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Biomedical subjects

J G Wright

Publications and source records attributed to J G Wright.

At least 145 records · Page 8Linked to original sources
PubMed1992

Effect of prone versus supine patient positioning on pelvic magnetic resonance image quality.

RATIONALE AND OBJECTIVES: Magnetic resonance imaging (MRI) of the pelvis in the prone position has been proposed as a means of reducing motion-related image blurring. The authors performed a randomized controlled trial to determine if patient positioning affects image quality. METHODS: All women undergoing pelvic MRI during a 7-month period, who could lie both prone and supine, were randomized to the supine or prone position. The quality of axial T2-weighted spin-echo images was rated by two radiologists using a 1-to-4 scale (1 = marked blurring to 4 = sharp definition of pelvic structures). RESULTS: Of 78 eligible women, 61 were randomized. Two patients could not complete the examination. The mean image quality rating of 2.8 for the 32 patients imaged prone was not significantly different from the mean rating of 2.9 for the 27 patients imaged supine (P = .5, Mann-Whitney U test). CONCLUSION: Patient positioning did not significantly affect pelvic MRI quality. The choice of patient position should be based on other considerations, such as patient comfort or ease of patient positioning.

Adult↗
PubMed1992

Severe thrombocytopenia secondary to asymptomatic cytomegalovirus infection in an immunocompetent host.

A healthy 33 year old man presented with a short history of purpura and easy bruising. Investigations showed profound thrombocytopenia with atypical lymphocytes in the peripheral blood. Marrow appearances were consistent with platelet consumption. Biochemical hepatitis was also noted. An infection screen showed the underlying diagnosis to be cytomegalovirus (CMV) infection. He was treated successfully with oral prednisolone. This subsequently tailed off without relapse. Careful examination of a stained blood film is needed in all cases of apparent idiopathic immune thrombocytopenic purpura.

Adult↗
PubMed1992

Why do most surgical incisions require lengthening? How to avoid it.

When an incision is retracted, it shortens because skin does not actually stretch--it only shifts. A mathematical model accurately predicted operating room experience. Average retraction of 30-50% shortens an incision by 15%. Therefore, an incision to expose fixed bony landmarks should be 15% longer than the distance between them.

Humans↗
PubMed1991

Mechanisms of glove tears and sharp injuries among surgical personnel.

OBJECTIVE: --The development of strategies to prevent exposure to blood for operating room personnel has been hampered by a lack of knowledge about the specific mechanisms of exposure. The purpose of this study was to classify the mechanisms of glove tears and sharp injuries in the operating room. DESIGN: --During a 3-month period, a nurse interviewed operating room personnel immediately after a glove tear or sharp injury had occurred. SETTING: --Yale-New Haven (Conn) Hospital is a tertiary care teaching hospital. RESULTS: --There were 249 glove tears and 70 sharp injuries. Visible skin contact with the patient's blood occurred in 156 glove tears (63%). The mechanism causing the tear could be identified in only 81 (33%). For 230 glove tears (92%), personnel were wearing single gloves. Of 70 sharp injuries, 47 (67%) were caused by needles and usually occurred during suturing. The following three mechanisms accounted for 40 sharp injuries (57%): (1) hands injured while stationary and holding an instrument, 11 (16%)-a position of risk not previously identified; (2) hands injured while retracting tissue, 12 (17%); and (3) injuries caused by sharp instruments not being used, 17 (24%). Instrument passage caused only four sharp injuries (6%). CONCLUSIONS: --The majority of glove tears have an unknown mechanism, and alteration in the manufacture or number of gloves worn may be helpful in reducing cutaneous blood exposures. The identification of specific mechanisms of sharp injuries should lead to effective strategies to prevent exposure to the human immunodeficiency virus and other blood-borne pathogens in the operating room.

Accidents, Occupational↗
PubMed1991

Hepatorenal and splenorenal artery bypass for salvage of renal function.

