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Biomedical subjects

R Hubbard

Publications and source records attributed to R Hubbard.

At least 91 records · Page 5Linked to original sources
PubMed1992

High resolution crystal structures and comparisons of T-state deoxyhaemoglobin and two liganded T-state haemoglobins: T(alpha-oxy)haemoglobin and T(met)haemoglobin.

The origin of co-operativity in haemoglobin (Hb) resides in the reduced affinity of the T-state. T-state Hb crystals grown from polyethyleneglycol can be liganded without the molecule switching to the R high affinity state. X-ray analysis of T-state alpha-oxy Hb and T-state met Hb has identified the structural basis for reduced affinity. The nature of the chemical tension at the haem environment is different in the alpha and beta haems. There are small but definite structural changes associated with ligation in the T-state: these prove to be mostly in the same direction as the larger changes that occur in the T-->R transition.

Computer Simulation↗
PubMed1992

Structural biology and diabetes mellitus: molecular pathogenesis and rational drug design.

Emerging concepts in the aetiology and pathogenesis of Type 1 (insulin-dependent) diabetes mellitus may offer new opportunities for treatment and cure. Here we describe recent advances in structural molecular biology and molecular design relevant to rational drug discovery. Such approaches focus on the three-dimensional structures of macromolecules and their interactions. In the coming decade such techniques may be applied to a wide variety of diabetes-related targets.

Amino Acid Sequence↗
PubMed1992

The 10-year experience of an academically affiliated occupational and environmental medicine clinic.

Occupational and environmental diseases are underrecognized. Among the barriers to the successful diagnosis, treatment, and prevention of these conditions are inadequate consultative and information resources. We describe the 10-year clinical and training experiences of an academically affiliated referral center that has as its primary goal the identification of work-related and other environmental diseases. The University of Washington Occupational and Environmental Medicine Program has evaluated 6,048 patients in its diagnostic and screening clinics. Among the 2,841 seen in the diagnostic clinics, 1,553 (55%) had a work-related condition. The most prevalent diagnoses included asbestos-related lung disease (n = 603), toxic encephalopathy (n = 160), asthma (n = 119), other specific respiratory conditions (n = 197), carpal tunnel syndrome (n = 86), and dermatitis (n = 82). The clinics serve as a training site for fellows in the specialty training program, primary care internal medicine residents, residents from other medical specialties, and students in industrial hygiene, toxicology, and occupational health nursing. The program serves two additional important functions: providing consultative services to community physicians and training specialists and other physicians in this underserved area of medicine.

Adolescent↗
PubMed1991

Human neutrophils express the alpha 1-antitrypsin gene and produce alpha 1-antitrypsin.

The potent serine protease, neutrophil elastase (NE), is stored in neutrophil azurophilic granules, where it is available to degrade phagocytosed material and can be released by the cell to assist in tissue migration and help clear tissue debris. While neutrophils carry NE, they cannot produce it; the NE gene is expressed only in bone marrow granulocyte precursor cells. Protection of normal tissues from the destructive capacity of NE is provided by alpha 1-antitrypsin (alpha 1 AT), a 52-Kd serine antiprotease produced by hepatocytes and mononuclear phagocytes. In the context of the broad destructive capacity of NE, we evaluated the concept that human neutrophils may be able to modulate the extracellular activity of NE by synthesizing and secreting alpha 1AT. Immunocytochemical analysis demonstrated that the neutrophil contains alpha 1AT. Northern analysis and in situ hybridization with alpha 1AT-specific probes demonstrated the presence of alpha 1AT messenger RNA transcripts within neutrophils. [35S]methionine-labeling of neutrophils followed by immunoprecipitation of the supernatant with an anti-alpha 1AT antibody and sodium dodecyl sulfate-acrylamide gel analysis demonstrated that neutrophils can synthesize alpha 1AT de novo and secrete the synthesized molecule. In the presence of major neutrophil degranulation, the antiprotease effect of neutrophil alpha 1AT is overwhelmed, allowing the NE to act unopposed in the extracellular microenvironment. However, in conditions where small amounts of NE are released by neutrophils, at least some of the secreted newly synthesized alpha 1AT was capable of complexing with NE. Thus, despite the fact that the neutrophil cannot synthesize NE, it can synthesize and secrete alpha 1AT, the inhibitor of NE, ie, the neutrophil is capable, to some extent, of modulating NE activity in the local milieu without the help of antiproteases produced by other cells.

