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Biomedical subjects

C A Hall

Publications and source records attributed to C A Hall.

At least 19 recordsLinked to original sources
PubMed1994

Delayed-type hypersensitivity anergy in human immunodeficiency virus-infected persons screened for infection with Mycobacterium tuberculosis.

A total of 479 human immunodeficiency virus (HIV)-infected persons at an HIV clinic in Florida and a tuberculosis clinic in New Jersey were skin-tested with tuberculin, tetanus toxoid, mumps antigen, and Candida antigen in a study of the prevalence of delayed-type hypersensitivity (DTH) anergy and the usefulness of two-step tuberculin testing in this population. Of the patients tested, 12% had a positive (> or = 5-mm) response to tuberculin; 57%, 45%, and 35% had a positive (> or = 3-mm) response to Candida antigen, tetanus toxoid, and mumps antigen, respectively; and 31% were anergic (< 3 mm of induration in response to each antigen). In a multivariate logistic regression model, anergy was significantly associated with a history of Kaposi's sarcoma, Pneumocystis carinii pneumonia, or oral candidiasis and with White race. Anergy was four times and 15 times as likely for persons with CD4+ T-lymphocyte counts of 200-400/mm3 and < 200/mm3, respectively, as for persons with > 499 CD4+ T lymphocytes/mm3. Of 103 patients who were tuberculin-tested a second time after their initial test result was negative, seven had > or = 5 mm of induration in response to the second test; only one of these patients was anergic at the initial screening. The findings of this study indicate that DTH antigens should be used in conjunction with tuberculin testing and that two-step tuberculin testing is not an alternative to anergy testing but may be useful for the detection of infection with Mycobacterium tuberculosis in nonanergic HIV-infected patients.

AIDS-Related Opportunistic Infections↗
PubMed1992

Heterogeneity in cblG: differential retention of cobalamin on methionine synthase.

Cultured fibroblasts from patients with functional methionine synthase deficiency have been shown to belong to two complementation classes, cblE and cblG. Both are associated with decreased intracellular levels of methylcobalamin (MeCbl) and decreased incorporation of label from 5-methyltetrahydrofolate into macromolecules. Methionine synthase specific activity is normal or near normal in cell extracts from cblE patients under standard reducing conditions, whereas specific activity is low in cblG extracts. Seven of 10 cblG cell lines accumulated [57Co]CN-Cbl equivalent to control cells and showed similar proportions of label associated with the two intracellular cobalamin binders, methionine synthase and methylmalonyl-CoA mutase. The remaining three cblG lines showed reduced accumulation of labeled Cbl and virtually none associated with methionine synthase. The specific activity of methionine synthase was decreased in cell extracts from both cblG subgroups, being almost undetectable in extracts from the latter three lines. Incorporation of label from [14C]MeTHF into either macromolecules or into methionine was decreased in both cblG groups, but was paradoxically higher in the three lines with very low in vitro methionine synthase activity. These results demonstrate further heterogeneity within cblG and suggest that the defect in the three variant lines affects the ability of methionine synthase to retain Cbl.

5-Methyltetrahydrofolate-Homocysteine S-Methyltran↗
PubMed1992

The neurologic aspects of transcobalamin II deficiency.

Thirty-four symptomatic cases of inherited transcobalamin II (TCII) deficiency were analysed in order to determine the frequency and nature of neurologic manifestations. In no instance was there definite evidence of a neurologic disorder at the time of presentation as a young infant. One child of 2 1/2 years transiently lost deep tendon reflexes at a time of suboptimal treatment. A syndrome of mental retardation and other neurologic manifestations was observed in three cases, all with the following in common: (1) an extended duration of illness of 2-17 years; (2) inadequate or not treatment with Cbl; (3) treatment with folic of folinic acid. TCII deficiency rarely if ever presents with neurologic manifestations. However, neurologic disorders can be produced subsequently by improper treatment.

Central Nervous System Diseases↗
PubMed1992

Rescue angioplasty during myocardial infarction has a beneficial effect on mortality: a tenable hypothesis.

