Search PubMed⌕ Search

Biomedical subjects

D Davies

Publications and source records attributed to D Davies.

At least 109 records · Page 6Linked to original sources
PubMed1990

Use of zoospore concentrations and life cycle parameters in determining the population of anaerobic fungi in the rumen ecosystem.

An indirect approach to quantification of the fibrolytic anaerobic fungi in the rumen is described. A mathematical model of the life cycle of anaerobic fungi, based upon observations of the life histories and growth kinetics of these organisms in vitro and in vivo, is constructed and solved in the steady-state to determine the population of particle-attached (substrate-associated) fungal thalli from the concentration of free-swimming zoospores in rumen liquid. The values obtained are broadly consistent with ruminal observations and with observations on faecal populations, which assume that a significant proportion of fungi leaving the rumen (as cysts or spores) can ultimately be accounted for in the faeces.

Animals↗
PubMed1990

Nutritionally induced peripheral neuropathies.

The authors have presented a discussion of some of the more common nutritional deficiency syndromes. A discussion of the etiology, clinical manifestation, diagnosis, and prognosis has been provided. Special attention has been given to the relationship between nutritional deficiency and the development of peripheral neuropathies. When patients suffering from peripheral neuropathy present, the possibility of a nutritional deficiency should be considered. The diagnosis of a nutritional deficiency neuropathy is rarely established. This may not merely be the result of a low incidence of the problem. The prompt diagnosis and treatment may afford dramatic results. The more protracted the course for diagnosis, the less favorable the prognosis. It is often difficult to pinpoint the exact nutritional deficiency present. Various methods have been discussed in this article; however, often multiple deficiencies are present simultaneously. The treatment with pharmacologic supplementation is usually very innocuous. It often proves beneficial to administer pharmacologic supplementation for a short period. This will aid in the differential diagnosis. Often prescribing a patient large doses of the B-complex vitamins for a limited time will allow the physician to determine if a nutritional neuropathy is present. It should also be remembered that just because a patient is suffering from a peripheral neuropathy from a metabolic disease or secondary to medication, they may also be suffering from a nutritional deficiency simultaneously. We believe that the podiatric physician is well trained to extend comprehensive treatment of pedal manifestations of peripheral neuropathies. Podiatric physicians have a large armamentarium at their disposal to treat the pedal manifestations of the disease sufficiently. These treatments may be conservative or surgical in nature, as previously discussed. We hope that this discussion will increase the awareness of the physician to the various ramifications of nutritionally induced neuropathies as well as the provision of insight into the most efficacious means available for appropriate management.

Alcoholism↗
PubMed1989

The use of multiple insulin injection therapy using 'NovoPen' in a routine out-patient setting.

Multiple injection therapy using self-contained cartridge devices such as NovoPen has become a standard option for the treatment of insulin-requiring diabetes in recent years. Such treatment was previously viewed as impractical by the majority of patients and their physicians. Many small pilot studies have suggested that the use of such therapy leads to improvements in glycaemic control. We have many (greater than 200) patients in our clinic who use this form of treatment in the context of a routine out-patient department, where intensive supervision, which characterises all studies involving small numbers, is not practical. We have carried out a questionnaire survey of these patients to ascertain their attitudes to this form of therapy, and made some assessment of its impact on glycaemic control. Multiple injection therapy is a very popular form of therapy, leading to improvements in lifestyle and reduction in frequency of hypoglycaemic symptoms. However, its lack of impact on glycaemic control as estimated by measurement of haemoglobin A1 is disappointing.

Blood Glucose Self-Monitoring↗
PubMed1989

Extraction, pre-high-performance liquid chromatographic purification, and high-performance liquid chromatographic analysis of plant nucleotides.

Problems encountered in obtaining reliable analytical data by HPLC for the free nucleotide constituents of plant tissues are considered and methods of overcoming them experimentally assessed. Major problems include suppression of residual phosphatase activity during extraction, and removal of pigments, phenolics, alkaloids, and other uv-absorbing nonnucleotides, prior to HPLC. An optimal combination of extraction and pre-HPLC purification techniques is discussed which, in combination with HPLC by anion exchange, yields quantitatively reliable data. The optimized procedure involves extraction with a monophasic mixture of methanol: chloroform:formic acid:water and purification of the nucleotide extract by a batch treatment with poly-N-vinylpyrrolidone, followed by ligand-exchange chromatography. The main HPLC separation uses mu Bondapak NH2 in a linear phosphate gradient and gives good resolution of all the commonly occurring plant nucleotides in a single chromatographic run.

Chromatography, High Pressure Liquid↗
PubMed1989

Further evidence for the presence of A antigen on group B erythrocytes through the use of specific exoglycosidases.