Gene Expression↗
PubMed1990

Atropine: effects on glucose metabolism.

We have employed the primed constant infusion technique to investigate the metabolic effects of the organophosphate antidote, atropine, on glucose homeostasis in rats. This method utilizes the radioisotopes 6-3H-glucose to measure production and uptake and U-14C-glucose to measure oxidation. Our data indicate that glucose production significantly (p less than 0.05) increased (24.0 +/- 2.0 vs. 30.9 +/- 2.6 mumoles.kg-1.min-1) following atropine administration. The elevated rate of glucose turnover was associated with concomitant increases in glucose oxidation (8.3 +/- 0.6 vs. 12.0 +/- 0.8, mumoles.kg-1.min-1), the percent of glucose uptake oxidized (37.2 +/- 2.0 vs. 44.6 +/- 2.6), and the percent carbon dioxide produced from glucose (8.4 +/- 0.7 vs. 12.0 +/- 1.8). Presumably, these glucokinetic changes were mediated by elevated plasma catecholamines (Epi: 166 +/- 19 vs. 271 +/- 50 pg/ml; Norepi: 262 +/- 24 vs. 525 +/- 63 pg/ml, p less than 0.05) since other glucoregulatory hormones (insulin, glucagon, and corticosterone) were not significantly affected by atropine administration. In addition, there was no change in VO2 associated with atropine administration. These data indicate that atropine enhances glucose production and utilization; such effects could be ergogenic during exercise in thermoneutral conditions.

Animals↗
PubMed1989

Effect of dietary protein on serum insulin and glucagon levels in hyper- and normocholesterolemic men.

This study was designed to test the effect of dietary protein on blood levels of insulin and glucagon. Twelve normocholesterolemic (less than 200 mg/dl) and 11 hypercholesterolemic greater than 240 mg/dl) healthy male subjects, 31-62 years of age, were randomly given 3 liquid test meals 1 week apart. Meals were identical except for the protein source (soybean, casein, or protein free). Blood was drawn at fasting, and 0.5 and 2 h postprandially. Insulin and glucagon levels were measured by radioimmunoassay. Hypercholesterolemic subjects had a higher (P less than 0.05) insulin/glucagon ratio (1.5) than normocholesterolemic subjects (0.7) 2 h post-prandially when fed the casein test meal. There was no significant difference following the soybean test meal. This implies that the post-prandial insulin/glucagon ratio was affected by the amino acid composition of the diet. There was a consistently higher insulin response to all test meals among hyper- versus normocholesterolemic subjects. These results are consistent with our hypothesis that the hypocholesterolemic effects of soybean protein and the hypercholesterolemic effects of casein were mediated by altered levels of insulin and glucagon.

Adult↗
PubMed1988

Cholesterolemic effects of the lysine/arginine ratio in rabbits after initial early growth.

The lysine/arginine ratio has been directly associated with serum cholesterol levels. Male, New Zealand rabbits with a mean weight of 2.1 kg were fed, ad libitum, one of three diets containing 14% vegetable oil and 20% protein from casein, soy or almonds with lysine/arginine ratios of 2.2, 0.9, or 0.3, respectively. At the end of three weeks for phase 1, the serum cholesterol level of the casein group (154 +/- 25 mg/dl, mean +/- SD) was twice the level and significantly greater (p less than 0.02) than either of the plant protein groups (soy 70 +/- 7, almond 78 +/- 6 mg/dl). During phase 2, the almond diet was supplemented with L-lysine to increase the lysine/arginine ratio from 0.3 to 3.0 while casein remained as the high, and soy the low lysine/arginine ratio control diets. Serum cholesterol levels remained high for the casein, and low for the soy groups, while lysine supplementation significantly increased (p less than 0.05) the serum cholesterol level in the almond protein group (from 78 +/- 6 to 101 +/- 10), but not greater than the casein group. Growth was similar for rabbits fed soy or casein diets throughout the study, but lower (p less than 0.02) for the almond group. Thus, growth rate was not related to the effect of dietary protein on levels of serum cholesterol. While there is a direct relationship between hypercholesterolemia and the absolute amount of dietary lysine and with the lysine/arginine ratio, the data suggest that this is only a partial explanation for the effect of proteins on the control of serum cholesterol levels.

