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Biomedical subjects

J G Gray

Publications and source records attributed to J G Gray.

At least 19 recordsLinked to original sources
PubMed1992

Large-scale purification of plasmid DNA by fast protein liquid chromatography using a Hi-Load Q Sepharose column.

The large-scale purification of plasmid DNA was achieved using fast protein liquid chromatography on a Hi-Load Q Sepharose column. This method allows for the purification of plasmids starting from crude plasmid DNA, prepared by a simple alkaline lysis procedure, to pure DNA in less than 5 h. In contrast to the previously described plasmid purification methods of CsCl gradient centrifugation or high-pressure liquid chromatography, this method does not require the use of any hazardous or expensive chemicals. More than 100 plasmids varying in size from 3 to 15 kb have been purified using this procedure. A Mono Q Sepharose column was initially used to purify plasmids smaller than 8.0 kb; however, a Hi-Load Q Sepharose column proved more effective with plasmids larger than 8 kb. The loading of plasmids larger than 8 kb on the Mono Q column resulted in a high back pressure and the plasmid DNA could not be eluted from the column. Thus, for routine purification we utilize the Hi-Load Q Sepharose column. Plasmids purified by this method had purity, yield, and transfection efficiency in mammalian cells similar to those of plasmids purified by CsCl density gradient centrifugation.

Centrifugation, Density Gradient↗
PubMed1992

Three-dimensional imaging for brachytherapy planning.

A computerized 3-D brachytherapy treatment planning program has been developed which simulates catheter trajectories, radioisotope seed positioning and percentage dosimetry zones about a catheter/seed array in relationship to CT or MRI images. The high activity 125I seed is used in this program. A visual and a non-linear mathematical optimization program will also be described.

Brachytherapy↗
PubMed1992

Magnetic resonance imaging and anatomic atlas mapping for thalamotomy.

A computerized anatomic atlas mapping technique has been developed and used to determine target sites for stereotactic thalamotomies. The digitized stereotactic atlases of Schaltenbrand and Bailey, Van Buren and Borke, and Schaltenbrand and Wahren are used in conjunction with an associated electrophysiological data base to determine the intended target site on MR images of the diencephalon. This mapping technique uses the 'Brierley and Beck' proportional hypothesis for thalamic nuclear determination. Target site determination by this method was found to be very accurate, and frequently the mere placement of the probe in the target site resulted in tremor cessation.

Brain Mapping↗
PubMed1992

Three-dimensional whole-brain mapping.

The implementation and use of a computerized whole-brain mapping system which can be used in conjunction with MRI, CT, angiographic and other brain imaging techniques is described. Three mapping systems based upon common reference structures about the third and fourth ventricular core of the brain are used in conjunction with internationally recognized nomenclature to create a normalized whole-brain mapping system according to the Talairach/Tournoux proportional grid technique.

Brain↗
PubMed1991

Human immunodeficiency virus infection and syncytium formation in HeLa cells expressing glycophospholipid-anchored CD4.

The CD4 molecule, a glycoprotein expressed primarily on the cell surface of specific T lymphocytes, is thought to function in T-cell antigen recognition and activation. In addition, CD4 serves as a receptor for human immunodeficiency virus type 1 (HIV-1) by a direct interaction with the HIV-1 surface glycoprotein (gp120). To further characterize the HIV-1-cell interaction, a HeLa cell line was established that expressed a chimeric molecule of CD4 and decay-accelerating factor (DAF). In the chimeric CD4-DAF molecule the transmembrane and cytoplasmic domains of CD4 were deleted and replaced with the carboxy-terminal 37 amino acids of DAF. This resulted in the anchoring of the extracellular domain of CD4 to the cell membrane via a glycophospholipid linkage. The glycophospholipid-anchored CD4 had a molecular size of approximately 56 to 62 kDa and was released following treatment of the cells with phosphatidylinositol-specific phospholipase C. HeLa cells expressing the CD4-DAF hybrid could be infected with HIV-1, as evidenced by reverse transcriptase activity, p24 core antigen content, and infectious virus production. In addition, transfection of the HeLa CD4-DAF cells with a plasmid that directs the synthesis of HIV-1 envelope glycoproteins or cocultivation with HeLa cells expressing the virus glycoproteins resulted in syncytium formation. These results indicate that the transmembrane and cytoplasmic domains of the CD4 molecule are dispensable for both HIV infection and syncytium formation.

