Search PubMed⌕ Search

Biomedical subjects

J R Thomas

Publications and source records attributed to J R Thomas.

At least 145 records · Page 8Linked to original sources
PubMed1990

Comparison of culture and serology for the diagnosis of cytomegalovirus infection in kidney and liver transplant recipients.

This study compared culture, including the shell vial procedure, with serology, including IgM cytomegalovirus (CMV) antibody testing, for the diagnosis of CMV infection in 42 subjects undergoing cadaveric renal or liver transplantation. Of 35 subjects who developed active CMV infection, 31 had positive cultures, while IgM CMV antibodies were detected in 29. Subjects with symptomatic CMV infection were more likely than asymptomatic subjects to have positive cultures of leukocytes (17/18 vs. 9/17, P = .01). In contrast, symptomatic and asymptomatic subjects did not differ in their IgG or IgM CMV antibody test responses. In subjects with symptomatic infection, viral shedding typically began early in the course of infection, often preceding symptoms, while the serologic response usually followed the appearance of symptoms. With the use of the shell vial procedure to facilitate detection of positive cultures, symptomatic CMV infections following kidney or liver transplantation can be recognized earlier and more reliably using viral culture than by serologic testing.

Adult↗
PubMed1990

Adrenergic responses to cognitive activity in a cold environment.

Adrenergic responses during physical stress such as cold exposure have been reported to differ from those responses observed during cognitive activity. Both the separate and the combined effects of cold and cognitive activity on catecholamine activity were examined in six male subjects. Alterations in plasma epinephrine and norepinephrine showed different patterns as a function of exposure to a 4 degrees C cold environment, a cognitive performance assessment battery (PAB), and the two conditions combined. Plasma epinephrine was not altered by exposure to cold and only slightly increased by PAB performance when given at 23 degrees C. However, epinephrine was substantially elevated by exposure to combined cold and PAB. Heart rate changes paralleled observed changes in epinephrine. Norepinephrine release was predominantly increased by cold exposure and was not altered by PAB performance.

Adult↗
PubMed1990

Surgical therapy of the eyelids in patients with facial paralysis.

Patients with facial paralysis have a degree of lagophthalmos and paralytic ectropion. We present our experience in the surgical management of 25 consecutive patients treated for these problems. Paralytic lagophthalmos was corrected using gold weights inserted into the upper eyelid. The advantages and disadvantages of this surgical technique are reviewed. Medial canthoplasty and lateral canthoplasty were performed to rectify paralytic ectropion. Ancillary procedures included browpexy, upper-lid blepharoplasty, and temporalis sling. The results were excellent in 23 of 25 patients and good in the remaining two. After a minimum of 6 months' follow-up, there were no complications. The authors believe that the above procedures will yield consistently excellent cosmetic and functional results in patients with paralysis of the eyelids.

Cranial Nerve Neoplasms↗
PubMed1990

Skin grafts.

The techniques of partial-thickness and full-thickness skin grafting are reviewed, including choice of donor site, preparation of recipient site, graft harvesting, and postoperative dressings and care. A review of the basic principles of skin graft healing is included to increase understanding of the reasons these techniques are used and to show how to avoid complications associated with skin grafting. The areas of usefulness of skin grafts are discussed in relation to the face, head, and neck.

Face↗
PubMed1990

Scar revision and camouflage.

The successful revision and camouflage of facial scars is as much an art as a science, and the best teacher is continued experience; however, common sense, a broad knowledge of available options, technical ability, and patience are all necessary if one chooses to practice in this challenging field. Patients with facial scars are vulnerable in a way that few others are, and it is the responsibility of the facial plastic surgeon to evaluate these patients properly and realistically, to prepare them for a process that may involve multiple procedures, and to see them through this process with all the expertise and compassion possible. If this is done, the rewards to the patient and to the surgeon can be immeasurable.

Cicatrix↗
PubMed1990

[Long-term decrease of microalbuminuria after one year of treatment with perindopril in hypertensive diabetic patients].

