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Biomedical subjects

J W Harris

Publications and source records attributed to J W Harris.

At least 55 records · Page 3Linked to original sources
PubMed1993

Pyridoxine responsive hereditary sideroblastic erythropoiesis and iron overload: two microcytic subpopulations in the affected male, one normocytic and one microcytic subpopulation in the obligate female carrier.

Mild hepatic iron overload has been demonstrated by magnetic susceptibility measurements in a 22-year-old man with hereditary sideroblastic erythropoiesis despite hemoglobin levels in the normal range and a normal erythropoietin level. His grandfather's sideroblastic anemia has been found to be responsive to pyridoxine; his mother's hemoglobin has persisted in the normal range but red cell volume distribution analysis demonstrated two subpopulations; 30% with estimated geometric mean of 68 fl and 70% an estimated mean of 93 fl. Red cell distribution analysis of the grandson demonstrated two microcytic subpopulations; 46% with an estimated geometric mean of 45 fl and 54% an estimated mean of 70 fl. A therapeutic regimen is outlined to reduce to normal his iron stores and to prevent the future development of excessive iron overload.

Adolescent↗
PubMed1992

Synthesis of [2-3H-ethyl]S-(2-chloro-1,1,2-trifluoroethyl)-L-cysteine and its use in covalent-binding studies.

Metabolism of S-(2-chloro-1,1,2-trifluoroethyl)-L-cysteine (CTFC) yields chlorofluorothioacetyl fluoride, which reacts with cellular proteins to form stable lysine adducts. Little is known about the subcellular localization of these protein adducts or about their role in CTFC-induced nephrotoxicity. A method for the synthesis of CTFC and other cysteine S-conjugates labeled with 3H at the S-alkyl or S-alkenyl position would be useful in studies of S-conjugate metabolism and toxicity. Reaction of L-cysteine, chlorotrifluoroethene, 1,8-diazabicyclo[5.4.0]undec-7-ene, and 3H-labeled water followed by repeated crystallization yielded radiochemically pure [3H]CTFC (235 mg, 20% yield; sp act 1.07 x 10(9) Bq/mmol), which was identical to CTFC by TLC, 1H NMR, and 19F NMR. 3H NMR revealed a doublet of triplets at 6.5 ppm with geminal and vicinal T-F couplings of 51.5 and 6.0 Hz, respectively, consistent with the proposed structure. When 2H-labeled water was used, [2H]CTFC was formed, and its structure was confirmed by 1H and 19F NMR, FAB-MS, and TLC. Analysis of renal and hepatic subcellular fractions of rats given 1, 10, or 100 mumol/kg [3H]CTFC showed a dose-dependent binding of 3H-containing metabolites to liver and kidney proteins.

Animals↗
PubMed1992

A study of neuropathy in HIV infection.

A prospective study of possible aetiological factors for neuropathy associated with HIV infection was performed in 80 patients and 28 homosexual controls. At entry to the study twelve patients (15 per cent) had evidence of a generalized neuropathy not due to any other cause and a further three patients developed symptomatic neuropathy during a mean (SD) follow-up of 20 (7.5) months. All but two of these neuropathies were of the distal symmetrical sensory type. Electrophysiology was consistent with an axonal pathology and nerve biopsy confirmed this as the major pathological change. Warming threshold was the diagnostic test most frequently abnormal, sometimes in the absence of other electrophysiological abnormalities. No association was seen with opportunistic infection (cytomegalovirus, herpes simplex, Pneumocystis pneumonia, toxoplasmosis, Cryptococcus infection or tuberculosis). HIV proviral DNA could not be detected in paraffin sections of peripheral nerve in six patients with neuropathy. The presence of the neuropathy did not show significant correlation with depression of the number of CD4+ T cells in the blood, impaired T cell function tests, or IgG, IgM, or IgA levels. Immune complexes containing C1q, but not those containing IgG, IgM, IgA or C3c, were significantly more common among neuropathic patients (p = 0.01).

AIDS-Related Opportunistic Infections↗
PubMed1991

Tissue acylation by the chlorofluorocarbon substitute 2,2-dichloro-1,1,1-trifluoroethane.

Hydrochlorofluorocarbons (HCFCs) are being developed as substitutes for ozone-depleting chlorofluorocarbons (CFCs); because widespread human exposure to HCFCs may be expected, it is important to evaluate their toxicities thoroughly. Here we report studies on the bioactivation of the CFC substitute 2,2-dichloro-1,1,1-trifluoroethane (HCFC-123) to an electrophilic intermediate that reacts covalently with liver proteins. HCFC-123 and its analog halothane (2-bromo-2-chloro-1,1,1-trifluoroethane) were studied in rats by 19F NMR spectroscopy, and we found that a trifluoroacetylated lysine adduct was formed with liver proteins. Also, the pattern of proteins immunoreactive with hapten-specific anti-trifluoroacetylprotein antibodies was identical in livers of HCFC-123- and halothane-exposed rats. Because halothane causes an idiosyncratic, and sometimes fatal, hepatitis that is associated with an immune response against several trifluoroacetylated liver proteins, the present findings raise the possibility that humans exposed to HCFC-123 or structurally related HCFCs may be at risk of developing an immunologically mediated hepatitis.

