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Biomedical subjects

D Bell

Publications and source records attributed to D Bell.

At least 217 records · Page 12Linked to original sources
PubMed1980

Inhibition of photosynthetic electron transport in isolated spinach chloroplasts by two 1,3,4-thiadiazolyl derivatives.

Buthidazole (3-[5-(1,1-dimethylethyl)-1,3,4-thiadiazol-2-yl]-4-hydroxy-1-methyl-2-imidazolidinone) and tebuthiuron (N-[5-(1,1-dimethylethyl)-1,3,4-thiadiazol-2-yl]-N,N'-dimethylurea) are two new promising herbicides for selective weed control in corn (Zea mays L.) and sugarcane (Saccharum officinarum L.), respectively. The effects of these two compounds on various photochemical reactions of isolated spinach (Spinacia oleracea L.) chloroplasts were studied at concentrations of 0, 0.05, 0.5, 5, and 500 micromolar. Buthidazole and tebuthiuron at concentrations higher than 0.5 micromolar inhibited uncoupled electron transport from water to ferricyanide or to methyl viologen very strongly. Photosystem II-mediated transfer of electrons from water to oxidized diamonodurene, with 2,5-dibromo-3-methyl-6-isopropyl-p-benzoquinone (DBMIB) blocking photosystem I, was inhibited 34 and 37% by buthidazole and tebuthiuron, respectively, at 0.05 micromolar. Inhibition of photosystem I-mediated transfer of electrons from diaminodurene to methyl viologen with 3,4-dichlorophenyl-1,1-dimethylurea (DCMU) blocking photosystem II was insignificant with either herbicide at all concentrations tested. Transfer of electrons from catechol to methyl viologen in hydroxylamine-washed chloroplasts was inhibited 50 and 47% by buthidazole and tebuthiuron, respectively, at 0.5 micromolar. The data indicate that the inhibition of electron transport by both herbicides is primarily at the reducing side of photosystem II. However, since catechol is an electron donor at the oxidizing side of photosystem II, between water and chlorophyll a(680), and lower inhibition levels were observed in the last study (catechol to methyl viologen), it may be that there is also a small inhibition of the mechanism of water oxidation by both herbicides.

Journal Article↗
PubMed1979

Development of a closed-loop artificial pancreas.

A closed-loop glucose controlled insulin infusion system was developed, consisting of elements for continuous blood glucose analysis, a computer control system, and infusion systems. Improvements include decreased size, cost reduction and better performance. The algorithm used was a piecewise linear representation of the sigmoidal curve commonly employed. The apparatus has been applied to simulation of the healthy beta cell and glucose clamp studies.

Artificial Organs↗
PubMed1979

Emergency room utilization in the first 15 months of life: a randomized study.

The impact of a system of primary pediatric care on emergency room use in a municipal hospital was measured by comparing that use in two randomly selected populations. The population that was offered participation in a primary care program consistently used the emergency room less than did the control group. Analysis of the pattern of utilization revealed that the differences were limited to patients who actually participated in the program, and to weekday use of the emergency room. Unusually heavy (greater than ten visits per year) use of the emergency room was virtually eliminated among participants in the primary care program.

Emergency Service, Hospital↗
PubMed1977

Autoregulation of nephron filtration rate in the dog assessed by indicator-dilution technique.

Micropuncture studies were conducted in anesthetized dogs to evaluate single nephron glomerular filtrate rate (SNGFR) and SNGFR autoregulation when assessed by means of an indicator-dilution technique (SNGFRID), which does not require interruption of distal volume delivery. In 18 dogs, control renal arterial pressure was 124 +/- 11 mmHg (SD), renal blood flow (RBF) was 185 +/- 58 ml/min, and whole kidney GRF was 37 +/- 7 ml/min. SNGFRID averaged 57 +/- 15 nl/min and was significantly lower than SNGFR determined on the basis of total collections (SNGFRTC) from proximal tubules (75 +/- 17 nl/min). However, SNGFRID was not significantly different from the overall average SNGFR of 62 +/- 12 nl/min estimated from whole kidney GFR and the total number of glomeruli (613,000 +/- 74,000). In 10 animals, renal arterial pressure was reduced to an average of 94 +/- 8 mmHg; whole kidney autoregulation was highly efficient and average RBF and GRF remained within 1 and 3% of their control values. Likewise, SNGFRID was not significantly altered at 52 +/- 17 and 52 +/- 16 nl/min. In contrast, SNGFRTC decreased significantly from 72 +/- 17 to 51 +/- 13 nl/min. These results indicate that the indicator-dilution technique provides a reliable assessment of SNGFR and allows the manifestation of single nephron autoregulatory behavior. They provide further support for the hypothesis that maintenance of distal volume delivery may be a necessary aspect of the autoregulation phenomenon.

Animals↗
PubMed1976

Urinary tract changes in obstetric vesico-vaginal fistulae: a report of 216 cases studied by intravenous urography.

Intravenous urographies carried out routinely on 216 cases of vesico-vaginal fistulae were reviewed. All the patients had suffered from urinary incontinence following obstructed labour for periods varying from immediate post-partum period to as long as 35 years with the majority (48%) presenting in the first year of the disease. One hundred and eleven patients (51-4%) showed no urinary tract abnormality. Calyceal abnormality was graded from 1-5 in ascending order of severity. The most frequent abnormality was Grade 1 (or minimal calyceal blunting) found in 75 (71%) of 105 cases showing lesions. Ten patients had non-functioning kidneys. There was no correlation of severity of calyceal grading with duration of the disease. Other notable changes were hydroureter in 75 (34%), medial deviation of the terminal ureters in 21 (9-7%) and bladder calculi in four. The study reveals a high risk of morbidity to the kidneys in patients with vesico-vaginal fistulae and the predominant role of fibrous itssue in tis genesis is postulated.

Adolescent↗
PubMed1976

Congenital aural and pre-auricular sinuses in the South African Bantu.

The incidence of ear pits was studied in the South African Bantu population. A short account of the anatomy, occurrence, inheritance, developmental origin, complications and treatment of this anomaly was given. Mention has been made of the clinical significance and the possible association between ear pits and other systemic and ear abnormalities, including deafness. There seems to be a higher incidence of other abnormalities in children born with sinuses. The blanket term 'pre-auricular fistula' should possibly be discarded in favour of auricular sinuses or ear pits.

Abscess↗