We studied the effects of perindopril, an angiotensin converting enzyme (ACE) inhibitor administered during 12 months, on creatinine clearance, albuminuria and glycaemic control in diabetic subjects with mild to moderate hypertension. After 1 month placebo, 40 insulin-treated patients were divided into 3 groups based upon their urinary albumin excretion rate. Group 1 had a normoalbuminuria (less than 15 mg/24 h), group II had a microalbuminuria (15-150 mg/24 h) and group III had a macroproteinuria (greater than 150 mg/24 h and Albustix +). They were given perindopril 4 to 8 mg orally once daily, and received a stable diet. Diastolic blood pressure was normalized within the first 3 months in 80% of the patients. From these, 28 (14.7 and 7 from groups I, II and III respectively) were followed during a total active treatment period of 12 months. They were matched for age, duration of diabetes and hypertension, systolic and diastolic blood pressures, daily insulin dose, postprandial plasma C-peptide and quality of glycaemic control. Mean supine diastolic blood pressure was decreased by 15 and 18% at 1 and 12 months respectively. Heart rate was not significantly modified. At 3 months, plasma ACE activity was nearly totally inhibited while plasma renin activity was markedly increased. In patients of group II, microalbuminuria was reduced from 66 +/- 13 (mean +/- SEM after placebo) to 39 +/- 6 mg/24 h after 1 month perindopril and this effect was maintained at 12 months. In group I, albuminuria remained within the normal range. In group III, macroproteinuria was not consistently modified by perindopril. Creatinine clearance did not change and glycaemic control remained stable throughout the study in the 3 groups. No major side effects were observed. We conclude that perindopril normalizes blood pressure in a large majority of hypertensive diabetic patients without affecting the quality of diabetes control. It also induces a marked and sustained reduction of microalbuminuria in patients at risk of developing diabetic nephropathy.

Adult↗
PubMed1990

Moderate cold exposure shortens evoked potential latencies in humans.

Visual, auditory event-related potentials, and brainstem auditory-evoked responses were recorded in as many as six young male subjects in order to study the effects of moderate cold air exposure on central nervous system functioning. Evoked potentials were recorded during repeated 50-min exposures to air of 4 and 22 degrees C; these levels of exposure resulted in no change in rectal core temperature. Evoked potentials recorded during exposures to 4 degrees air displayed consistently shorter latencies compared to those recorded at 22 degrees, suggesting faster CNS processing of sensory stimuli in the cold. These results are consistent with recent investigations of cold-induced behavioral response changes which indicate that increased arousal may occur with moderate (nonhypothermic) cold exposure.

Adult↗
PubMed1989

Cell-type-specific and site-specific N-glycosylation of type I and type II human tissue plasminogen activator.

Tissue plasminogen activator (t-PA) is an important initiator of fibrinolysis. The t-PA polypeptide has four potential N-glycosylation sites of which three are occupied in type I (Asn-117, -184, and -448) and two in type II (Asn-117 and -448). In an effort to elucidate the factors controlling the expression of N-linked oligosaccharides on this polypeptide, we have used a combination of sequential exoglycosidase digestion, methylation analysis, and controlled acetolysis to determine the oligosaccharide structures at each of the N-glycosylation sites of type I and type II t-PA when isolated from a human colon fibroblast cell strain and from a Bowes melanoma cell line. Our results suggest the following: (i) type I and type II t-PA are N-glycosylated in an identical way at Asn-117 and Asn-448, when isolated from the same cell line; (ii) Asn-117 is predominantly associated with oligomannose-type structures in all cases; (iii) Asn-184 and Asn-448 are predominantly associated with complex-type structures when t-PA is isolated from fibroblast cells, but with both complex- and oligomannose-type structures when isolated from melanoma cells; (iv) fibroblast cell derived t-PA is associated with both neutral and sialylated oligosaccharides, while melanoma cell derived t-PA is also associated with sulfated oligosaccharides, which are located exclusively at Asn-448 of type II t-PA; (v) no complex-type structures occur in common between t-PA from the two cell lines. These results indicate that the t-PA glycoprotein is secreted by each cell line as a set of glycoforms, each glycoform being unique with respect to the nature and disposition of oligosaccharides on a common polypeptide. Further, the two cell lines express no glycoform in common, despite expressing the same t-PA polypeptide. The implications of these results for both the control of oligosaccharide processing in different cell lines and the genetic engineering of mammalian glycoproteins are discussed.