Acquired Immunodeficiency Syndrome↗
PubMed1991

A new breast screening programme--an audit of the first year.

The experience of a new breast screening unit is reported. In the first 12 months there was a 72.1% response rate with 9890 women being screened. After the initial screen 598 (5.8%) were referred to the Assessment clinic. Following repeated mammography and clinical examination 166 patients were referred for a surgical opinion; 105 (1.06% of the total screened) were considered to be possibly malignant; 61 further patients with clinical and mammographically benign disease were kept under review by a single surgeon; 101 patients had excision biopsies; 28 of 32 palpable breast lumps and 36 of 69 non-palpable lesions proved to be malignant.

Biopsy↗
PubMed1990

Stomal adenocarcinoma in Crohn's disease.

Malignant change occurring at the site of a stoma in two patients with proved Crohn's disease is described. Patients with ulcerative colitis have an increased risk of colonic malignancy and Crohn's disease is also associated with both small and large bowel carcinoma. Most previous reports of stomal carcinoma have been associated with ulcerative colitis although Crohn's disease seems to carry a greater risk of associated small bowel carcinomas. This is the first report of stomal carcinoma complicating Crohn's disease. Epithelial dysplasia is associated with gastrointestinal carcinomas in both ulcerative colitis and Crohn's disease and a dysplasia-carcinoma sequence has been suggested as the origin of these tumours. In both our patients with stomal adenocarcinoma, dysplasia was identified in adjacent tissues, which suggests a similar mechanism. Malignant change should be suspected if epithelial dysplasia is discovered in a biopsy specimen from the mucosa of an ileostomy in Crohn's disease, and this risk is increased if the dysplasia is of a high grade.

Adenocarcinoma↗
PubMed1986

Aspiration cytology and ultrasonography of cold thyroid nodules.

Over an 18 month period, 50 'high risk' patients with solitary or dominant cold thyroid nodules on 99m Tc-pertechnetate scanning, have undergone fine needle aspiration biopsy cytology (ABC) under general anaesthetic prior to thyroidectomy. Histological malignancy was confirmed in only four patients (8%). Cytological malignancy was suspected or confirmed in six patients, each having a false positive rate of 4%. There were no false negative reports. Ultrasonography, performed pre-operatively in 37 of the patients, did not significantly add to the overall patient management. ABC appears to be safe, simple and sufficiently accurate to incorporate its use routinely in the pre-operative assessment of thyroid nodules.

Adult↗
PubMed1985

An Alcaligenes faecalis isolate from turkeys: pathogenicity in selected avian and mammalian species.

An Alcaligenes faecalis isolate of known pathogenicity for turkeys was examined for adherence and cytotoxicity in tracheal organ cultures of turkeys, chickens, Japanese quail, guinea pigs, hamsters, and mice, and for colonization and pathogenicity in these 6 species. Adherence and colonization were detected by fluorescent antibody staining. Infected and noninfected tracheal rings were examined by phase-contrast microscopy for cytotoxicity (ciliostasis, blebing of the cell membrane, and sloughing of the ciliated epithelium). Alcaligenes faecalis adhered to the tracheal rings of all species examined. Cytotoxicity was apparent in the tracheal rings of turkeys, quail, and chickens. Cytotoxicity was not detected in tracheal rings from the mammalian species. Alcaligenes faecalis colonization of turbinates and tracheas of intact turkeys and quail was detected. Clinical signs of alcaligenes rhinotracheitis were observed and histopathologic characteristics of the disease were detected. Chickens, guinea pigs, hamsters, and mice were refractory to infection with this isolate of A faecalis.