Acylation↗
PubMed1991

Mononeuropathy in sickle cell anemia: anatomical and pathophysiological basis for its rarity.

Peripheral neuropathy is a rare complication of sickle cell disease. We report a young black woman with sickle cell anemia who developed a proximal median mononeuropathy in the setting of sickle cell crisis. The clinical and electrodiagnostic features are consistent with an ischemic mechanism from the sickling process. The pathophysiological basis for the rarity of this complication may be related to the rich anastomotic microvasculature of peripheral nerve and the unique large size of the capillaries of this vascular network.

Adult↗
PubMed1991

Comparing serum ferritin values from different population surveys.

This report compares serum ferritin data collected in recently conducted Health and Nutrition Examination Surveys by age, sex, and ethnic group. Serum ferritin assays and selected confounding variables are examined to explore the basis of the difference in serum ferritin values obtained from the different surveys.

Confounding Factors, Epidemiologic↗
PubMed1990

Radiation therapy for AIDS-related Kaposi's Sarcoma.

Between March 1982 and October 1987, 375 fields in 187 patients with AIDS-related Kaposi's Sarcoma were treated in the Department of Radiation Oncology at the University of California in San Francisco (UCSF). Field sizes ranging from 2 x 2 cm to total skin received doses of 8 Gy in a single fraction to 15-40 Gy in 5-10 fractions. Seventy-four percent of the patients have died. Response to treatment was achieved in over 90% of treated fields, with a median time to progression of 21 months and an actuarial freedom from relapse at 6 months of 69% (97 patients alive). There was no difference in outcome regardless of the fractionation regimen used. Severe reactions were noted in 17% of treated fields, but this incidence was significantly lower when a single fraction of 8 Gy was used (p less than 0.001). Radiation therapy plays an important palliative role in this devastating disease. This review supports the use of a single 8 Gy fraction for all Kaposi's Sarcoma lesions of the skin. Further data regarding single fraction therapy for lesions of other sites are needed.

Acquired Immunodeficiency Syndrome↗
PubMed1990

Rheologic properties of mixed hemoglobin gels: deoxyhemoglobins S and F.

To obtain new information concerning the behaviors--and in turn, the structures--of gels formed from mixtures of S and F hemoglobins, their rheologic properties have been characterized by stress relaxation. The variables manipulated were (1) initial total hemoglobin concentration; (2) mole fraction of hemoglobin S present in the mixture; (3) hemoglobin F as only intact tetramer or as both tetramers and hybridized hemoglobin; (4) hemoglobin F as predominantly G gamma, A gamma, or a mixture of gamma chain types; (5) annealing time; (6) shear history, (7) temperature; and (8) temperature and time of annealing. Characteristics monitored to gain information about the effect of these variables on gel properties were (1) lag time, (2) polymer mass, (3) polymer fraction, (4) polymer composition, (5) equilibrium total hemoglobin activity, and (6) solidity/total or hemoglobin S polymer mass (or total or hemoglobin S fraction). As expected, mixed hemoglobin S and F gels were less solid than pure hemoglobin S gels of similar initial total hemoglobin concentrations because of lower polymer mass, and gel properties were influenced by annealing time, shear history, temperature, and temperature and time of annealing. However, when solidities were compared on the basis of similar quantities of gel present, mixed hemoglobin S and F gels were found to be more solid than those of pure S as the mole fraction of hemoglobin S decreased in the initial mixture. This is explained by the predominant influence on gel properties of high hemoglobin activity incurred by the volume exclusion effect of the total hemoglobin concentration. Pathophysiologic implications of these findings for various sickle cell disorders are proposed.

Anemia, Sickle Cell↗
PubMed1990

Rheologic properties of mixed hemoglobin gels: deoxyhemoglobins S and A.