Amino Acids↗
PubMed1989

N-glycosylation and in vitro enzymatic activity of human recombinant tissue plasminogen activator expressed in Chinese hamster ovary cells and a murine cell line.

To probe the effects of N-glycosylation on the fibrin-dependent plasminogenolytic activity of tissue-type plasminogen activator (t-PA), we have expressed a human recombinant t-PA (rt-PA) gene in Chinese hamster ovary (CHO) cells and in a murine C127 cell line. The resulting rt-PA glycoproteins were isolated and their associated N-linked oligosaccharide structures determined by using a combination of high-resolution Bio-Gel P-4 gel filtration chromatography, sequential exoglycosidase digestion, and methylation analysis. The results show that CHO rt-PA is N-glycosylated differently from murine C127 derived rt-PA. Further, both rt-PA's are N-glycosylated differently from t-PA derived from a human colon fibroblast and the Bowes melanoma cell line (Parekh et al., 1989), confirming that N-glycosylation of the human t-PA polypeptide is cell-type-specific. Both CHO and murine rt-PA were fractionated on lysine-Sepharose chromatography. The N-glycosylation of the major forms was analyzed and their fibrin-dependent plasminogenolytic activity determined by using an indirect amidolytic assay with Glu-plasminogen and a chromogenic plasmin substrate. The results suggest that the various forms of rt-PA differ from one another with respect to the kinetics of their fibrin-dependent activation of plasminogen. Together, these data support the notion (Wittwer et al., 1989) that N-glycosylation influences the fibrin-dependent catalytic activity of t-PA and that t-PA when expressed in different cell lines may consist of kinetically and structurally distinct glycoforms.

Animals↗
PubMed1989

Effects of reduction in drugs or dosage after long-term control of systemic hypertension.

The possibility of discontinuing--compared to reducing--antihypertensive drug treatment was investigated in 606 male hypertensive patients with entry diastolic blood pressure (BP) in the range of 90 to 114 mm Hg. Diastolic BP was controlled at less than 90 mm Hg with 1 of 4 regimens: low dose hydrochlorothiazide (HCTZ), 25 mg twice daily; high dose HCTZ, 50 mg twice daily; or high dose HCTZ plus a low or high dose of a step II drug (propranolol, clonidine or reserpine). After 6 months of treatment that controlled BP, dosages were reduced in two-thirds of the patients. In those patients receiving low dose HCTZ and randomized to dose reduction, antihypertensive drugs were completely discontinued. Although approximately half of these patients remained normotensive for the first 6 months, a significantly greater proportion had elevation of BP compared to the control group, which continued to receive treatment (p less than 0.0001). In the high dose HCTZ drug group, the proportion of patients remaining normotensive did not differ among those stepped down to low dose HCTZ and the fully treated control group. While not achieving significance the trend was similar with the step II regimens. Although some patients remained normotensive after discontinuation of step II drugs, a greater proportion returned to elevated BP than when step II dosage was unchanged. Therefore, while stopping therapy may be effective in some patients, a decreased dosage is significantly more effective as a method for maintaining an antihypertensive effect. Decreasing drug dosages offers the dual benefit of minimizing side effects and reducing drug costs.

Antihypertensive Agents↗
PubMed1989

Clavicular division technique. A new approach for lengthening the pectoralis flap.

Complications associated with using the pectoralis major myocutaneous flap increase significantly when a portion of the paddle is randomized and/or the flap is closed under tension. The clavicular division technique was devised to increase the length of the flap to help alleviate this problem. Thirty pectoralis major muscle flaps were dissected in fresh cadavers, using the clavicular division technique. The length of the flap after transposition was measured and recorded before and after clavicular division. The distance from the sternal notch to the clavicular division point was also recorded. The average gain in length was found to be 2.9 cm, with a range of 0.5 cm to 6.5 cm. The clavicular division technique has been used since in five patients. The increase in length has allowed us to discard some or all of the random portion of the flap. We advocate the use of this procedure on any patient where the surgeon is concerned about the viability of the random portion of the flap and/or when it is felt that the tension on the suture line is excessive.

Clavicle↗
PubMed1989

Analysis of patient response to preoperative computerized video imaging.

