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Biomedical subjects

R W Williams

Publications and source records attributed to R W Williams.

At least 163 records · Page 9Linked to original sources
PubMed1982

Prenatal development of retinocollicular projections in the cat: an anterograde tracer transport study.

The retinal projection to the superior colliculus of the cat was examined at four gestational ages, embryonic days 38, 46, 56, and 61, using the antegrade transport of horseradish peroxidase and tritiated leucine. Gestation in the cat averages 65 days. By the 38th day of gestation (E38), the anlage of the entire superior colliculus, both ipsilateral and contralateral to an injection, was labeled intensely. The peroxidase label had an extremely coarse grained texture. As late as E46, the ipsilateral retinal projection extended to the presumed caudal border of the colliculus, while by E56, as in the mature cat, the ipsilateral terminal field was largely excluded from the rostral and caudal tectal poles. The contralateral terminal field at E56, as in younger fetal material, extended across the entire tectal mantle. By E61, clear gaps of label were observed in the contralateral stratum griseum superficiale. At this age, patches or bands of label were accentuated on the ipsilateral side. In double labeled tissue, it could be demonstrated that the ipsilateral patches corresponded quite closely to the gaps in the contralaterally derived label. Thus, a few days before birth, the retinal projection to the superior colliculus has a pattern which resembles that of the adult.

Afferent Pathways↗
PubMed1981

Lipid-tail group dependent structure of the fd gene 8 protein.

Using circular dichroism several laboratories have shown that the fd coat protein can assume three distinct conformations depending on the conditions. We have reinvestigated these three conformations using laser Raman spectroscopy and the quantitative estimates of alpha-helix by Raman agree fairly well with the earlier estimates obtained by CD. In addition, we have studied in more detail the conditions governing the 3 conformations. To our surprise, the nature f the lipid tail group seems to be the determining factor for two of the conformations. A lipid tail group dependence of protein structure is without precedent and has potential consequences for the assembly of filamentous phages as well as for the structure and function of cell membranes.

Circular Dichroism↗
PubMed1979

Ultraviolet and laser Raman investigation of the buried tyrosines in fd phage.

The tyrosines of the filamentous phage fd have been found to be inaccessible to solvent by pH titration while monitoring the ultraviolet spectrum or the laser Raman spectrum. The uv spectra suggest that the tyrosines do not become deprotonated unless the phage becomes disrupted. One possible explanation of the Raman spectra is that the tyrosine OH groups are the recipients of hydrogen-bonded protons arising from fairly acidic donors, yet these acidic donors do not become titrated over the pH 7 to 12 range.

Coliphages↗
PubMed1979

Laser Raman studies of lipid disordering by the B-protein of fd phage.

Complexes of the B-protein of fd phage with the model lipid dipalmitoyl phosphatidylcholine (DPPC) were made by sonication of the fd phage in the presence of dipalmitoyl phosphatidylcholine. Both laser Raman spectra and circular dichroism show the protein in the membrane to be almost entirely in the beta-sheet conformation. This beta-sheet conformation is found to be independent of the temperature between 10 degrees C and 50 degrees C. On the other hand, the protein has a very dramatic effect on the organization of the lipid bilayer. An aqueous dispersion of 1 : 1 lipid/protein mixture gives a broad conformational transition of DPPC which occurs between 10 degrees C and 30 degrees C. This contrasts markedly with simple aqueous DPPC dispersions which show a sharp transition at 41 degrees C. This appears to be the first reported example of the lowering of the conformational transition of a membrane bilayer by an intrinsic membrane protein.

Coliphages↗
PubMed1978

Microlumbar discectomy: a conservative surgical approach to the virgin herniated lumbar disc.

Microlumbar discectomy is an extremely conservative microsurgical procedure for the treatment of the virgin herniated lumbar disc. The technique has been utilized in 530 patients over a 5 1/2-year period, and features no laminectomy or curettement of the disc space. Preservation of extradural fat and blunt perforation of the annulus fibrosus, rather than scalpel incision, appear to minimize reherniations and adhesion reactions. Operating time has averaged 37 minutes and postoperative stay 3.1 days during the past 36 months (46% of these were compensation cases). In this series, a satisfactory result is defined as those patients who remain economically productive and physically comfortable at the time of followup. Satisfactory results were achieved in 91% of patients after one procedure.

Adolescent↗
PubMed1978

Experimental pancreatitis: Effect of plasma and dextran on pancreatic blood flow.

In spite of extensive investigations, many aspects of the hemodynamic changes occurring in acute pancreatitis are understood poorly. A dog model was established in which continuous measurements of pancreatic arterial blood flow, cardiac output, and mean arterial blood pressure were made using electromagnetic flow probes and a pressure transducer, respectively. Pancreatitis was induced and the animals were monitored for 3 hours. In addition, control animals (group I) without pancreatitis also were done. All animals 50 ml of saline in the first hours. Three methods of therapy then were instituted in the dogs with pancreatitis and their effects were recorded. group I 6 dogs control animals no pancreatitis saline 50 ml/hr group II 10 dogs saline 50 ml/hr group III 6 dogs plasma 15 ml/kg over 45 min then saline 50 ml/hr group IV 10 dogs saline 50 ml and 1.5 ml/kg of dextran 40/hr These results confirm the observations made previously using a transillumination technique--that the pancreatic circulation rapidly reduces in acute pancreatitis. Administration of plasma produced a significant (P less than 0.05) but transient increase in the cardiac output and pancreatic blood flow; however, the blood pressure remained low. Dextran 40 minimally increased cardiac output, but it significantly improved the blood pressure and maintained the pancreatic blood flow. Low-dose, low-molecular weight dextran 40 appears to help to maintain pancreatic blood flow in acute pancreatitis. The possible mechanisms concerning the made of action of dextran 40 will be discussed.

Animals↗
PubMed1975

Mixed tumor of female breast of unusual duration and size.

A 72-year-old black woman presented with huge enlargement of the right breast beginning approximately 30 years earlier and progressively enlarging over the years. The breast was stony hard, painless, and inconvenient only because of size and weight. Simple mastectomy was done and pathologic examination showed a benign mixed tumor with large areas of pseudocartilage, osteoid, and bone formation. Preoperatively the serum calcium was 11.0 mg/100 ml and alkaline phosphatase, 550 mU/ml (SMA-12). Postoperative course was uneventful and within several weeks the alkaline phosphatase fell to a normal range (35-115 mU/ml). The case presented requires little comment other than its unusual nature and duration. Extensive bone formation was undoubtedly responsible for the elevated alkaline phosphatase and, as expected, it returned to normal limits following excision of the tumor. Simple mastectomy is considered the treatment of choice.

Aged↗