Hepatic and splenic arteries have been used increasingly as inflow sources to avoid aortorenal bypass in patients whose cardiac dysfunction may be exacerbated by aortic clamping and in patients with previous aortic grafting in whom periaortic dissection is more hazardous than incising undisturbed tissue planes. During an 18-month period, eight patients with atherosclerotic renal artery stenosis and azotemia were treated with six hepatorenal and five splenorenal artery bypasses. Serum creatinine improved initially in all patients. Severe hypertension, present in five patients, improved significantly in four (80%). In one-half the gastroduodenal branch of the hepatic artery was suitable for end-to-end anastomosis to the renal artery, obviating the need for an interposition graft. Hepatorenal bypass is a safe, simple procedure that has been associated with few complications, although occasional transient subclinical evidence of hepatic dysfunction has been reported. Splenorenal bypass requires a relatively more hazardous exposure and is associated with a low risk of splenic and pancreatic injury, especially when the spleen and splenic flexure of the colon are mobilized to expose the splenic artery. The risk of splenic injury is substantially reduced when the splenic artery is approached through the retroperitoneum at the base of the transverse mesocolon as described.

Anastomosis, Surgical↗
PubMed1991

Safety of simultaneous aortic reconstruction and renal transplantation.

Patients with aortic disease and end-stage renal failure who require both aortic reconstruction and renal transplantation (simultaneously or staged) pose a formidable clinical challenge. Traditionally, the performance of either one of these procedures has been viewed as a relative contraindication to the performance of the other. From 1978 to 1989, eight patients were referred to us with the combination of aortic disease and end-stage renal failure. Seven had aneurysmal disease and one had aorto-iliac occlusive disease. Five patients presented with their diseases sequentially and had two sequential operations, with a mean interval of 4 years between procedures. Three patients presented with their diseases simultaneously and underwent simultaneous aortic reconstruction and living related renal transplantation. All patients were followed up for a mean interval of 4.5 years. By life-table analysis, the 5-year renal graft survival was 100%, the primary aortic graft patency was 82%, and the secondary aortic graft patency was 100%. The only death in this series occurred 11 years after aortic reconstruction and 4 months after a renal transplantation and was due to overwhelming cytomegalovirus sepsis. There were no significant differences between the simultaneous and staged groups in terms of operative mortality, postoperative complications, transplant function, or aortic graft patency. From this experience, we conclude that: (1) patients who present simultaneously with aortic disease and end-stage renal failure can safely undergo simultaneous aortic reconstruction and renal transplantation; (2) patients who present with these two diseases sequentially can undergo a second reconstructive procedure with very low operative morbidity and mortality rates; (3) when these two procedures have been performed sequentially, the second procedure has not significantly altered the 30-day or 5-year results of the first procedure; and (4) the 30-day and 5-year results of each procedure have been excellent regardless of the temporal sequence in which they were performed.

Adult↗
PubMed1991

Impact of magnetic resonance imaging on the management of diabetic foot infections.

This combined retrospective/prospective study evaluated the value of magnetic resonance imaging (MRI) in 18 diabetic patients with apparent foot infections. The goal was to define the impact of MRI on directing the expedient and accurate surgical intervention so important in achieving optimal preservation of limb tissue and function. We found that MRI provides a rapid and reliable means of "viewing" the diabetic foot. Unsuspected or poorly localized abscess cavities can be pinpointed for thorough drainage with minimal exploration. An abscess can be differentiated from cellulitis or osteomyelitis. Moreover, persistent fever following drainage of a foot abscess can be reliably evaluated via MRI, obviating the need for empiric surgical reexploration. This exciting noninvasive imaging technique leads to the most accurate surgical drainage of foot abscesses and, at the same time, can prevent unnecessary surgical exploration of the tenuous diabetic foot.

Abscess↗
PubMed1991

Measurement of lower limb alignment using long radiographs.

