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Biomedical subjects

G W Dietz

Publications and source records attributed to G W Dietz.

At least 19 recordsLinked to original sources
PubMed1994

Association of dopamine D2 receptor gene haplotypes with anovulation and fecundity in female Hispanics.

Dopamine is an important neurotransmitter in the hypothalamic control of gonadotrophin secretion. Neuron response is mediated through one of five different dopamine receptors. We explored the association of D2 receptor gene polymorphisms with disorders of ovulation. We utilized a multiplex allele specific polymerase chain reaction (PCR) to detect two bi-allelic polymorphisms (four potential haplotypes) in intron 5 and exon 6 of the D2 receptor gene. A second PCR/restriction endonuclease digest was utilized to verify this. Using these assays, 185 female Hispanics (51% with known ovulatory dysfunction and 49% with normal function) were haplotyped. One allele (3) was not present in the population and there were no significant differences in remaining allele distribution between ovulatory and anovulatory patients. However, significant associations were noted between alleles and gonadotrophins and fecundity. The 4 allele had a different reproductive profile compared to the 2 allele. The 4 allele was associated with significantly higher concentrations of luteinizing hormone (LH) (means +/- SE) (19.2 +/- 2.2 versus 12.3 +/- 1.3 mIU/ml, P < 0.02) and follicle stimulating hormone (FSH) (13.2 +/- 2.0 versus 10.0 +/- 0.6 mIU/ml, P < 0.05), significantly lower concentrations of prolactin (7.9 +/- 0.8 versus 14.9 +/- 3.5 ng/ml, P < 0.02) and higher parity (1.4 +/- 0.12 versus 0.92 +/- 0.13) and lower miscarriage rates (0.89 +/- 0.1 versus 1.33 +/- 0.24, P < 0.04). We conclude that D2 receptor alleles may be associated with reproductive success through altered gonadotrophin secretion and that this effect may be independent of ovulatory function.

Adult↗
PubMed1991

Human tryptophan oxygenase localized to 4q31: possible implications for alcoholism and other behavioral disorders.

A human tryptophan oxygenase clone was isolated by screening a liver cDNA library with a rat tryptophan oxygenase cDNA clone. Analysis showed extensive homology between the rat and the human DNA and protein sequences. The combined use of cell hybrids and in situ hydridization indicated that human tryptophan oxygenase was localized to chromosome band 4q31. The tryptophan oxygenase gene may be important in some human behavior disorders, especially those associated with abnormalities of serotonin metabolism.

Alcoholism↗
PubMed1986

Segond tibial condyle fracture: lateral capsular ligament avulsion.

Avulsion fractures in the appendicular skeleton are a result of stress on a specific structure that is firmly attached to bone. A small avulsion fracture from the directly lateral surface of the lateral tibial condyle results from excessive tension on the lateral capsular ligament of the knee joint. Recognition of this fracture on an anteroposterior radiograph of a traumatized knee represents substantial evidence of major injury to the lateral joint capsule. This fracture also has a strong association with rupture of the anterior cruciate ligament. The avulsed tibial fragment is remarkably constant in site and appearance. The typical fragment is isolated by a longitudinal fracture line separating a small piece of bone from the lateral tibia. It is elliptical in outline (10 X 3 mm), with its proximal border lying 4 mm distal to the subarticular cortex of the lateral tibial condyle. A hemarthrosis of the knee joint is consistently visible.

Adolescent↗
PubMed1982

A new synaptosomal biosynthetic pathway of glutamate and GABA from ornithine and its negative feedback inhibition by GABA.

In sonicates of mouse brain synaptosomes, we demonstrated that gamma-aminobutyric acid (GABA) can be formed when L-ornithine (Orn) through L-glutamic acid (Glu), but not through putrescine (Put). Incubation of these sonicates with [3H]ORN yielded not only [3H]Glu and [3H]L-proline (Pro) but also produced [3H]GABA from the [3H]Glu. Formation of each of these three major amino acids from [3H]Orn was strongly inhibited by the addition of GABA (1-5 mM). The likely enzymatic site of this negative feedback inhibition by GABA appeared to be ornithine delta-aminotransferase (OAT). A radiometric procedure was employed to study the effects of the three amino acids cited above and of others found in the free form in brain on the activity of a 30-fold-purified OAT from rat brain. Enzyme activity was measured in the presence of low concentrations of Orn, such as might occur in vivo. OAT was inhibited by GABA to a considerably greater extent than by Glu, L-glutamine, or Put; no inhibition was found with Pro, glycine, aspartarte, taurine, or beta-alanine. The inhibition of GABA was competitive with Orn. These results clearly show that one of the molecular mechanisms underlying the negative feedback inhibition of synaptosomal GABA biosynthesis from Orn is a competitive inhibition by GABA of the brain OAT activity that is responsible for the formation of L-glutamic-gamma-semialdehyde in equilibrium with L-delta 1-pyrroline-5-carboxylic acid from Orn. Thus, the results suggest that GABA may play an important role in restricting the metabolic flow from Orn to Glu and thence to GABA. It is confirmed that L-canaline (delta-aminooxy-L-alpha-aminobutyric acid) is a potent and specific inhibitor of brain OAT whereas much weaker inhibition was observed with two other carbonyl-trapping agents, aminooxyacetic acid and hydrazine.