HYPOTHESIS: Rescue percutaneous transluminal coronary angioplasty (PTCA) reduces mortality during myocardial infarction. OBJECTIVE: To determine if PTCA after failed thrombolytic therapy results in reduced mortality. DESIGN: Twenty-eight patients with a persistently occluded infarct artery following thrombolytic therapy more than 3 h after symptom onset were randomized to rescue PTCA (n = 16) or conservative treatment (n = 12) as part of a prospective randomized trial of reperfusion therapy during myocardial infarction in 184 patients. Hospital mortality was assessed in these groups as well as in the 177 patients with known infarct artery status after initial attempts at reperfusion. MAIN RESULTS: There was one death among the 16 patients in the rescue PTCA group versus four deaths in the 12 patients treated conservatively (P = 0.13). Moreover, the death in the rescue PTCA group occurred in one of three patients in whom the procedure failed. Mortality in the entire study group was 10.3% (19 of 184); 4.2% (six of 142) in patients in whom patency was achieved after thrombolysis and/or PTCA and 34.3% (12 of 35) in those in whom reperfusion was not achieved (P less than 0.001). In patients with anterior myocardial infarction, mortality was 6.7% (four of 60) in those with reperfusion and 47.1% (eight of 17) in those with a persistently occluded artery (P less than 0.001). In patients with inferior myocardial infarction, 2.4% (two of 82) with reperfusion and 22.2% (four of 18) with a persistently occluded artery died (P less than 0.01). CONCLUSIONS: Although the number of patients in the randomized groups was small, the trend toward a lower mortality after rescue PTCA supports the hypothesis that rescue PTCA may be beneficial. The mortality results in relation to presence or absence of reperfusion from the entire study population underscores the importance of achieving patency during myocardial infarction.

Aged↗
PubMed1991

Transcobalamin II deficiency: case report and review of the literature.

A male Caucasian infant presented at 6 weeks of age with failure to thrive, diarrhoea, macrocytic anaemia, and decreased IgG. He had normal serum B12 and folate levels. Serum cobalamin binding capacity showed no detectable transcobalamin II. Both parents showed levels consistent with a heterozygous state. The literature is extensively reviewed, and the importance of early diagnosis to prevent neurological dysfunction is stressed.

Failure to Thrive↗
PubMed1991

Relation between flow grade after thrombolytic therapy and the effect of angioplasty on left ventricular function: a prospective randomized trial.

Recent intervention trials during myocardial infarction demonstrated no benefit from emergency angioplasty after thrombolytic therapy when compared with either delayed percutaneous transluminal coronary angioplasty (PTCA) or a conservative strategy. However, it is possible that subgroups of patients may benefit from early intervention with angioplasty. We performed a prospective randomized trial in patients with a patent infarct-related artery after thrombolytic therapy to determine whether initial flow grade is related to infarct-zone function and whether patients with ineffective reperfusion (greater than 90% stenosis or Thrombolysis in Myocardial Infarction [TIMI] flow less than or equal to 2) might benefit from immediate PTCA. Thrombolytic therapy was administered to 170 patients at a mean of 2.1 +/- 0.5 hours after onset of myocardial infarction. A patent infarct-related artery that was suitable for angioplasty was present in 89 patients who comprised the study group; after randomization, 47 of 50 patients with a patent infarct-related artery had successful emergency PTCA 3.8 +/- 1.5 hours after onset of symptoms, and 39 were scheduled for delayed (18 to 48-hour) PTCA. Reocclusion occurred before the scheduled (delayed) procedure in eight patients (20.5%), and was symptomatic in six. Infarct-region function (by the centerline method) measured initially, before discharge, and at 4 months was similar in both groups; improvement was significant (p less than 0.001) at discharge when compared with initial values with no further change at 4 months. However, patients with ineffective reperfusion had greater hypokinesia initially (p less than 0.05) compared with those with effective reperfusion (less than or equal to 90% stenosis plus TIMI flow 3). Moreover, independent of the timing of PTCA, improvement was greater before discharge in patients with ineffective reperfusion (p less than 0.05) with a trend also evident at 4 months. Importantly, 42 of 51 patients (82%) with a residual lumen less than 0.4 mm after thrombolysis had some improvement in function at discharge; this compared with a previous study in which patients with a similar degree of stenosis (without PTCA) had no improvement. Moreover, reocclusion occurred before scheduled (delayed) PTCA in 37% of patients with greater than 90% stenosis compared with only 5% in those with less than or equal to 90% stenosis (p = 0.02). Thus flow grade is an important determinant of myocardial function in patients with a patent artery after thrombolytic therapy and is predictive both of improvement in wall motion after PTCA and early reocclusion.(ABSTRACT TRUNCATED AT 400 WORDS)

Angioplasty, Balloon, Coronary↗
PubMed1991

Monoclonal antibody for avian thymic hormone.

