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Biomedical subjects

M White

Publications and source records attributed to M White.

At least 361 records · Page 20Linked to original sources
PubMed1987

Common elements in growth factor stimulation and oncogenic transformation: 85 kd phosphoprotein and phosphatidylinositol kinase activity.

The phosphorylation of proteins on tyrosine in vivo and in vitro was examined in 3T3 cells stimulated by platelet-derived growth factor (PDGF) and transformed by polyoma middle T antigen (MTAg) by using an antibody directed against phosphotyrosine (P-tyr). Two common events were observed upon PDGF stimulation or MTAg transformation of cells: the appearance in the immunoprecipitates of an 85 kd phosphoprotein, and increased phosphatidylinositol (PI) kinase activity. In PDGF-stimulated cells, the 85 kd phosphoprotein and PI kinase activity appeared rapidly, within 1 min of growth factor addition. The PI kinase activity and 85 kd phosphorylation were also increased in anti-P-tyr immunoprecipitates from cells transformed by v-fms and v-sis, but not by SV40 T antigen. The presence of the tyrosine-phosphorylated 85 kd protein correlated with PI kinase activity during several purification steps. These results suggest that the 85 kd phosphoprotein, a putative PI kinase, is a substrate for both the PDGF receptor and MTAg/pp60c-src tyrosine kinase activities.

1-Phosphatidylinositol 4-Kinase↗
PubMed1987

Epithelial wound healing enhanced by transforming growth factor-alpha and vaccinia growth factor.

Epidermal regeneration following middermal injuries to skin requires both proliferation and migration of keratinocytes. Epidermal growth factor (EGF) stimulates the proliferation of keratinocytes in culture, and topical administration of EGF accelerates epidermal regeneration of partial thickness burns or split-thickness incisions in vivo. Transforming growth factor-alpha (TGF-alpha) and vaccinia growth factor (VGF) have substantial sequence homology with EGF, and all appear to bind to the same receptor protein. Whether TGF-alpha or VGF can affect epidermal wound healing in vivo is not known. The present studies show that topical administration of TGF-alpha or VGF in antibiotic cream to partial thickness burns (second degree) accelerated epidermal regeneration in comparison with untreated or vehicle-treated burns. Low levels of both TGF-alpha and VGF (0.1 microgram per milliliter) appeared to be more effective than EGF in stimulating epidermal regeneration. Regenerated epithelium from burns treated with TGF-alpha or VGF appeared normal histologically. This finding suggests that topical application of selected growth factors may be useful in accelerating healing of partial thickness injuries.

Animals↗
PubMed1987

Pharmacokinetics of propofol in female patients. Studies using single bolus injections.

The pharmacokinetics of propofol in a dose of 2.5 mg kg-1 given via a vein in the antecubital fossa were studied in 18 patients. Anaesthesia was maintained with nitrous oxide in oxygen in all patients. The effects of pretreatment with fentanyl (n = 6) and maintenance with halothane (n = 6) on the pharmacokinetics of propofol were also investigated. Pretreatment with fentanyl resulted in prolonged apnoea in four patients. No serious side effects occurred. The pharmacokinetics of propofol in unpretreated patients who were maintained with nitrous oxide in oxygen only can be described by a three-compartment open mammalian model with very rapid distribution (T1/2 alpha about 3 min), rapid elimination (T1/2 beta 45 min) and a slower final phase (T1/2 gamma about 300 min). The total body clearance of propofol was rapid (1.91 litre min-1). Propofol was initially distributed into a relatively large central compartment (41.3 litre) and was extensively redistributed (Vss 305 litre; V gamma 722 litre). Throughout the sampling period the mean blood concentrations of propofol for the patients pretreated with fentanyl were about 50% higher than the mean concentrations for patients maintained with nitrous oxide only. Mean propofol concentrations for the patients maintained with halothane were intermediate between those of the other two groups.

Adult↗
PubMed1987

Is disordered folate metabolism the basis for the genetic predisposition to neural tube defects?