3-Mercaptopropionic Acid↗
PubMed1981

Initial roentgenographic manifestations of pulmonary Mycobacterium tuberculosis, M kansasii, and M intracellularis infections.

The initial radiographic features of 188 patients with pulmonary infections due to Mycobacterium tuberculosis were compared to 184 patients with M kansasii and 100 patients with M intracellularis infections. The patients were all from the University of Texas Health Center at Tyler, all had at least two positive sputum cultures and no other potential pathogen, and none had a past medical history of any type of tuberculosis. The comparison showed that all three organisms have a strong tendency to produce cavitary infiltrates in the posterior portions of the upper lobes. No distinctive or pathognomonic feature could be found. The atypical organisms were more likely to produce thin-walled cavities and far advanced unilateral disease, but both of these patterns also occurred with M tuberculosis. Endobronchial spread and volume loss were common in all three diseases. The only definite difference seems to be the absence of a primary or juvenile form of atypical tuberculosis and a much greater incidence of empyema and postprimary pleural effusions with M tuberculosis. In an individual case, the roentgenographic manifestations of the three diseases are indistinguishable.

Aged↗
PubMed1980

Purification and peptide mapping of rat brain choline acetyltransferase.

Acetyl-CoA:choline O-acetyltransferase (EC 2.3.1.6) has been purified approximately 17,000-fold from rat brain. The purification protocol included acid and NH4SO4 precipitation, followed by chromatography on CM-Sephadex, phenyl-Sepharose, Sephadex G-150, and blue dextran Sepharose. Two peaks of enzyme activity were detected after blue dextran Sepharose chromatography containing an overall yield of approximately 4% of the starting enzyme activity. The final specific activity of the blue dextran fractions was 70 to 80 mumol of acetylcholine formed min-1 mg of protein-1. Sodium dodecyl sulfate electrophoresis of the blue dextran fractions revealed three closely spaced proteins with a molecular weight of approximately 67,000. Tryptic peptide maps were prepared for each of the gel bands and indicated that they contained nearly identical primary structure.

Animals↗
PubMed1980

Injuries of the first costovertebral articulation.

The costovertebral articulations consist of two gliding type synovial joints, the costocentral and the costotransverse. When subjected to severe trauma, these joints may be subluxed or dislocated. The costotransverse joint is the more likely of the two to be injured. The first costotransverse joint is especially vulnerable because of its unique position at the top of the rib cage. Three cases are presented to show various injuries to this joint.

Adolescent↗
PubMed1979

A millipore--blue dextran affinity binding system.

Blue dextran has been adsorbed to millipore filter discs in a linkage stable under a variety of conditions. These discs have been to bind lactic dehydrogenase, which may then be specifically eluted with NADH, one of its substrates. In contrast, another enzyme, alkaline phosphatase, not expected to bind to blue dextran, was indeed completely recovered in the filtrate.

Alkaline Phosphatase↗
PubMed1979

Pulmonary manifestations of Mycobacterium intracellularis.

Pulmonary manifestations in 114 patients with at least two sputum cultures positive for M. intracellularis, no history of any kind of tuberculosis, and not other potential pathogen are described. Even with these stringent diagnostic criteria, seven patients had normal chest radiographs and another seven had reticulonodular-appearing disease without a definite focus of infection. In the other 100 patients, 92% had infiltrates in the apical and/or posterior segments of the upper lobes, and 88% had cavitary disease. The cavities were usually multiple and frequently measured over 4 cm. Scarring and volume loss were common, occurring to some degree in 70% of upper lobe foci. Pleural effusions were uncommon (5%) and usually small. Adenopathy was less common (4%) and usually occurred with upper lobe disease in younger patients. Most patients had some degree of endobronchial spread (81%). The radiographic characteristics of Mycobacterium intracellularis are not believed distinctive enought to differentiate it from Mycobacterium tuberculosis.