Certain antibodies have shown the ability to detect small amounts of A antigenic structures on certain group B cells. These rare cells that reverse group as B, are designated here as B(A) cells. Among the anti-A antibodies capable of detecting these cells are MHO4 (an IgM murine monoclonal antibody) and polyclonal anti-A derived from blood group O donors. The latter (anti-A, B) have been adsorbed exhaustively with normal B cells, to deplete the serum of antibodies to group B antigen. The cell specificity detected by these antibodies can be removed only by an alpha-N-acetylgalactosaminidase (A-zyme) but not by an alpha-galactosidase (B-zyme). Inhibition studies show that these reactions can be inhibited by A secretor saliva and cannot be inhibited by B secretor saliva. Moreover, papain treatment of normal group B cells not previously agglutinable with these antibodies, now causes these cells to become reactive, and this specificity, too, is removed only by A-zyme. These results suggest that low levels of blood group A antigen are being recognized by these antibodies and that these structures can exist not only on B(A) cells but on all group B erythrocytes.

ABO Blood-Group System↗
PubMed1989

The scrapie disease process is unaffected by ionising radiation.

The incubation period of scrapie, its degenerative neuropathology and the replication of its causal unconventional virus are all tightly controlled parameters of the experimental disease in mice. Each parameter can vary depending on the strain and dose of virus, on the route of infection, and on the host genotype. Exposure to whole-body gamma-irradiation from Caesium 137 has no effect on the progress or development of the disease, based on the three independent indices of incubation period, neuropathology, or infectibility by high or low doses of virus. These results are based on an extensive series of experiments in many mouse strains and are consistent using different strains (ME7, 22A, 79A, 87V) and doses of virus, routes of infection, timing and dose of radiation (3-15 Gy) administered as single or fractionated exposures with or without bone-marrow (b.m.) replacement therapy. Levels of infection in the spleen are unaltered after lethal whole-body irradiation of the scrapie-infected host, despite several-fold reductions in tissue mass due to the loss of proliferating myeloid and lymphoid precursor cells and their progeny. Contrary to our earlier suggestion, scrapie infection with the 22A virus does not reduce the effectiveness of post-exposure bone-marrow replacements to recolonise an infected host after repeated ionising radiation totalling 15Gy. This work narrows the search for the candidate cells and biosynthetic systems which replicate the virus in the lymphoreticular and central nervous systems. Many programmed cellular events are radiation sensitive but protein synthesis is extremely radioresistant.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Duplex ultrasonography of the fetal aorta, umbilical artery, and placental arcuate artery throughout normal human pregnancy.

A cross-sectional duplex study of blood flow in the fetal aorta, umbilical artery, and arcuate arteries of 111 normal subjects was performed once at between 20 and 42 weeks gestation. Peak systolic velocity, end-diastolic velocity, mean velocity, and volume flow were measured in the fetal aorta, and systolic to diastolic (S/D) ratios were measured in all three vessels. Velocities show an inverse exponential (Y = Exp [1/X x B + C]) increase with gestational age, reaching a plateau just before term, while S/D ratios in the aorta and umbilical arteries show a linear decrease. Such findings are at variance with some published data. Our results suggest a reduction in fetal placental resistance at term and provide useful data concerning normal fetal and placental circulations.

Aorta↗
PubMed1988

Pulmonary hypoplasia testing in clinical obstetrics.

An ultrasound-based diagnostic test for predicting pulmonary hypoplasia antenatally by measurements of fetal chest circumference was applied prospectively to 45 patients at risk for developing this disorder. The outcome for the newborn infant and the autopsy findings were correlated with the antenatal prediction. The results of this test demonstrated a sensitivity and a specificity of 88% and 96%, respectively. The application of this test to clinical practice is recommended.

Amniotic Fluid↗
PubMed1988

Evaluation of fetal cardiac dysrhythmias with two-dimensional, M-mode, and pulsed Doppler ultrasonography.

Forty-three patients with fetal cardiac dysrhythmia were referred to a tertiary ultrasound department for further evaluation. The patients were subdivided according to the type of dysrhythmia diagnosed. All patients with irregular fetal heart rate had a good perinatal outcome. Of the six patients with fetal tachycardia, two required in utero therapy with maternal digoxin, and one of these fetuses had a cardiac tumor. The eleven patients with fetal bradycardia had the worst perinatal outcome, with four deaths occurring. The results suggest that all patients with fetal tachycardia or bradycardia should have a complete fetal cardiac assessment in a center experienced with the management of such cases.

Algorithms↗
PubMed1988

Atrial natriuretic peptide production in association with nonimmune fetal hydrops.

The presence and elevation of atrial natriuretic peptide in fetuses has not previously been demonstrated. This study of right atrial pacing in fetal lambs demonstrated a threefold to fourfold increase in atrial natriuretic peptide during the production of fetal hydrops. Its rate of return to a normal level paralleled the clearance of fetal hydrops. Its possible role in fetal cardiovascular hemodynamics is discussed.

Animals↗