Search PubMed⌕ Search

Biomedical subjects

D Clark

Publications and source records attributed to D Clark.

At least 343 records · Page 19Linked to original sources
PubMed1979

A morphometric study of the cochlea of the little brown bat (Myotis lucifugus).

A detailed morphometric study of the basilar membrane was made from serial sections and graphic reconstructions of the cochlea of three little brown bats. Four distinct morphometric changes were observed within the basilar membrane. First, between 0-1.4 mm from the basal end of the cochlea, there is a rapid increase in width and cross-sectional area of the basilar membrane. Secondly, between 1.4-2.5 mm, there is little change in width of the basilar membrane (its cross-sectional area is at its greatest in this region). Thirdly, between 2.7-3.1 mm, there is a sudden decrease in cross-sectional area concomitant with an increase in the width of the basilar membrane. Finally, between 3.1 mm and the apex, there is a gradual decrease in cross-sectional area concomitant with an increase in the width of the basilar membrane. The magnitudes of the cross-sectional areas of the scalae media and vestibuli decrease from base to apex, but this is not true for the scala tympani. The cross-sectional area of the scala tympani appears to decrease from the base to 0.7 mm, then it increases up to 1.4 mm, and then it decreases to the apex. These morphometric changes in the basilar membrane of the little brown bat are compared to those in other echolocating and non-echolocating mammals. The significance of these changes is discussed in relation to the range of hearing in the little brown bat.

Animals↗
PubMed1979

Immunoglobulin synthesis by lymphoid cells transformed in vitro by Abelson murine leukemia virus.

The majority of cell lines derived by infection of murine bone marrow cells with Abelson murine leukemia virus (A-MuLV) synthesize a mu chain but no detectable light chain. Aside from this mu-only phenotype, lines that make only light chain, both chains or no immunoglobulin-related polypeptides have also been found. Two lines have been studied in detail: one that makes only mu chain and one that makes only kappa light chain. Synthesis of both polypeptides can be increased by modifying the culture conditions so as to decrease the growth rate of the cells. Although some kappa chain secretion was observed, neither secreted nor surface mu was detected. We suggest that the mu- only phenotype may be an early normal step in the pathway of B lymphocyte maturation.

Animals↗
PubMed1979

The relation between respiratory illness in primary schoolchildren and the use of gas for cooking--II. Factors affecting nitrogen dioxide levels in the home.

The study was designed to determine whether there was an association between indoor levels of nitrogen dioxide (NO2) and respiratory illness and lung function in schoolchildren. NO2 was measured for one week in the winter outside and inside the homes of children aged 6-7 years living and attending primary schools in a defined 4 square km area in Middlesbrough, Cleveland, UK. Outdoor levels of NO2 measured at 75 points within the area ranged from 14-24 ppb weekly average. Measurements were also made in 428 kitchens with gas cookers, range 5-317 ppb, mean 112.2 ppb, and in 87 kitchens with electric cookers, range 6-188 ppb, mean 18.0 ppb. In a random subsample of homes the range of NO2 levels in 107 children's bedrooms in homes where gas was used for cooking was 4-169 ppb, mean 30.5 ppb, in 18 bedrooms in electric cooking homes the range was 3-37 ppb, mean 13.9 ppb. NO2 levels in the gas cooking kitchens were positively related to the presence of pilot lights, use of gas fires for main heating, number of regular smokers, and the number of people in the home. Information from 29 homes with the highest kitchen NO2 levels paired with 29 low NO2 gas cooking homes showed that the daily number of meals eaten and the frequency with which the cooker was used for heating and drying clothes were significantly greater in the high NO2 homes.

Air Pollutants↗
PubMed1978

A reappraisal of the interaction between tricyclic antidepressants and reserpine-like drugs.

