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Biomedical subjects

G Simmons

Publications and source records attributed to G Simmons.

At least 19 recordsLinked to original sources
PubMed1996

The increasing prevalence of obesity in New Zealand: is it related to recent trends in smoking and physical activity?

AIMS: To describe recent trends in body mass in Auckland, and to determine whether associated changes in cigarette smoking and physical activity could explain these trends. METHODS: Risk factors for coronary heart disease were measured in three age-stratified random samples of Europeans aged 35-64 years using a standard protocol in 1982, 1986-8 and 1993-4. Body mass index (BMI) was calculated as weight in kg/(height in m2), with overweight or obese being defined as BMI>25. Results. The age-standardised mean BMI increased from 26.6 (25.4-25.8) to 26.4 (26.2-26.7) in men and from 24.6 (24.2-24.9) to 25.1 (24.8-25.5) in women between 1982 and 1993-4. The prevalence of overweight and obese people increased from 52.8% (48.1-57.7) to 64.2% (58.1-70.3) in men and from 36.5% (31.5-41.5) to 44.9% (39.7-50.1) in women. Self reported cigarette smoking declined between 1982 and 1993-94 with an associated increase in the prevalence of ex-smokers. The change in smoking status accounted for only 7% and 10% of the observed increase in BMI in men and women respectively. Most of the observed change in BMI was due to a general increase in BMI in all smoking categories in both sexes. The prevalence o leisure time physical activity increased in both sexes between 1986-88 and 1993-94 while work physical activity decreased. The change in physical activity should have decreased mean BMI by approximately 4% in men and 14% in women. As with smoking there was a trend towards increasing mean BMI irrespective of the activity undertaken. CONCLUSION: Recent trends in smoking cessation explain only a small percentage of the increase in body mass while the trends in physical activity would have predicted a small decrease in the prevalence of obesity, contrary to the observed trends. By exclusion, an increase in total energy intake, is the most likely explanation for the observed trends.

Adult↗
PubMed1995

Cell-to-cell fusion, but not virus entry in macrophages by T-cell line tropic HIV-1 strains: a V3 loop-determined restriction.

T-cell lines chronically infected with laboratory adapted, T-cell tropic HIV-1 strains (RF, LAI, CBL-4, and NY5) induced syncytia after cocultivation with primary macrophages. Such fusion-competent strains, however, replicated inefficiently after cell-free infection of macrophage cultures. Evidence based on proviral DNA synthesis, pseudotype penetration, and a V3 loop mutation revealed that cell-free infection was restricted at a prepenetration stage in entry and controlled by envelope sequences. Our results suggest that primary macrophages are sensitive to cell-to-cell but not to virion-to-cell fusion induced by the envelope glycoproteins of several T-cell tropic HIV-1 strains.

Cell Communication↗
PubMed1994

Comparison of placement of the laryngeal mask airway with endotracheal tube by paramedics and respiratory therapists.

STUDY OBJECTIVE: To determine the learning curve of nonphysician emergency personnel on placement of the laryngeal mask airway as compared to performance of endotracheal intubation. DESIGN: Prospective, comparative, randomized, patient-blinded trial. SETTING: Regional hospital operating room. PARTICIPANTS: Seven experienced paramedics and 12 respiratory therapists trained in endotracheal intubation. INTERVENTIONS: Patients used as subjects were anesthetized and paralyzed. Each participant then performed placement of both the laryngeal mask airway and endotracheal tube on the same patient in random sequence. Both techniques were observed for speed, difficulty, and effectiveness. MEASUREMENTS AND MAIN RESULTS: The techniques were timed from the point at which the participant touched the patient to the time they were able to effectively ventilate the patient. Participants also were asked to rate the difficulty of each technique on a 100-mm visual analog score. Failure (three attempts without successful ventilation) rates also were monitored. The mean time to ventilate successfully with the laryngeal mask airway was significantly less than that with the endotracheal tube (38.9 +/- 1.9 seconds versus 206.1 +/- 31.9 seconds, P < .0001). The average number of attempts was 1.0 +/- 0.0 for the laryngeal mask airway and 2.22 +/- 0.21 for the endotracheal tube (P < .01). No one failed to place the laryngeal mask airway; and ten of 19 (52.6%, P < .01) failed to perform endotracheal intubation. The endotracheal tube had a significantly higher rating of difficulty than did the laryngeal mask airway (67.3 versus 8.64, P < .0001).

