminoalkoxylxanthones were synthesized and tested in-vitro for their ability to inhibit aggregation of rabbit washed platelets and human platelet-rich plasma (PRP) induced by various inducers. Nine of these compounds showed more potent antiplatelet effects than natural norathyriol tetraacetate on collagen-induced aggregation. The various omega-aminoalkoxyl side chains of the synthesized compounds modified the antiplatelet effects. All the compounds tested in human PRP showed significant inhibition of secondary aggregation induced by adrenaline, suggesting that the antiplatelet effects of these compounds is mainly due to an inhibitory effect on thromboxane formation. These compounds at high concentration also cause vasorelaxing action in rat thoracic aorta.     

Apocrine adenosis: a precursor of aggressive breast cancer?

AIM: To investigate overexpression of c-erbB2, expression of the p53 protein product and proliferation rates in benign breast lesions with specific reference to apocrine adenosis. METHODS: Twenty one cases of apocrine adenosis were stained with monoclonal antibodies to p185, the protein product of the c-erbB2 oncogene, the protein product of the p53 tumour suppressor gene and to the cell cycle related protein Ki67. Three cases were associated with concomitant ductal carcinoma in situ of large cell type and two were associated with invasive tubular or cribriform carcinoma. RESULTS: Twelve (57.1%) cases showed membrane staining for c-erbB2 oncoprotein of apocrine cells within sclerosing adenosis and six (28.6%) had occasional p53 protein positive cells. One case not associated with carcinoma showed extensive staining of apocrine metaplasia outside the area of apocrine adenosis. The proliferation rate, as measured by Ki67 staining, was increased in some of the lesions and all lesions showed at least some of the cells to be in the cell cycle. CONCLUSIONS: The expression of abnormal oncogene products and increased proliferation in some of these apocrine lesions questions the supposed degenerative nature of the atypia seen in such cases and suggests that there may be an association between these lesions and large cell ductal carcinoma in situ and hence invasive carcinoma.