Enzymatic modification of the lymphocyte surface

Lymphocytes were treated with hydrolytic enzymes primarily to assess whether such modified cells would give improved cytotoxicity reactions during tissue typing. Papain-treated and alpha-chymotrypsin-treated lymphocytes were approximately twice as sensitive as untreated cells in the microcytotoxicity test used, and this finding might be usefully exploited by immunological laboratories for purposes of cross-matching, HLA antibody screening and HLA-DR typing. Trypsin treatment promoted massive cell clumping, while neuraminidase treatment was responsible for indiscriminate cell death after exposure to rabbit serum. The capacity of lymphocytes to form rosettes with sheep erythrocytes was abolished after treatment with trypsin or alpha-chymotrypsin, but enhanced by papain or neuraminidase.     

Laboratory compliance with federal government and professional society recommendations

Quality assurance issues have assumed growing importance in the cytology laboratory. The 1988 Clinical Laboratories Improvement Amendment (CLIA '88) (United States Department of Health and Human Services, Federal Register: U.S. Government Printing Office 1990;55:9495) regulates the patient identifiers and clinical data on the requisition form but does not mandate physician compliance to provide the information. We investigated the use of patient identifiers and clinical data by laboratories as specimen acceptance/rejection criteria. We surveyed 81 board certified cytopathologists and 235 randomly selected cytology laboratories for acceptance criteria of cytology specimens and received responses from 104. Approximately two thirds of all responding laboratories had specific criteria for rejecting specimens on the basis of inadequate identification or clinical data. While the vast majority required the specimens to be identified with patient name, collection date, and specimen source, a minority of laboratories required clinical information such as LMP, prior atypical cytologic/histologic specimens, and history of previous therapy. Little correlation was found between practice setting and the use of rejection criteria. Diagn Cytopathol 1994; 11:85–92. © 1994 Wiley-Liss, Inc.     

Cefoxitin as a single-dose treatment for urethritis caused by penicillinase-producing Neisseria gonorrhoeae.

Gonococci that resist standard penicillin regimens by production of a penicillinase are now well established in certain areas of the world. Because cefoxitin, a semisynthetic cephamycin, resists gonococcal penicillinase in vitro, we compared procaine penicillin G and cefoxitin in treatment of gonorrhea in an area where 40 per cent of isolates produce penicillinase. One hundred and seven men with culture-proved gonococcal urethritis were given a single dose of either procaine penicillin G, 4.8 million U, or cefoxitin, 2 g, intramuscularly. Both groups took 1 g of probenecid orally; cefoxitin was given with lidocaine to reduce pain at the injection site. In men infected with penicillinase-negative gonococci, both cefoxitin and penicillin were highly effective. Penicillin failed in 77 per cent of men with penicillinase-positive strains, whereas cefoxitin was completely successful. Cefoxitin is an effective alternative to spectinomycin for single-session therapy of urethritis caused by penicillinase-producing Neisseria gonorrhoeae.     

Estimation of size of clonal unit for keratinocytes in normal human skin

OBJECTIVE: It has been suggested that keratinocyte (KC) stem cells reside at the epicenter of a clonal population of cells. To estimate the territory or surface area covered by a single stem-cell-derived KC population in human skin, clonal skin maps were created from 3 healthy adult women and from normal skin of a psoriatic patient. DESIGN: Two hundred fifty-eight punch biopsy samples of various sizes (ranging from 2 to 8 mm in diameter) were analyzed for clonality employing X chromosome inactivation patterns at the human androgen receptor gene (HUMARA) locus. DNA was isolated and clonality established by significant decrease of either maternal or paternal X chromosome band patterns following restriction enzyme digestion, polymerase chain reaction amplification, and gel electrophoresis. RESULTS: Fifty-three (41%) of 128 two-mm biopsies were clonal, whereas only 6 (14%) of 43 three-mm, 5 (14%) of 36 four-mm, and 3 (8%) of 35 five-mm biopsies revealed a clonal population of KCs. By contrast, in 5 different biopsies from a psoriatic patient, including 4- or 5-mm sizes, all but 1 were clonal; even an 8-mm biopsy contained a clonal population of KCs. Mantel-Haenszel chi(2) analysis revealed a P value of.001, reflecting a strong trend in probability for presence of a single clone of KCs as related to size of the biopsy sample. By sequentially analyzing 30 contiguous 2-mm biopsy samples within a given strip of skin, 10 clonal domain changes, as reflected in maternal versus paternal switches, were observed. CONCLUSIONS: These results provide direct evidence of a clonal population of KCs in normal and psoriatic lesion-free skin, and indicate that a clonal epidermal unit of KCs frequently can be detected in small biopsies (2 mm), but that in normal skin sampling, overlapping clones are apparently present in larger (ie, 4-5-mm) biopsies, producing nonclonal patterns. The clonal domain of progeny in normal skin has a rather limited territorial boundary (2 mm in diameter). However, in lesion-free skin from a psoriatic patient, there may be clonal expansion of KCs due to perturbation in epidermopoiesis and/or stem cell distribution.     

The MD-MPH program at the University of North Carolina at Chapel Hill.

In 1997, the Schools of Medicine and Public Health at the University of North Carolina at Chapel Hill (UNC) developed a formal MD-MPH program, called the Health Care and Prevention (HC&P) Program, located in the Public Health Leadership Program in the UNC School of Public Health. Since then, and especially since 2003, the number of UNC medical students taking a year out of their medical studies to pursue an MPH has increased dramatically. At present, more than 20% of UNC medical students enter an MPH program at some point between entering medical school and leaving for residency.The HC&P Program is designed to introduce clinicians to the population sciences and to create physicians who can think in both individual and population terms. The curriculum is a rigorous, 12-month program that includes a practicum experience and a master's paper. Several of the traditional MPH introductory courses have been redesigned to be more relevant to physicians. The program allows a maximum number of electives and places a value on flexibility so that students, together with faculty, can design the educational experience that best meets their needs. Many members of the faculty of the program themselves have both MD and MPH degrees, and some have dual appointments in the schools of medicine and public health.The authors have begun a longitudinal cohort study of program graduates and other medical graduates to understand the effect of the program on students' perceptions of their competency and their ability to exert leadership in various areas of population health.     

Amino acid uptake required for long-term memory formation

α-Amino-iso-butyrate (AIB) inhibits long-term, protein synthesis-dependent memory formation by reducing labelled leucine uptake in vivo without affecting leucine incorporation into protein. Unlike the antibiotic cycloheximide, AIB does not block long-term memory formation through inhibition of protein synthesis per se. The behavioural effect of AIB is restricted to times of administration between 5 min before and 5 min after learning a single trial passive avoidance task by day-old chickens. It is concluded that (1) AIB competes with normal amino acids for uptake into cells, and (2) the uptake of amino acids for protein synthesis specific to long-term memory formation takes place in the first few minutes following learning.