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Biomedical subjects

D R Williams

Publications and source records attributed to D R Williams.

At least 289 records · Page 16Linked to original sources
PubMed1978

Similarity of clinical and laboratory results obtained with microporous teflon membrane oxygenator and bubble-film hybrid oxygenator.

For 80 elective clinical cardiopulmonary bypasses we alternately used either a commercial microporous Teflon membrane oxygenator or a commercial hybrid bubble-film oxygenator. Setup time was a little longer with the membrane unit (20 minutes), but priming volume (2,250 ml) was the same. No problems were encountered with the hybrid oxygenator. However, despite our monitoring of additional variables, including shim and inlet pressure and recirculation flow, gas exchange abnormalities were encountered in 5 patients on whom the membrane oxygenator was used; in 4 of these cases the abnormalities were encountered prior to our recognition of the potential for occasional internal shunting with this device. There were no hospital deaths. When the two groups, matched except for oxygenator selection, were compared, there were no significant differences clinically or hematologically. For cardiopulmonary bypass of 2 hours or less, both oxygenators studied are definite improvements over previous silicone membrane and high-gas-flow bubble oxygenators. However, lower cost and reduced complexity favor the hybrid oxygenator.

Blood Glucose↗
PubMed1978

The esterase D polymorphism in patients with diabetes or carcinoma of the bladder and a matched sample of non-donor controls.

Results are reported for the Esterase D polymorphism in a sample of the general population from the Durham area. Gene frequencies agree well with those previously reported from the north of England. No differences are revealed when the sample is subdivided on the basis of age. No significant differences are observed between this sample and two disease series from the same region, one with diabetes, the other with carcinoma of the bladder. This holds true when the disease groups are considered with regard to current age, age at diagnosis, and in the case of the diabetic, current treatment.

Adolescent↗
PubMed1978

Antiserum to the cell surface of oral epithelial cells: relationship to pemphigus antiserum.

Antisera to human oral epithelial cells were produced in rabbits and found to be specific for epithelial type cells of man, guinea-pig and rabbit. Binding of the antisera to human oral epithelial cells was not affected by pre-incubation in concanavalin A, trypsin or neuraminidase, nor by pre-incubation of the antisera with fetuin. The antisera would appear to differ from pemphigus antiserum.

Animals↗
PubMed1978

Increased HLA-B heterozygosity with age.

427 healthy individuals ranging in age from 16 to 101 years were tested for HLA-A and -B antigens. No significant differences were found for any particular antigen according to the age of the individual. However, a significant trend of increasing frequency with age was found for individuals possessing two detectable HLA-B antigens. An apparent trend of increasing frequencies for individuals possessing four HLA-A and -B antigens was not significant. These results concur with those of some previously published studies.

Adolescent↗
PubMed1978

Denitrifying Pseudomonas aeruginosa: some parameters of growth and active transport.

Optimal cell yield of Pseudomonas aeruginosa grown under denitrifying conditions was obtained with 100 mM nitrate as the terminal electron acceptor, irrespective of the medium used. Nitrite as the terminal electron acceptor supported poor denitrifying growth when concentrations of less than 15 mM, but not higher, were used, apparently owing to toxicity exerted by nitrite. Nitrite accumulated in the medium during early exponential phase when nitrate was the terminal electron acceptor and then decreased to extinction before midexponential phase. The maximal rate of glucose and gluconate transport was supported by 1 mM nitrate or nitrite as the terminal electron acceptor under anaerobic conditions. The transport rate was greater with nitrate than with nitrite as the terminal electron acceptor, but the greatest transport rate was observed under aerobic conditions with oxygen as the terminal electron acceptor. When P. aeruginosa was inoculated into a denitrifying environment, nitrate reductase was detected after 3 h of incubation, nitrite reductase was detected after another 4 h of incubation, and maximal nitrate and nitrite reductase activities peaked together during midexponential phase. The latter coincided with maximal glucose transport activity.

Aerobiosis↗
PubMed1978

Comparison of the genomic organization of Kirsten and Harvey sarcoma viruses.

Current studies were undertaken to compare the genomes of Kirsten murine sarcoma virus (Ki-MuSV), Harvey murine sarcoma virus (Ha-MuSV), and the replication-defective endogenous rat virus to understand the function of these viral RNAs. Genome organization and sequence homology were studied by fingerprinting large RNase T1-resistant oligonucleotides and by cross-protecting homologous oligonucleotides against RNase A and T1 digestion with complementary DNA prepared from each of the other viral RNA. Ki-MuSV and Ha-MuSV were found to share an extensive series of rat-derived oligonucleotides begining ca. 1 kilobase (kb) from the 3' end and extending to within 1.5 kb of the 5'end of Ki-MuSV RNA. The total map distance covered in ca. 5.5 kb. The eight oligonucleotides covering the 1.5 kb at the 5' end of Ki-MuSV RNA were not found in Ha-MuSV RNA. Five out of these eight oligonucleotides, however, could be designated with certainty to be of rat virus origin. Since Ha-MuSV is 6.5 kb in size and Ki-MuSV is 8 kb in size, the major difference between them is the 1.5 kb from the replication-defective endogenous rat virus sequences at the 5' end of Ki-MuSV not present in Ha-MuSV. Consistent with the difference in the genome structure, these two sarcoma viral RNA'S yielded distinct major translation products in cell-free systems, I.E., A 50,000-dalton polypeptide (P50) from Ki-MuSV and a 22,000-dalton polypeptide (p22) from Ha-MuSV. These polypeptides may provide the necessary protein makers for identifying in vivo virus-coded proteins.