Animals↗
PubMed1987

Monoclonal antibodies to human parathyroid hormone (1-34) and their use in the immunocytochemical detection of parathyroid tumours.

Monoclonal antibodies against the biologically active N-terminal fragment of human parathyroid hormone, hPTH (1-34), were produced. The procedure included the use of novel secondary immunization in vitro of mouse spleen cell cultures. Dissociated spleen cells from primary immunized Balb/c mice, were cultured for five days in the presence of thymocyte conditioned media (TCM) and synthetic hPTH (1-34). Contrary to previous findings by other workers, in our hands Balb/c mice responded well. Following immunization the spleen cells were fused with NSl myeloma cells and cultured for eleven days before screening for antibody. Using an enzyme linked immunosorbent assay (ELISA) a number of positive clones were detected. Positive cells were cloned by limiting dilution and fifteen specific monoclonal hybridomas were produced. The immunoglobulin class of the different monoclonal antibodies was found to be IgGl. The immunocytochemical reaction was tested with chief cell carcinoma tissue and found to be clearly positive.

Animals↗
PubMed1987

Augmentation of lung antineutrophil elastase capacity with recombinant human alpha-1-antitrypsin.

To evaluate the potential use of recombinant DNA-produced alpha-1-antitrypsin (alpha-1-AT) to augment the lung antineutrophil elastase defenses in alpha-1-AT deficiency, we compared the kinetics of intravenously administered recombinant produced alpha-1-AT (r alpha-1-AT) and purified normal human plasma alpha-1-AT (p alpha-1-AT) in the blood and lung of rhesus monkeys. The r alpha-1-AT was produced in yeast transformed with an expressing plasmid containing a full-length human alpha-1-AT complementary deoxyribonucleic acid and purified to greater than 99% homogeneity. The r alpha-1-AT has a molecular weight of 45,000, no carbohydrates, and is identical in sequence to normal plasma alpha-1-AT except for an additional N-terminal acetylmethionine. Despite its lack of carbohydrates, the r alpha-1-AT inhibited human neutrophil elastase with an association rate constant similar to that of p alpha-1-AT. Rhesus monkeys were infused intravenously with 120 mg/kg of r alpha-1-AT (n = 13) or p alpha-1-AT (n = 12) and the serum, urine, and lung epithelial lining fluid (ELF) concentrations of these molecules quantified at various intervals.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Eugenics: new tools, old ideas.

Prejudices against people who have noticeable disabilities have resulted in needless social and economic barriers to their participation in society. In Germany under the Nazis, a movement for eugenics, or "racial hygiene," led to the sterilization and, later, the elimination of people with particular mental or physical disabilities. In the United States, earlier in the century, the eugenics movement produced compulsory sterilization laws. At present, physicians and scientists are developing techniques for prenatal diagnosis of increasing numbers of inherited diseases and disabilities, although more babies and children are needlessly disabled because of poverty and accidents than for genetic reasons. Such prenatal tests are being hailed as progress, yet their availability is once again turning pregnancy into a medical event and confronts women with decisions and choices that can be extremely difficult.

Attitude to Health↗
PubMed1986

Oral pyridostigmine administration in rats: effects on thermoregulation, clinical chemistry, and performance in the heat.