Adhesiveness↗
PubMed1979

Value of 1-alpha-hydroxy vitamin D3 in treatment of primary hyperparathyroidism before parathyroidectomy.

The postoperative course of six patients with primary hyperparathyroidism and obvious radiological evidence of bone disease pretreated with 1-alpha-hydroxy vitamin D3 (1 alpha HCC) was indistinguishable from that of six patients with a similar clinical and radiological picture who were not pretreated. 1alphaHCC may increase the hypercalcaemia in some cases and cannot be recommended for the routine preparation of such patients for surgery.

Adolescent↗
PubMed1976

Definitive emergency treatment of perforated duodenal ulcer.

A retrospective survey was made of all patients with a proved diagnosis of perforated duodenal ulcer admitted to a regional hospital during a recent six year period. The over-all mortality from this condition in the 192 patients was 11.4 per cent and mortality after operation, 6.3 per cent. One hundred and seventy-six patients were treated surgically. Seventy-seven patients underwent simple suture only with a mortality of 13 per cent and are compared with 99 patients treated by emergency vagotomy and pyloroplasty procedures with a 1 per cent mortality. Emergency definitive operations were performed without increased morbidity, mortality or hospital stay by junior surgeons with greatly improved long term results compared with simple suture. At the present time, emergency vagotomy and pyloroplasty procedures are the treatment of choice for a perforated duodenal ulcer.

Adolescent↗
PubMed1975

Compartments and cell flows within the mouse haemopoietic system. II. Estimated rates of interchange.

Part-body irradiated CBA mice were injected with CBA-T6 bone marrow. In this way a predominantly donor population was established in the femora while the marrow of the humeri remained largely (average 94%) of host origin. In animals examined cytologically up to 2 years later, no tendency was observed for the proportion of donor cells in the humeri to increase. Splenectomy had no effect on this. When femoral bone marrow from the experimental mice was injected into lethally (whole-body) irradiated recipients, cells originating from the primary host repopulated the lymph nodes to a disproportionate extent. Equilibration between the cell populations of femora and humeri occurred after re-exposure to 600 rad whole-body irradiation, but not after 100 rad or 350 rad; thus, regeneration of damaged bone marrow involved a significant contribution from extrinsic stem cells only after the highest dose of radiation. The data are compatible with an inflow of at most ten effective stem cells per humerus per day from the blood, and suggest a much lower figure. This means that few if any of the stem cells of peripheral blood enter the bone marrow and found haemopoietic clones. Evidence is adduced for the existence of a proliferating lymphoid sub-population in the bone marrow, contributing some 5-10% of the observed mitoses. The mitotic cells in the lymph nodes are replaced from marrow-derived progenitors at an estimated rate of 4-5%/day. The relevant data for the thymus are more variable, but suggest an average figure of 8-11%/day. Earlier data from mouse parabionts suggest a lower rate of inflow to the thymus.

Animals↗
PubMed1975

Acute reversible renal failure in patients with acute cholecystitis and cholangitis.

Although acute renal failure is a well recognized complication of several extra-hepatic biliary tract diseases especially biliary tract surgery in the presence of obstructive jaundice, there is little information concerning renal failure in acute cholecystitis. Renal function was assessed in 14 patients with acute cholecystitis and two with acute cholangitis. Six patients had no evidence of renal impairment, four had modest elevations of plasma urea and creatinine concentrations and six had acute reversible renal failure of whom three required peritoneal dialysis. Only one patient was hypovolaemic and in the remainder there was evidence that intravasular coagulation was responsible for the renal failure. It is suggested that bacteraemia was the initiating factor. The therapeutic implications of these findings are discussed.

Acute Disease↗