Allied Health Personnel↗
PubMed1993

Is CD4 sufficient for HIV entry? Cell surface molecules involved in HIV infection.

HIV-1, HIV-2 and SIV each bind to CD4 as the first step in virus entry. However, alternative receptors may also be used. HIV-1 binds to glycolipids with terminal galactosylceramide residues on neural cells; opsonized virus binds to Fc receptors; HIV-2 can infect certain CD4-negative cells. Further receptors may also play a role in CD4-mediated infection, including cell adhesion molecules and possibly cell surface proteinases. After binding to CD4, immunodeficiency viruses require secondary molecules to effect fusion between the virus envelope and the cell membrane; these accessory requirements differ between HIV-1, HIV-2 and SIV.

Animals↗
PubMed1993

[123I]HIPDM pulmonary imaging demonstrates elastase-induced pulmonary emphysema.

Because more than 90 percent of [123I]hydroxyiodobenzyl-propanediamine (HIPDM) is localized in the lung after intravenous injection, the radiopharmaceutical has been proposed as a lung imaging agent. Its potential usefulness for the detection of pulmonary emphysema was evaluated in an animal model of elastase-induced emphysema along with [99mTc]MAA lung perfusion imaging. To induce lung emphysema, Long-Evans rats (200-250 g) were given 400 IU/Kg elastase intratracheally under ether anesthesia. Four weeks after elastase treatment, 15 treated and 15 nontreated rats were paired and simultaneously imaged under a scintillation camera immediately following intravenous injection of 0.25-0.3 mCi[99mTc]MAA. The procedure was repeated 48 hr later using 0.25-0.3 mCi[123I]HIPDM. Activity in the region of interest (ROI) over the lungs was recorded after the injections. Total counts per ROI from each rat were measured and normalized by lung volume. The normalized lung activity ratio of treated/nontreated rats was computed. The mean ratios of HIPDM and MAA were 0.847 and 0.802, respectively. The significant decrease in uptake of both HIPDM (p < 0.021) and of MAA (p < 0.025) in the elastase-treated lungs indicates decrease in functioning vascular endothelium and decrease in number of pulmonary capillary vessels, respectively, reflecting damage in capillaries and small arterioles. The decrease in treated/nontreated ratios lung is consistent with a significant alteration in pulmonary function and a significant increase in mean linear intercept (p < 0.005) in treated lung. Since the imaging reflects pulmonary endothelial receptor function, [123I]HIPDM lung imaging may serve as an alternative diagnostic modality for pulmonary emphysema.

Animals↗
PubMed1991

The institutionalization of operations research.

When the conceptualization of OR is inappropriate, institutionalization will not take place. For this reason, the discussion here has focused as much on the pitfalls in OR design as on factors that facilitate institutionalization. Research that is inappropriately adapted to the societal or programmatic context will not be institutionalized, nor will OR lead to institutionalized research capabilities if theory is ignored or the research lacks credibility. The institutionalization of credible and scientifically sound OR requires well-trained social scientists who can carry out this task. Career opportunities must persist in OR so that well-trained scientists will find in an attractive and rewarding pursuit. Long-term projects facilitate institutionalization by providing a setting where work teams can be developed and career tracks defined. Academics and universities institutionalize OR by sponsoring training in applied research and developing high-level research leadership. For this reason, institutional linkages and mechanisms that nurture collaboration facilitate the institutionalization of OR. Finally, institutionalization of OR implies that research is being utilized for action by program management and the policy community. There is extensive literature on the determinants of research utilization, much of which is relevant to the question of how OR can be institutionalized.

Academies and Institutes↗
PubMed1990

I-123 hydroxyiodobenzyl propanediamine (HIPDM) cerebral blood flow imaging demonstrating transtentorial diaschisis.