Avian thymic hormone (ATH), a parvalbumin with immunomodulating properties, was used as antigen for development of a hybridoma cell line. Hybridoma screening by enzyme-linked immunosorbent assay (ELISA) led to the culture, purification, and characterization of an hybridoma, designated 4A6, which secretes IgG1 that is specific for ATH. The monoclonal antibody (MAb) was characterized by techniques involving indirect competitive and non-competitive ELISA, Western Blot analysis, and immunohistological staining. The MAb was highly specific for ATH with no cross-reactivity to other chicken tissue extracts or commercially available parvalbumins.

Animals↗
PubMed1991

Report on the Fourth Conference for Federally Supported Human Nutrition Research Units and Centers.

The Fourth Conference for Federally Supported Human Nutrition Research Units and Centers, sponsored by the Interagency Committee on Human Nutrition Research, addressed two topics: nutrition and function, and nutrient interactions and toxicities. This article summarizes the conference's introductory remarks and the contents of the 34 papers presented. Future meetings of federally supported nutrition research units and centers will focus on other human nutrition research topics and will be held biennially.

Humans↗
PubMed1991

Inherited selective intestinal cobalamin malabsorption and cobalamin deficiency in dogs.

Inherited selective intestinal malabsorption of cobalamin (Cbl) was observed in a family of giant schnauzer dogs. Family studies and breeding experiments demonstrated simple autosomal recessive inheritance of this disease. Affected puppies exhibited chronic inappetence and failure to thrive beginning between 6 and 12 wk of age. Neutropenia with hypersegmentation, anemia with anisocytosis and poikilocytosis, and megaloblastic changes of the bone marrow were present. Serum Cbl concentrations were low, and methylmalonic aciduria and homocysteinemia were present. Parenteral, but not oral, cyanocobalamin administration rapidly eliminated all signs of Cbl deficiency except for low serum Cbl concentrations. Cbl malabsorption in affected dogs was documented by oral administration of [57Co]cyanocobalamin with or without simultaneous oral administration of intrinsic factor or normal dog gastric juice. Quantitation and function studies of intrinsic factor and transcobalamin-II from affected dogs revealed no abnormality. Other gastrointestinal functions and ileal morphology were normal, indicating a selective defect of Cbl absorption at the level of the ileal enterocyte. Immunoelectron microscopy of ileal biopsies showed that the receptor for intrinsic factor-Cbl complex was absent from the apical brush border microvillus pits of affected dogs. This canine disorder resembles inherited selective intestinal Cbl malabsorption (Imerslund-Gräsbeck syndrome) in humans, and is a spontaneously occurring animal model of early onset Cbl deficiency.

Animals↗
PubMed1990

Determination of chloral hydrate metabolism in adult and neonate biological fluids after single-dose administration.

A simple, rapid and sensitive electron-capture gas chromatographic method has been developed for the simultaneous determination of chloral hydrate, trichloroethanol and trichloroacetic acid in biological fluids. The described method is applicable to single-dose pharmacokinetic studies of chloral hydrate in the adult. The method also meets the important requirement of using very small sample volumes and is sufficiently sensitive and reliable for disposition studies in the neonate.

Adult↗
PubMed1990

Function of vitamin B12 in the central nervous system as revealed by congenital defects.

The 13 cases of methylcobalamin (MeCbl) deficiency presenting in early infancy have all been developmentally delayed, and the majority have had seizures, hypotonia, lethargy, and microcephaly. The CNS injury appears to occur during the first 6 months of postnatal life. The same symptoms are seen in acquired cobalamin (Cbl) deficiency in the same age group. MRI performed at age 18-19 months and after 13-14 months of large amounts of Cbl, in two cases showed delayed myelination, most pronounced in the cerebrum. Isolated MeCbl deficiency is the consequence of cblE and G mutations where the lesion is of a single Cbl-dependent enzyme, the methyltransferase. One effect of a deficiency of MeCbl, and of the associated failure of the methionine synthase reaction, is, therefore, an impairment of myelination of the brain of the newborn. The slow, but usually incomplete, improvement in psychomotor status after years of treatment with Cbl may be related to the eventual myelination. However, the hypotonia, lethargy, and impaired responsiveness react to treatment with Cbl within 24-48 hours, which suggests an expression of MeCbl deficiency on the CNS distinct from the delayed myelination. Although there is much to be learned, it is now clear that a normally functioning Cbl-dependent methyl transferase is required for development and function of the human brain.