To obtain new information concerning the behaviors, and in turn the structures, of gels formed from mixtures of S and A hemoglobins, their physical properties have been characterized by stress relaxation with a rotational rheometer. The variables manipulated were (1) initial total hemoglobin concentration, (2) mole fraction of hemoglobin S present in the mixture, (3) hemoglobin A as intact tetramer only or as both tetramer and hybridized hemoglobin AS, (4) annealing time, (5) shear history, (6) temperature, and (7) temperature and time of annealing. Characteristics monitored to gain information about the effect of these variables on gel properties were (1) lag time, (2) polymer mass, (3) polymer fraction, (4) polymer composition, (5) equilibrium total hemoglobin activity, and (6) solidity/total or hemoglobin S polymer mass (or total or hemoglobin S fraction). As expected, mixed hemoglobin SA gels were less solid than those of pure S of similar initial hemoglobin concentrations because of lower polymer mass, and gel properties were influenced by shear history, annealing time, temperature, and temperature and time of annealing. However, when solidities were compared on the basis of similar quantities of gel present, mixed hemoglobin SA gels were found to be more solid than those of pure S as the mole fraction of hemoglobin S decreased in the initial mixture. This is explained by the predominant influence on gel properties of high hemoglobin activity incurred by the volume exclusion effect of the total hemoglobin concentration. The presence of hemoglobin A with hemoglobin S results in polymers and gels that differ from those found in pure hemoglobin S. Pathophysiologic implications of these findings for sickle cell disorders are proposed.

Anemia, Sickle Cell↗
PubMed1988

Upper gastrointestinal Kaposi's sarcoma in patients positive for HIV antibody without cutaneous disease.

Six patients with antibodies to the human immunodeficiency virus (HIV) and with persistent gastrointestinal symptoms of HIV infection but without cutaneous lesions of Kaposi's sarcoma underwent endoscopy. Four also underwent barium meal examination. In all six cases small lesions were seen in the stomach at endoscopy, and histological examination of biopsy specimens taken from the lesions confirmed the diagnosis of Kaposi's sarcoma. The barium meal examinations were reported as normal in three patients and showed oesophageal candidiasis in the fourth. These findings suggest that Kaposi's sarcoma of the upper gastrointestinal tract is common in patients positive for HIV antibody, even those without cutaneous lesions. Endoscopy, with biopsy of suspicious lesions, is necessary to make the diagnosis and is recommended in all HIV antibody positive patients with persistent upper gastrointestinal symptoms.

Adult↗
PubMed1987

Rheologic behavior of deoxyhemoglobin S gels.

The physical properties of deoxyhemoglobin S gels formed from solutions at concentrations and temperatures approaching those in vivo have been characterized by stress relaxation using a rotational rheometer. Gels were annealed in the rheometer and then subjected to a constant shear strain; thereafter the stress sustained was followed with time. Gels with solid-like behavior held stress indefinitely, and were characterized by yield temperature (the temperature at which stress decreased). Gels with less solid behavior were unable to hold target stress, and were characterized by yield stress (maximum stress attained) and equilibrium stress (final stress held). The samples were ultracentrifuged to calculate pellet and polymer masses. The solidity of the gels, as measured by yield temperature or yield stress, was related to the initial hemoglobin concentration, pellet and polymer masses, shear history, temperature, and the temperature and time of annealing. Solidity increased significantly with time when gels were annealed at 37 degrees C, whereas, when annealed at 25 degrees C, no or minimal increases in solidity were noted. Studies suggest that polymerization occurs rapidly and is completed early in or before the gel annealing period and that the increase in solidity with time of annealing is mainly due to factors other than polymer mass, i.e. alignment, increasing bond strength, water loss. The chemical activity of deoxyhemoglobin S did not affect the solidity of the formed gels. When the resultant polymer masses were comparable, gels formed from samples with albumin present (higher initial total protein concentration, but lower initial deoxyhemoglobin S concentration), had the same behavior as gels formed from solutions with higher initial hemoglobin S concentration. These findings demonstrate that gel annealing conditions must be standardized when comparing the rheologic behaviors of deoxyhemoglobin S gels and indicate that the gel's physical properties (influenced by polymer mass, shear history, annealing time) must be considered in understanding pathophysiology of sickling disorders.

Amino Acid Sequence↗
PubMed1986

Calcium-dependent inhibition of the erythrocyte Ca2+ translocating ATPase by carbodiimides.

The ATP hydrolytic activity of the solubilized and purified Ca2+-translocating ATPase from human erythrocyte plasma membrane was strongly inhibited by the nonpolar compound, N,N'-dicyclohexylcarbodiimide, both in the presence and in the absence of calmodulin. However, the more water-soluble carbodiimides, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide and 1-cyclohexyl-3-(2-morpholinoethyl)carbodiimide had little inhibitory effect on the enzyme. The inhibitory effect of N,N'-dicyclohexylcarbodiimide was most pronounced at acid pH, and declined sharply at alkaline pH values. In addition, the optimum pH for the enzyme activity also shifted to more alkaline values in the presence of the carbodiimide. Calcium ion appears to favor the inhibition induced by the carbodiimide, in contrast to the observed protection by Ca2+ in the sarcoplasmic reticulum Ca2+-translocating ATPase. N,N'-Dicyclohexylcarbodiimide also dramatically decreased the stimulatory effect of calmodulin on the activity of the enzyme.

Adenosine Triphosphate↗