Vitamin levels were measured in twenty women under 35 years of age with a history of two or more neural tube defect pregnancies. Each index case was compared with a female control matched for age, obstetric history and social class. The mean concentration of red cell folate in the subjects was 178 ng/ml, significantly lower than the mean of 268 ng/ml for the control group (P = 0.005). Red cell folate levels showed a linear relationship with the number of neural tube defect pregnancies, the levels being lowest in women who had had three or four affected offspring. There was no significant difference in serum folate; plasma or white cell vitamin C; plasma vitamin A; thiamine, riboflavine or pyridoxine status; serum vitamin B12; plasma vitamin E; total protein, albumin, transferrin, magnesium, copper or zinc. Diet was assessed by a questionnaire. The dietary intakes of total folate and other vitamins except vitamin A were lower in the subjects than the controls but none of the differences were statistically significant. Regression analysis showed a difference between subjects and controls in the relationship of red cell folate to dietary folate. This study demonstrates an association between susceptibility to offspring with neural tube defects and depressed red cell folate levels which cannot be entirely attributed to a lower dietary intake of folate. It is postulated that one factor predisposing to the occurrence of neural tube defects may be an inherited disorder of folate metabolism.

Adult↗
PubMed1987

First report of the Australian Corneal Graft Registry.

In the Australian Corneal Graft Registry's first 18 months of operation, May 1985 to November 1986, data supplied by 53 surgeons relating to 322 graft recipients have been entered and analysed with respect to: the most common presenting diseases (primarily keratoconus, bullous keratopathy and corneal opacities), risk factors (especially prior sensitisation to HLA antigens, corneal vascularisation, past or present anterior segment inflammation and history of raised intraocular pressure [IOP]), donor and recipient sex, cause of donor death, storage procedures for donor eyes, operative procedures accompanying the grafts themselves, and preliminary indications of overall graft survival by actuarial analysis. It is hoped that the establishment of this Registry will not only reinforce the use of actuarial graft survival analysis as the method of choice for transplantation surgeons wishing to monitor the survival of their patients and grafts, but will also provide a useful service for the Australian ophthalmic community in general.

Actuarial Analysis↗
PubMed1987

Chronotropic response of an activity detecting pacemaker compared with the normal sinus node.

We compared the rate responsiveness of an activity-detecting multiprogrammable, single chamber pacemaker (Medtronic Activitrax) to rate responsiveness of the normal sinus node. This pacemaker changes its basic pacing rate in response to physical activity. The rate responsiveness is programmable by selecting one of three activity thresholds, and one of 10 rate response settings. The study included a group of six normal volunteers and 12 patients implanted with Activitrax to examine the similarity of the pacemaker rate to normal sinus rhythm during acceleration and deceleration. The pacemaker was set to Activity mode, at a basic rate of 60 bpm. In volunteers, the device was externally secured on the chest wall and tested at two programmed settings. When programmed at a high threshold of activity and high rate response in volunteers, there was no significant difference in maximum normal sinus rates and pacemaker rates during arm waving, jumping in place, and walking during stress testing. At a medium activity threshold, the only significant difference occurred during submaximal stress testing, when the maximum sinus rate achieved was 141 +/- 19 bpm and the maximum pacing rate was 105 +/- 8 bpm (p less than .02). The pacemaker behaved in a similar manner in patients, successfully simulating the typical fast acceleration and slow deceleration of a normal sinus node in exercise testing. There was no difference in pacer response when implanted in abdominal or infraclavicular locations. The implanted units have functioned normally over a follow-up period of nine to 22 months. Activitrax can be programmed to achieve physiologic pacing rates in response to normal daily activities with appropriate programming.

Abdomen↗
PubMed1987

Liver metastasis detection: comparative sensitivities of MR imaging and CT scanning.