To assess the clinical significance of transtentorial diaschisis (TTD) as demonstrated by I-123 HIPDM brain imaging, SPECT and/or planar images of 35 patients with stroke, 26 patients with Alzheimer's disease (AD), 2 patients with Creutzfeldt-Jakob disease (CJD), and 1 patient with a schizoaffective disorder were analyzed. TTD was observed in 21 of the 35 patients with strokes. In 13 stroke patients, TTD was associated with large infarcts in the middle cerebral artery (MCA) territory; in the remaining 8 stroke patients, TTD was associated with internal capsule and/or basal ganglia infarcts. TTD was not associated with small occipital or parietal infarcts. Despite cortical perfusion decrements, TTD was not seen in the AD patients, the CJD patients, or the patient with schizoaffective disorder. It is concluded that 1) TTD frequently occurs following cerebral infarct of the MCA territory (60% of the patients in this sample); 2) absence of TTD in the presence of a large cerebral perfusion abnormality may represent neuronal dysfunction of the cerebral cortex; and 3) the presence of TTD without a significant cortical perfusion abnormality may indicate basal ganglia and/or internal capsule infarct.

Alzheimer Disease↗
PubMed1986

Thrombin-like enzyme from the venom of Bitis gabonica. Purification, properties, and coagulant actions.

Gabonase, an enzyme which acts on fibrinogen and factor XIII in uniquely thrombin-like ways, was purified to electrophoretic homogeneity from the venom of Bitis gabonica. On sodium dodecyl sulfate-polyacrylamide electrophoresis, the reduced protein behaved as a single chain with Mr = 30,600. The enzyme contains 20.6% carbohydrate, no free sulfhydryl groups and hence, from amino acid analysis, five disulfide bonds. Its extinction coefficient (E1%1cm) at 280 nm is 9.6. Its pI is 5.3. Gabonase has an active serine residue, is inactivated by phenylmethanesulfonyl fluoride, and has an active histidine which reacts with the chloromethyl ketone of tosyl-L-lysine. Its NH2-terminal amino acid sequence (Val-Val-Gly-Gly-Ala-Glu-Cys-Lys-Ile-Asp-Gly-His-Arg-Cys-Leu-Ala-Leu-Leu -Tyr-) is homologous to the B chain of thrombin. The activity of the enzyme is stabilized by calcium ion. It exhibits strong N alpha-p-tosyl-L-arginine methyl esterase activity, hydrolyzes tripeptide nitroanilide derivatives weakly or not at all, and cleaves no peptide bonds in insulin, glucagon, or the S peptide of ribonuclease. Gabonase clots fibrinogen with a specific activity of 45 NIH thrombin-equivalent units/mg, releasing both fibrinopeptides A and B and showing substrate inhibition at fibrinogen concentrations of 3 mg/ml or greater. The enzyme also activates factor XIII. It is not inactivated by either heparin or hirudin.

Amino Acid Sequence↗
PubMed1985

Action of crotalase, an enzyme with thrombin-like and kallikrein-like specificities, on tripeptide nitroanilide derivatives.

Since crotalase has thrombin-like and kallikrein-like functional and structural properties, we compared the actions of crotalase, thrombin and plasma kallikrein on 13 tripeptide nitroanilide substrates. Initial rates of hydrolysis were determined at 27 degrees C, pH 8.3, and used to construct Lineweaver-Burk plots from which Km and Vmax were determined. The ratio of kcat/Km was taken as a measure of enzymatic specificity. Crotalase yielded kcat/Km values for the following nitroanilide substrates in descending order of magnitude: H-D-NLeu-CHA-Arg, H-D-Pro-HHT-Arg, Tos-Gly-Pro-Arg, H-D-PhGly-Phe-Arg, Cbo-Glu(BuO)-Gly-Arg, H-D-But-CHA-Lys, H-D-CHG-But-Arg, H-D-NLeu-HHT-Lys, H-D-HHT-Ala-Arg, Bz-Pro-Phe-Arg, Tos-Gly-Pro-Lys, MeS-Leu-Gly-Arg, MeO-CO-CHG-Gly-Arg. This pattern of specificity correlated only roughly with those of thrombin and kallikrein.

Chromogenic Compounds↗
PubMed1980

Radioimmunodetection of cancer with radiolabeled antibodies to alpha-fetoprotein.