Preoperative computer-assisted video imaging was performed on 50 consecutive rhinoplasty candidates, along with routine preoperative photographs and assessment. Each patient then completed a questionnaire dealing with the imaging process. Patient acceptance of the imaging process was excellent. Responses indicated that most patients felt that video imaging improved communication between patient and surgeon, increased patient confidence in surgery and surgeon, and enhanced the patient-physician relationship. The future use of computer-assisted video imaging in teaching, preoperative planning, and improved post-operative patient satisfaction is discussed.

Adult↗
PubMed1989

Use of injectable cultured human fibroblasts for percutaneous tissue implantation. An experimental study.

Large quantities of cultured human facial dermal fibroblasts were propagated from randomly selected patients to determine their relative suitability as percutaneously injectable living implants. Volumetric and histologic comparisons were made between the following implants that were injected subcutaneously into athymic nude mice: (1) cultured human fibroblasts (HFb); (2) cultured human fibroblasts dispersed in Zyderm II collagen (HFb + Zyd); (3) Zyderm II collagen (Zyd); and (4) Zyplast collagen (Zyp). Both the HFb and HFb + Zyd implants were accepted as primary takes but regressed volumetrically at significantly greater rates than either the Zyd or Zyp implants. Correlative immunohistochemical staining revealed that, by 10 days, 90% of the cells within the HFb implants and 80% within the HFb + Zyd implants were of human origin; however, by 9 weeks, approximately 25% of the cells were of human origin in both types of implants. These results indicated that cultured human fibroblasts can be successfully injected as living grafts; however, the subsequent gradual attrition in the numbers of implanted cells, as noted in this model system, limits the long-term retention of the implants.

Animals↗
PubMed1989

Intensity threshold for 60-Hz magnetically induced behavioral changes in rats.

Experiments were conducted to further investigate the effect of 60-Hz cyclotron-resonance exposures on rats performing on a multiple FR-DRL schedule. The previously reported temporary loss of DRL baseline response, when measured as a function of A.C. magnetic intensity, was found to have a threshold. Utilizing the component of A.C. magnetic intensity parallel to the D.C. field, we report this threshold as (0.27 +/- 0.10) x 10(-4) Trms.

Animals↗
PubMed1989

Longitudinal tibial epiphyseal bracket in Nievergelt syndrome.

A patient is described with lower extremity mesomelic dwarfism associated with bilateral congenital elbow, hip, and knee dislocations. Rhomboid-shaped tibiae and delayed ossification of the primary fibular ossification centers were demonstrated at birth. Plain films and magnetic resonance imaging revealed that the tibial deformities were due to the presence of longitudinal epiphyseal brackets. These brackets were observed at surgery and confirmed histologically. Recognition of the longitudinal epiphyseal bracket and its relationship to the tibial deformities seen in this patient with Nievergelt syndrome is important for planning surgical treatment.

Child, Preschool↗
PubMed1989

Relation of knowledge and performance in boys' tennis: age and expertise.

This research examined boys' development of knowledge structure and sport performance in tennis. To assess decision-making and performance, expert and novice tennis players (10-11 and 12-13 years old) were compared on tennis performance (control, decision, and execution), tennis knowledge, serve skill, and groundstroke skill. Experts regardless of age performed better than novices on tennis skill and knowledge; experts' decisions and actions were better during tennis game performance. Declarative knowledge was related to the development of procedural knowledge; serve and groundstroke skill were related to the motor execution components of performance. Interviews during and after game play were used to examine knowledge and decision-making. Experts, as compared to novices, focused on higher level concepts, had more connections between concepts, and had more condition and alternative action concepts that were important to the game's goal structure. Experts' greater decision-making ability during game play was related to their knowledge structure.

Age Factors↗
PubMed1989

Cancer of the perioral region.

The management of difficult perioral malignancies is often facilitated by an organized, multidisciplinary approach that utilizes the skills of a Mohs micrographic surgeon as well as a head and neck surgeon. This article summarizes such an approach with attention to anatomic considerations, tumor classification, prognosis, and a practical approach to such malignancies. Finally, an approach to reconstruction is presented that emphasizes the usefulness of a Karapandzic flap in large reconstructions of this region.

Carcinoma, Squamous Cell↗