Twenty patients with known liver metastases were evaluated by unenhanced computed tomography (CT), scans enhanced with ethiodized oil emulsion-13 (EOE-13), and magnetic resonance (MR) imaging with three pulse sequences. Spin-echo (SE) 300/26 (repetition time/echo time, in msec) images prospectively demonstrated 95.4% of the detectable liver metastases; inversion recovery (IR) 1,500/100 (repetition time/inversion time, in msec) images revealed 90.8%; and EOE-13-enhanced CT scans showed 87.1%. SE 2,000/80 images showed 51.4%, and unenhanced CT scans 49.6%, of the metastases. The relationship of vascular anatomy to metastatic foci was best seen on SE 300/26 images and EOE-CT scans. SE 300/26, IR 1,500/100, and EOE-CT studies particularly improved detection of lesions in the 1-2-cm range compared with SE 2,000/80 imaging or unenhanced CT scanning. SE 300/26 and IR 1,500/100 sequences appear comparable to EOE-CT scans in demonstrating liver metastases and significantly superior to conventional CT scans. Because EOE-13 is generally not available, these MR sequences should be the procedure of choice for the diagnosis of liver metastases.

Carcinoma↗
PubMed1986

Babesia bovis: vaccination trial with a dominant immunodiffusion antigen in splenectomised calves.

The dominant immunodiffusion antigen of Babesia bovis was prepared from the lysate of infected erythrocytes by cation exchange chromatography, gel filtration and preparative native acrylamide electrophoresis. It was seemingly free of other babesial antigens and tested as a vaccine. In vaccinated calves, compared to controls, there was a delay in parasitaemia and at times a statistically significant difference in parasite numbers. However, the vaccinates showed little difference in pathophysiological parameters or survival rates from the controls. It was concluded that serodominance cannot necessarily be correlated with protection.

Animals↗
PubMed1986

Rapid isolation in large numbers of intact, viable, individual hair follicles from skin: biochemical and ultrastructural characterization.

A rapid, novel method is described by which large numbers of intact, viable, individual hair follicles may be isolated from rat skin. Follicles are freed from the surrounding connective tissue by shearing, which is effected by repeated cutting with a loosely fitting pair of scissors, and collected individually under liquid using gentle aspiration. Ultrastructural analysis indicates that the follicles are sheared away from the surrounding dermis in the region of the connective tissue capsule which encircles the hair. The follicles appear viable by light and electron microscopy and, within 2 h of isolation, retain the capacity to incorporate [3H]thymidine into DNA and [35S]methionine into proteins as judged by autoradiography. A histologic comparison indicates that the structural integrity of follicles isolated by this new method is significantly superior to those plucked from the animal at the same time. The method affords the isolation of large numbers of hair follicles, without resort to enzyme treatments, suitable for biologic studies in the absence of other skin appendages and dermis.

Animals↗
PubMed1986

Negative explanation, restraint, and double description: a template for family therapy.

Gregory Bateson's notions of negative explanation, restraint, and double description are discussed. The difficulties that families often experience in the discovery of new solutions to problems are explained according to the terms of these notions. A map for therapy is derived that emphasizes the therapist's contribution to the therapeutic system's state of "readiness" for the discovery of new solutions. Details of therapist/family participation in the endurance of new discoveries are examined. An approach to the treatment of the context for childhood fears and obsessive/compulsive behavior demonstrates one application of this map.

Child↗
PubMed1986

Anxiety of non-rooming-in parents of hospitalized children.

This study examined levels of anxiety in 51 parents who did not room in with their young hospitalized children. The Spielberger State-Trait Inventory was used to measure parental anxiety twice, with a 3-day interval. Levels of anxiety were significantly higher in parents with a greater number of children at home, less education, and lower social status. Findings of clinical significance were: the longer the child's hospitalization the more anxious parents became, especially if there were children at home; hospitalization of a child was more stressful for fathers because they maintain lower trait anxiety than mothers; and as parental visits to their hospitalized child decreased, parental anxiety levels increased.

Adult↗