Sixteen patients with histologically proven malignant neoplasia were investigated by radioimmunodetection, using goat anti-alpha-fetoprotein (AFP) antibody radiolabeled with 131I. Images of the chest and abdomen were made with a scintillation camera, usually at 24 and 48 hr following injection of 1 to 2.5 mCi of radioiodinated antibody. Computer-assisted processing for the subtraction of 99mTc background radioactivity was used to enhance the detection and localization of tumors visualized by immune scintigraphy. All 12 sites involved by five AFP-producing tumors could be demonstrated by radioimmunodetection, while normal goat immunoglobulin G labeled with 131I failed to show similar results in one of the patients in whom the radioactive AFP antibody achieved tumor radiolocalization. Five patients in whom the tumors were not expected to produce AFP also had their large tumors demonstrated by immune scintigraphy in 6 of 16 tumor sites. The average tumor to non-tumor 131I image count density ratios were 3.20 and 1.96 for the AFP-containing and putatively AFP-deficient tumors, respectively. The image contrast was significantly greater for the AFP-containing tumors, and the subtraction technique enhanced the image contrast more than 2-fold. Based upon these initial results, the sensitivity of the method (true-positive rate) was 100%, its specificity (true-negative rate) was 80%, and the accuracy of the technique was 85%. This study thus indicates that radioimmunodetection of cancer with radioactive AFP antibodies can be useful in the evaluation of patients with AFP-containing neoplasms.

Adult↗
PubMed1980

Differential accumulation of Tc-99m DTPA and Tc-99m pyrophosphate within cerebral and cranial lesions: concise communication.

We sought to determine the clinical utility of using a bone-scanning agent in addition to a brain-scanning agent for the imaging of cerebral and cranial lesions. Images were obtained in 51 patients with Tc-99m diethylene-triamine-pentacetic-acid (DTPA) followed by Tc-99m pyrophosphate (PPi) within 2--5 days. The scans were qualitatively analyzed and the lesion-to-background count density ratios were determined from the corresponding brain and skull images. Only four of 20 cerebral infarctions were better demonstrated with PPi, whereas they were better with DTPA in 14 patients. They were equally good in two patients. The average lesion-to-background count-density ratio for infarction was 1.555 +/- 0.335 with DTPA and 1.428 +/- 0.573 with PPi (p < 0.05). Primary brain tumors were better visualized with DTPA in four out of five cases (p < 0.05). Metastases to brain showed up better with DTPA in 15 of 16 patients (p < 0.05), whereas all ten metastases to skull were seen better with PPi (p < 0.01). These results support previous reports regarding the radiopharmaceutical of choice for tumor imaging but not for infarction. This may be due to the differences in blood clearance for the various imaging agents.

Brain Neoplasms↗
PubMed1980

Imaging approach in radioimmunodetection.

External in vivo imaging of tumors with radioactively labeled antibodies to tumor-associated antigens requires processing to remove interfering nontarget radioactivity. Processing entails the use of simulated nontarget compounds labeled with a radionuclide physically different from that on the antibody and substraction of the simulated nontarget activity from the nontargeted antibody. A 2-fold increase of the target to nontarget radioactivity is achieved that has made possible a greater than 70% tumor detection rate.

Antibodies, Neoplasm↗
PubMed1977

Experimental hyphema clearance in rabbits. Drug trials with 1% atropine and 2% and 4% pilocarpine.

The effect of topical 1% atropine sulfate, 2% pilocarpine hydrochloride, and 4% pilocarpine hydrochloride on the clearance rate of RBCs labeled with chromium 51 (51Cr) that were injected into the anterior chamber of rabbits was determined by monitoring sequential radioactivity counts. Counts were made directly over the anterior chamber. One eye of each animal was treated with either 1% atropine, 2% pilocarpine, or 4% pilocarpine, and the other eye served as a control. None of these drugs significantly altered the clearance rate of 51Cr-labeled RBCs injected into the anterior chamber.

Animals↗
PubMed1976

The dilemma of family planning in a North Indian State.

An empirical study of the family planning program and its clients in the rural areas of Allahabad Division of Uttar Pradesh in India was undertaken in 1971-1972. While family planning acceptance in this region is low, interviews with villagers and family planning staff suggest that organizational shortcomings of the program may help to explain the low level of acceptance. The reported level of contact between the program field staff and the village population was unexpectedly low. The paper discusses a number of administrative problems within the family planning organization, especially at the level of the primary health center. It is concluded that in designing family planning programs, efforts should be made to minimize organizational requirements.

Family Characteristics↗