Amino Acid Metabolism, Inborn Errors↗
PubMed1990

Serum homocysteine in routine evaluation of potential vitamin B12 and folate deficiency.

Total serum homocysteine (Hcy) was measured in patients with either low serum folate, low serum vitamin B12 (B12), or potential metabolic defects, in order to evaluate Hcy as an indicator of the tissue status of the two vitamins. An increased Hcy supported the diagnosis of frank tissue deficiency in those patients in whom tissue deficiency was evident by other means. A Hcy within the reference interval enabled the clinician to identify those patients whose low serum vitamin level and symptoms did not reflect a tissue deficiency of B12 or folate of clinical consequence. Children with inherited disturbances of B12 metabolism, and whose serum B12 was within the reference interval, were correctly identified by an increased Hcy. A declining Hcy was evidence of correction of a deficiency even when other laboratory or clinical measurements of a response were obscured.

Adult↗
PubMed1990

A case of atelosteogenesis.

Atelosteogenesis is a rare chondrodysplasia characterised by rhizomelic short limbed dwarfism, thoracic hypoplasia, multiple joint dislocations, talipes equinovarus, and early death. The diagnosis is confirmed radiologically: short, distally tapering humeri, absent or hypoplastic fibulae, deficient vertebral ossification with coronal clefting, and anarchic ossification of phalanges are characteristic findings. We report a male child with this condition born to first cousin Bengali parents.

Adult↗
PubMed1989

The function of cellular transcobalamin II in cultured human cells.

The known function of human transcobalamin II (TC II) is to transport cobalamin (Cbl) in the circulation to tissue receptors for TC II-Cbl. Several types of human cells synthesize apo (unsaturated) TC II and the present study was conducted in order to evaluate possible functions of this endogenous TC II. The approach consisted of a correlation between the abilities of cultured cells to produce apo TC II and to internalized Cbl when presented in the free form. The amount of apo TC II produced by six lines of cultured human cells ranged from abundant to nil. The amount of free Cbl internalized by these cells correlated directly with the capacity to produce apo TC II. The interactions between endogenous TC II and free Cbl took place either at the cell surface or in the medium surrounding the cell. It was also shown that cells in culture contain free Cbl and release free Cbl into the surrounding medium. Thus it was concluded that the apo TC II produced by human cells remains intact to interact with free Cbl and to participate in the cellular metabolism of Cbl.

Carcinoma, Hepatocellular↗
PubMed1989

The nature of the defect in cobalamin G mutation.

Cobalamin G mutation (cblG) typically presents as a severe megaloblastic anemia during the first few weeks of life. The anemia responds completely to treatment with high doses of Cbl but the neurologic manifestations respond more slowly and not always completely. Cultured fibroblasts from two affected infants and virus-transformed lymphoblasts from one of the infants expressed the following: poor growth in the absence of methionine, the ability to take up and internalize Cbl bound to transcobalamin II, impaired synthesis of methionine from homocysteine, the ability to bind incoming Cbl to the respective coenzymes, but an inability to synthesize methylcobalamin in spite of a normal capacity to synthesize adenosylcobalamin. The in vitro activity of the methyltransferase dependent on methylcobalamin of cell extracts varied from low to high depending on the conditions of culture and assay. The cblG cells were unusually sensitive to the concentration of adenosylmethionine in the assay. More adenosylmethionine was required by cblG cells to achieve the same level of enzyme activity as control cells and high concentrations of adenosylmethionine did not suppress activity as in control cells. It was postulated that the defect in cblG is in the metabolism of adenosylmethionine, an essential substance for the synthesis of methionine from homocysteine.

5-Methyltetrahydrofolate-Homocysteine S-Methyltran↗
PubMed1989

[Megaloblastic anemia caused by a congenital deficiency of transcobalamin II. Apropos of a new case].

Megaloblastic anaemia is very rare in the first weeks of life and it is related to impaired metabolism of folic acid or vitamin B12. One of this disorders is the congenital transcobalamin II deficiency. The case of a three month old infant, with vomiting, diarrhoea and severe anaemia is presented. Both parents and the child had very low or undetectable levels of serum TC II, respectively. Using i.m. hydroxycobalamin at high doses, the clinical and laboratory responses have been satisfactory.

Anemia, Macrocytic↗