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Biomedical subjects

J L Allen

Publications and source records attributed to J L Allen.

At least 91 records · Page 5Linked to original sources
PubMed1979

Gas-liquid chromatographics determination of Bayer 73 in fish, aquatic invertebrates, mud, and water.

A gas-liquid chromatographic (GLC) method is described for determining residues of Bayer 73 (2-aminoethanol salt of 2',5-dichloro-4'-nitrosalicylanilide) in fish muscle, aquatic invertebrates, mud, and water by analyzing for 2-chloro-4-nitroaniline (CNA), a hydrolysis product of Bayer 73. Bayer 73 residues are extracted from fish muscle tissue, invertebrates, and mud with acetone-formic acid (98+2), and partitioned from water samples with chloroform. After sample cleanup by solvent and acid-base partitioning, the concentrated extract is hydrolyzed with 2N NaOH and H2O2 for 10 min at 95 degrees C. The CNA is then partitioned into hexane-ethyl ether (7+3) and determined by electron capture GLC. Average recoveries were 88% for fish, 82% for invertebrates, 82% for mud, and 98% for water at 3 or more fortification levels.

Animals↗
PubMed1978

Cell-mediated immunity in diabetes mellitus.

Cell-mediated immunity was evaluated in patients with diabetes mellitus by delayed hypersensitivity skin tests and in vitro lymphocyte transformations. Only 44% of diabetic patients had skin test reactivity to Candida antigen, compared with 88% of normal controls (P < 0.001). Insulin-dependent diabetic (IDD) patients had abnormally low lymphocyte transformation responses to phytohemagglutinin, concanavalin A, and streptokinase-streptodornase (P < 0.05). This defect was not corrected by culturing the cells in nondiabetic plasma. IDD patients with persistent hyperglycemia (fasting serum glucose level, >200 mg/dl) had lower levels of transformation than did IDD patients with fasting serum glucose levels less than 150 mg/dl. Lymphocytes from two IDD patients with poor lymphocyte transformation responses had marked improvement in response to phytohemagglutinin when the lymphocytes were cultured after a preincubation period designed to deplete cultures of suppressor activity. Seven IDD patients were studied serially over 12 months. Lymphocyte transformation responses in four of these patients improved coincidentally with a change in the level of fasting hyperglycemia from >200 to <150 mg/dl. The other three IDD patients with consistent fasting serum glucose levels of >200 mg/dl had poor lymphocyte transformation responses. Diabetic patients have demonstrable defects in lymphocyte function which improved in a small number of patients with reduction in the level of fasting hyperglycemia.

Adolescent↗
PubMed1978

Astigmatism and acuity in two primate infants.

The development of grating acuity was followed in two astigmatic primate infants, one a human being and one a pigtail macaque monkey. Both infants showed variations of acuity with grating orientation, predictable from the orientation and type of astigmatism present. Optical correction of the human infant during testing virtually eliminated the variation of acuity with orientation, suggesting that a neurally based meridional amblyopia had not yet been established.

Age Factors↗
PubMed1970

Vibriolytic antibody-forming cells: a new application of the Pfeiffer phenomenon.

Complement-mediated immune lysis was first described by Pfeiffer after observing an immune reaction against Vibrio cholerae. Application of this reaction in agar gel, with viable vibro organisms, gave results which were unique compared to the red blood cell or enterobacterial systems. Among these was the lack of a detectable "background," a lengthened latent period and differentiable results among the three major cell wall antigens characteristic of this bacterial groups.

Animals↗
PubMed1964

Bacteria under simulated Martian conditions.

The behavior of organisms in simulated Martian conditions is of great importance to exobiology for two reasons: (1) Because of the extreme environment of Mars, the likelihood of contamination of the planet by earth organisms is considered slight by some scientists. To date, there has been little evidence to contradict this supposition. Such evidence is presented. (2) The selection and adaptation of earth bacteria to Martian conditions is potentially significant in understanding Martian life, if it exists, and may be helpful in designing life-detection techniques and devices. Of course, simulation attempts, based on current knowledge of the Mars environment, may be far from the actual conditions, and extrapolations made from such situations of no real significance. However, generalizations can be made and cautious interpretation of the results of those experiments seems well worth reporting. A new technique for simulation of known parameters of the Martian environment is discussed along with possible biological implications. The response of bacteria to such simulation is demonstrated in terms of survival and growth, showing that certain bacteria will not only survive, but grow during simulated Martian freeze-thaw cycling if water is present. Ways are demonstrated in which water can be present on Mars although not detectable with current technology. Plans for future experimentation are discussed.

Enterobacter aerogenes↗
PubMedDate not supplied

Synthesis of beta2 glycoprotein 1 by the human placenta.

Autoantibodies to negatively charged phospholipids (aPL) can cause fetal loss, including recurrent miscarriage and stillbirth. The immunopathogenic mechanism by which this occurs is unknown, but these antibodies are known to bind phospholipid via a protein cofactor, beta2 glycoprotein 1. This protein is localized on placental syncytiotrophoblast and enables the binding of aPL from maternal blood. In this study, reverse transcription and the polymerase chain reaction (RT-PCR) was used on mRNA isolated from normal human placental villous tissue and from human choriocarcinoma cell lines (Jeg-3, BeWo and JAr) to demonstrate that placental cells themselves synthesize beta2 glycoprotein 1 transcripts. Protein production was confirmed by immunoblotting experiments. Previous immunohistochemical studies were extended to demonstrate that beta2 GP1 is localized to extravillous cytotrophoblast in addition to syncytiotrophoblast. Production of beta2 glycoprotein 1 by fetal trophoblast indicates this protein is likely to have a physiological function in the placenta, and hence aPL may induce their pathological effect in pregnancy by inhibiting the function of placental beta2 glycoprotein 1.

Cell Line↗