Base Sequence↗
PubMed1977

The borderline patient and conservative treatment in the late mixed dentition.

1. The possibilities for successful conservative treatment of mild lower arch length deficiencies (2 to 5 mm.) are explored for twenty growing patients in the late mixed dentition. 2. Methods of case selection and treatment particulars are presented. 3. Each patient should be considered as an individual with regard to cephalometric norms for the optimal position of the incisors, in determining the size of the leeway space at the lower second deciduous molar position, in evaluating the feasibility of distal uprighting the lower first permanent molars, and in formulating a reasonable treatment plan. 4. It is postulated that oversized lower second deiduous molars may be an etiologic factor in some mild lower arch length deficiencies (r = 0.4; P less than 0.05). 5. The amount that the lower first premolars and lower canines can be distally retracted into the leeway space in these conservatively treated cases is directly related to retraction of the lower incisors (r = 0.7; P less than 0.01). In the present cases uprighting the lower incisors allows the upper teeth to be treated well and together this enables functional and esthetic improvement and tooth stability.

Bicuspid↗
PubMed1977

The changing status of ejection fraction as a predictor of early mortality following surgery for acquired heart disease.

Several reports in the literature and our experience prior to 1974 support the thesis that operative risk in patients with acquired heart disease and poor ventricular function (as assessed by a biplane ejection fraction [EF] less than or equal to 0.40) was very significantly increased over the risk in patients with normal ventricular function. These results led to disagreement in the literature regarding the advisability of surgery in patients with poor ventricular function. Various EFs from less than 0.31 to less than 0.50 were suggested as contradicting elective surgery, while more aggressive groups recommended surgery in all patients with angina. Precise comparison of the results reported by different groups was not always possible because of the common reliance on single-plane right anterior oblique ventriculograms, which tend to underestimate EF and overestimate operative risk. Using biplane ventribulograms for accurate estimation of EF, we have demonstrated a significant reduction in 30-day operative risk to a clinically acceptable 3 percent (1/32) for single valve replacement and aortocoronary surgery patients with poor ventricular function (EF less than or equal to 0.40) during 1974. Considering the high risk of medically treated patients with reduced ventricular function, these results support further evaluation of surgical palliation for patients with valvular or coronary heart disease and reduced ventricular function.

Cardiac Volume↗
PubMed1977

Associative interaction: joint control of key pecking by stimulus-reinforcer and response-reinforcer relationships.

The joint control of rate of key pecking in pigeons by stimulus-reinforcer and response-reinforcer relationships was studied in the context of a two-component multiple schedule of reinforcement. Food presentation was always associated with one component and extinction with the other. The stimulus-reinforcer relationship was manipulated by varying the relative durations of the two components. In the food-presentation component, a fixed rate of reinforcement, independent of rate of responding, was generated by a schedule referred to as "T*". One aspect of the response-reinforcer relationship, contiguity, was manipulated by varying the percentage of delayed reinforcers. With the multiple T* extinction schedule, stimulus-reinforcer and response-reinforcer relationships could be varied independently of one another. Rate of key pecking was sensitive to manipulations of both relationships. However, significant differential effects due to either the stimulus-reinforcer or response-reinforcer relationship were obtained only when the other relationship was weak: stimulus-reinforcer and response-reinforcer relationships interacted in the joint control of responding.

Journal Article↗
PubMed1976

The associative relation underlying autoshaping in the pigeon.

Fifteen pigeons were exposed to either response-independent or response-dependent schedules of water reinforcement, whereby water was injected directly into the unrestrained pigeons' mandibles. Key-contact responses were released by a lighted key correlated with water, but not by a lighted key uncorrelated with water. A negative response-reinforcer contingency suppressed autoshaped key-contact responses, resulting in responding directed away from the lighted key. In all pigeons, water injected directly into the mandibles elicited a consummatory fixed-action pattern of "mumbling" and swallowing. The lighted key correlated with water released a broader set of both appetitive and consummatory responses: approach to the lighted key, "bowing", "rooting", "mumbling", and swallowing. Key-contact responses were "rooting" and "mumbling" motions of the beak on the surface of the key. Views of autoshaping based on stimulus substitution or stimulus surrogation do not fully explain the origin of autoshaped responses not previously elicited by the reinforcer. The present findings are consonant with views of conditioning that emphasize the large degree of biological pre-organization in conditioned response patterns, and the importance of associative factors in the control of such patterns.

Journal Article↗