The administration of trycyclic antidepressants followed by reserpine-like drugs elicits a pattern of stereotyped locomotor activity. Using desmethylimipramine (DMI) followed by tetrabenazine (TBZ), activity could be reliably elicited only in young rats, and only by using very high doses of TBZ. The latency of onset of activity was up to 5 h. Animals rendered active by DMI-TBZ failed to perform a well-established operant task. The activity syndrome was apparently unaffected by pre- or posttreatment with the dopamine antagonists spiroperidol or primozide, but partial antagonism was obtained with the noradrenaline antagonists phentolamine and phenoxybenzamine. The findings are discussed in relation to the mechanism of action of the effect and its relevance to the clinical action of tricyclic antidepressants.

Animals↗
PubMed1978

Effects of induced hyperopia.

Hyperopia of 1.00, 1.50, and 2.00 D was induced in 42 subjects by means of concave lenses. A significant decrease in performance on a standard intelligence test occurred with the highest-power lenses. Symptoms induced indicate that the results are applicable to hyperopia. Prescriptions and vision screening criteria for hyperopia are indicated.

Adolescent↗
PubMed1978

Dialysability of theophylline.

We have shown that theophylline is highly dialysable with an average dialysis clearance of 76 ml/min approaching 63% of urea clearance with hemodialysis. Implications include dose adjustment during dialysis and efficacy of dialytic technique in the treatment of theophylline intoxication.

Blood Glucose↗
PubMed1977

Further mapping of several membrane lipid biosynthetic genes (fabC, fabB, gpsA, plsB) of Escherichia coli.

New genetic mapping data on several loci involved in membrane lipid synthesis are reported. We demonstrated that the lesion designated fabC by Broekman and Hoeckstra (Mol. Gen. Genet. 124:65-67, 1975) is a fabB mutation. In the course of this work, the orientation of the pdxB and fabB loci was determined. The order of the loci is fabB pdxB purF. We also report cotransduction between the gpsA and cysE loci and show that the order of these markers is mtl cysE gpsA. Cotransduction between the plsB and kdgK loci was also sought. Despite extensive experiments, we were unable to detect cotransduction between these loci. In addition, we were unable to detect cotransduction among several markers in region 46 to 48 min of the map.

Chromosome Mapping↗
PubMed1976

Patterns of extension as a guide to radiation therapy in the management of ovarian neoplasms in children.

Sixteen cases of childhood malignant ovarian neoplasms of varied histology and stages were reviewed with special reference to the patterns of disease extension within the pelvis and abdomen. All patients had initial surgery elsewhere before referral to Memorial Hospital. Two patients had distant metastases (bone and lung). None of the other 14 girls had disease restricted to the pelvis. The first extension in 11 was to sites within the abdominal cavity as well as to the pelvis and in three to the abdomen without pelvic involvement. Total abdominal irradiation would have been required to encompass all known disease-bearing areas in these 14 girls.

Abdominal Neoplasms↗
PubMed1976

Structure activity studies on somatostatin.

Seven synthetic analogues of somatostatin helped clarify structural requirements for suppression of growth hormone secretion in rats. Size of the ring is not critical; deletions of serine-13, lysine-4 or asparagine-5 result in peptides which retain an appreciable fraction of the activity. The analogue des-Ala1, Gly2, Asn5-somatostatin lowers plasma growth hormone and insulin levels without affecting plasma glucagon levels significantly.

Amino Acid Sequence↗
PubMed1976

Prolonged pneumococcal meningitis due to an organism with increased resistance to penicillin.

For more than 30 years, penicillin has been the agent of choice for pneumococcal infections. During this time the majority of strains of Streptococcus pneumoniae have been highly susceptible to penicillin. However, during the last ten years there have been sporadic reports of pneumococci with increased resistance to penicillin. The case report of an 18-month-old white boy with meningitis due to a strain of S. pneumoniae with increased resistance to penicillin is presented. The MIC of the organism to penicillin was 0.2 mug/ml and the MBC 0.39 mug/ml. The patient had normal immunity and no demonstrable sequestered focus of infection but failed to respond to appropriate doses of intravenous penicillin. Treatment with chloramphenicol caused a dramatic bacteriologic and clinical response. This experience reemphasizes the existence of pneumococcal strains of intermediate penicillin sensitivity and the importance of in vitro susceptibility tests.

Humans↗