We have recently reported that acute intraperitoneal administration of pyridostigmine bromide to rats resulted in significant decrements in physical performance in the heat, adverse thermoregulatory effects, and exacerbated elevations in several indices of heat/exercise injury. Since it will be consumed orally as a prophylaxis for organophosphate poisoning, pyridostigmine was dissolved in the drinking water of rats. Consumption of pyridostigmine for 7 days (n = 34, 6.6 mg/day) resulted in a 23% (p less than 0.001) reduction of circulating cholinesterase when compared with a control group (n = 31) while ingestion for 14 days (n = 35, 8.9 mg/day) elicited a 39% (p less than 0.001) inhibition of circulating cholinesterase when compared to a second control group (n = 33). Water and food consumption, rate of weight gain, and overt behavior were unaffected by pyridostigmine consumption. When approximately half the animals in each group were exercised (9.14 m/min) in the heat (35 degrees C) to hyperthermic exhaustion (Tre = 42.5-43 degrees C, rats unable to right themselves), pyridostigmine consumption for 14 days effected a significantly (p less than 0.05) increased rate of weight loss, but no further effects on thermoregulation or performance were noted. Several minor increments were observed in clinical indices of heat/exercise injury in rats consuming pyridostigmine for 14 days. These data indicate that oral dosages of pyridostigmine can probably be titrated to levels of cholinesterase inhibition which are efficacious in prophylaxis against organophosphate toxicity without significant effects on selected physiologic and metabolic processes.

Administration, Oral↗
PubMed1986

Eugenics and prenatal testing.

Prejudices against people with disabilities, poor people, and immigrants during the nineteenth century generated a science of "race improvement" called eugenics. In the United States, a number of eugenic measures were enacted early in this century, but it was in Nazi Germany that eugenics flourished under the name of racial hygiene (Rassenhygiene). In the guise of furthering the health of the German people, German scientists and physicians initially designed programs of sterilization. Next came euthanasia and finally mass extermination of "lives not worth living." Remembering this history, many German women oppose the new technical developments in prenatal diagnosis because they see them as yet another way to specify what kinds of people are and are not fit to inhabit the world. This paper tries to place the new technologies in the context of eugenics and to point out some of the ways in which the new, supposedly liberating, choices in fact limit women's control over our lives.

Abortion, Induced↗
PubMed1985

Genetic screening of prospective parents and of workers: some scientific and social issues.

Genetic screening programs are based on assumptions and values that reflect the history of racial and social eugenics in the United States and Europe. They stigmatize individuals by shifting the focus from social, economic, and political decisions that affect the health of prospective parents, newborns, and workers to "bad genes," that is, intrapersonal factors that are given the status of "causes" of disease. Prenatal screening, at best, can help the relatively few individuals who know that their future children are at risk for a particular inherited disease or disability; it has little positive value for the average person. Workplace genetic screening has not been shown to reduce occupational disease, but it has led to employment discrimination and has drawn attention away from controlling exposures to toxic chemicals in the workplace.

Amniocentesis↗
PubMed1985

Production and growth of hybridomas secreting monoclonal antibodies to human thyroid stimulating hormone.

Female Balb/c mice were immunized with human thyroid stimulating hormone (hTSH). The spleen cells of responding mice were used in a cell fusion with NS1 mouse myeloma cells to define 27 stable anti-hTSH hybridomas. The antibody-secreting cell lines, designated SY/T8/1-6, were characterized and three were found to be completely specific for h-TSH while the other three showed some cross reactivity with LH and hCG. Six of the monoclonal antibodies have been well characterized and their parent hybridomas isolated and banked at -196 degrees C for future studies. The hybridomas have been raised from liquid nitrogen and recultured in RPMI 1640 medium. Progress is being made in the investigation of the growth characteristics of these hybridoma cell lines.

Animals↗
PubMed1985

The effects of econazole on the growth of murine myeloma cells and its use in hybridoma production.

The effect of econazole, an antifungal agent, on the stability of NS1/Ag4 myeloma cells in culture was investigated with the view to its use in the control of fungal contamination in lymphocyte hybridoma monoclonal antibody production. The recommended dose of 1 microgram/ml was found to reduce cell numbers, viability and survival, and to effect dramatic dose related changes in DNA synthesis in the NS1 myeloma line and hence econazole is not suitable as an added antifungal agent in monoclonal antibody production using NS1 cells and their derived hybridomas.

Animals↗