Aged↗
PubMed1978

Growth of Escherichia coli on glucosamine 6-phosphate: selection of a constitutive hexose phosphate transport system mutant.

Glucosamine 6-phosphate was found to be a substrate but not an inducer for the hexose phosphate transport system of Escherichia coli. Wild-type cells grow very poorly on glucosamine 6-phosphate. A mutant was selected that will grow rapidly on glucosamine 6-phosphate because it contains a constitutive hexose phosphate transport system.

Biological Transport, Active↗
PubMed1978

Buckling of the innominate artery simulating a right apical lung mass.

A tortuous retroflexed innominate artery can simulate a right apical mass. Four cases are presented to illustrate the four fairly distinct appearances which can result. When the innominate artery buckles posteriorly and laterally, it occasionally impresses deeply into the lung and becomes almost completely surrounded by air. The artery will then look like a pulmonary mass on frontal radiographs. The lower margin of the mass is always more crisply defined than the upper margin, and the appearance on the lateral film is fairly characteristic. Aortography is recommended when the radiographic picture is equivocal. In a survey of 200 randomly selected patients over 50 years old, only one had an innominate artery that presented as an apparent pulmonary mass.

Aged↗
PubMed1978

Radiographic manifestations of pulmonary Mycobacterium kansasii infections.

The radiographic characteristics of 187 pristine cases of pulmonary Mycobacterium kansasii infection are reviewed. The cases were selected from a total of 309 patients with two positive sputum cultures. All but three of the 187 patients had pulmonary disease. The progenitive focus of disease almost always involved the upper lobes, the right side (72%) more often than the left (50%). Upper lobe disease began posterior to the trachea in every case. Only one patient had disease that originated in an atypical location, that is, in the superior segment of the right lower lobe. The most frequent radiographic abnormality was cavitation (96% of diseased patients). The classical description of a thin walled cavity (or cavities) occurred in 33% of patients. A cicatricial reaction was common (two-thirds of cases). About 63% of patients had endobronchial spread. The likelihood of endobronchial disease decreased as the distance from the progenitive focus increased. Pleural effusions and adenopathy were rare. In an individual case, it is not possible to differentiate between pulmonary M. tuberculosis and M. kansasii infections.

Adolescent↗
PubMed1977

Metabolic effects of diphosphonate in primary hyperparathyroidism.

Six patients with primary hyperparathyroidism (PHPT) and one with squamous cell carcinoma of the esophagus with parathyroid hormone excess received disodium ethane-1-hydroxy-1,1-diphosphonate (EHDP) at a daily dose of 20 mg/kg orally. During treatment, the decrease in urinary calcium, total urinary hydroxyproline, and fasting urinary calcium suggested an inhibition of bone resorption. Serum calcium intestinal absorption of calcium and urinary cyclic adenosine monophosphate (cAMP) did not change significantly. This preliminary study indicates a possible role of diphosphonates in the management of inoperable cases of primary hyperparathyroidism or pseudohyperparathyroidism.

Adult↗
PubMed1977

The effect of fatigue on resident performance.

Fourteen rested and fatigued residents read a set of 25 test radiographs on two separate occasions approximately one month apart. The radiographs were made with partial chest phantom using pulmonary nodules as test objects. Seven rested and 7 fatigued residents read the radiographs, and a month later the order of fatigue was reversed. Fatigued residents had worked a minimum of 15 consecutive hours before their interpretations. Performance did not deteriorate with fatigue, and the nodule detection rate was almost identical on both occasions.

Diagnostic Errors↗
PubMed1977

Effect of kilovoltage on detectability of pulmonary nodules in a chest phantom.

A partial chest phantom was constructed to examine the effect of kilovoltage on the detectability of pulmonary nodules. Four different energies were studied: 100, 150, 200, and 300 kVp. Nodule detectability improved with increasing energies up to 200 kVp, but improvement was relatively small and was accompanied by an almost equal rise in the number of false positive readings. Patient exposures were least at 200 kVp. There seems to be no advantage in a 300 kVp technique, since nodule detectability decreased and patient exposures increased at this energy.

Humans↗
PubMed1976

The supraclavicular fossa.

The presence of a supraclavicular fossa and the visibility of its floor on chest radiographs have been ignored in the radiological literature. In a study of 500 randomly selected chest radiographs, we could identify the floor of the fossa in 29% of patients. There is extreme normal variation in the visibility, depth, and symetry of the two sides. However, the fossa can occasionally stimulate a parenchymal lung abnormality such as a fluid level or an emphysematous bleb in the upper outer lung fields.

Clavicle↗