Long radiographs are used to measure lower limb axial alignment, to assess the progression of deformity, and to plan corrective surgery. The purpose of this study was to test the belief that jigs are necessary in order to control limb position for radiography. Above-knee amputated limbs were fixed in different positions of rotation and of knee flexion and radiographed to study the effect on the apparent alignment of the limb. If the limb was rotated no more than 10 degrees from the neutral the effect on apparent axial alignment was minimal and radiographic measurement was reliable. This suggests that standardised positioning jigs are not needed in routine clinical practice.

Femur↗
PubMed1990

Iloprost infusion decreases skeletal muscle ischemia-reperfusion injury.

Iloprost (a long-acting prostacyclin analog) has been demonstrated to decrease cardiac muscle infarct size after ischemia-reperfusion injury. We investigated the ability of iloprost to decrease skeletal muscle injury and platelet sequestration after ischemia-reperfusion injury in a canine bilateral isolated gracilis muscle model. Anesthesized animals (n = 13) were subjected to 6 hours of gracilis muscle ischemia and 1 hour of reperfusion. Fifteen minutes before muscle reperfusion, the animals were infused with radium 111-labeled autogenous platelets. Experimental animals (n = 7) received a continuous preischemic intravenous infusion of iloprost (0.45 microgram/kg/hr) and two 0.45 microgram/kg intravenous injections of iloprost (10 minutes before the ischemic interval and 10 minutes before reperfusion). Muscle injury was measured with triphenyltetrazolium chloride histochemical staining. Platelet sequestration within ischemic muscle specimens was determined by measuring indium 111 activity in a gamma counter. Iloprost infusion decreased muscle infarct size from 57.0% +/- 12.6% in control animals to 15.8% +/- 4.4% in experimental animals (p less than 0.05). Platelet uptake in experimental and control muscle was 1.2 +/- 0.21 x 10(7) and 2.17 +/- 0.48 x 10(7) platelets/gm ischemic muscle, respectively (p = 0.1). Although platelet sequestration was not altered significantly in this experiment, a reduction in skeletal muscle injury was confirmed. Further investigation on the mechanisms of action of iloprost in chronic and acute skeletal muscle ischemia is warranted.

Animals↗
PubMed1989

The MerR heavy metal receptor mediates positive activation in a topologically novel transcription complex.

Several physical and chemical signals from the extracellular environment are known to be transduced into changes in gene expression through multiple step pathways; however, mechanisms for triggering cellular responses to heavy metal stress have yet to be elucidated. We demonstrate here one such mechanism that employs a single heavy metal receptor protein, MerR, to directly activate transcription of the bacterial mercuric ion resistance operon. The mercuric ion-MerR complex and E. coli RNA polymerase holoenzyme synergistically bind to the metal responsive promoter in an unprecedented spatial relationship to form transcriptionally competent complexes. The activator binds adjacent to and overlaps with the polymerase molecule between the consensus -35 and -10 promoter regions. Our results support a model for transcriptional activation that includes both effector-induced protein-protein interactions and activator-induced alteration in DNA structure.

Allosteric Regulation↗
PubMed1989

Postischemic hypothermia diminishes skeletal muscle reperfusion edema.

The mechanisms of ischemia-reperfusion injury in skeletal muscle remain controversial. We investigated the ability of postischemic hypothermia to diminish reperfusion edema and improve skeletal muscle pH in a bilateral, in vivo isolated canine gracilis muscle model. In five anesthetized animals, both gracilis muscles were subjected to 6 hr of ischemia followed by 1 hr of reperfusion. After 5 hr of warm ischemia, one gracilis muscle was cooled to 21 degrees C (cold reperfusion, CR) while the contralateral gracilis muscle was maintained at ambient temperature (warm reperfusion, WR). Reperfusion muscle edema was quantitated by measurement of gracilis muscle weight gain. Interstitial muscle pH was monitored by glass microelectrodes. Vascular permeability was measured by analysis of albumin (125I-Alb) leak. Results are presented as the means +/- SEM. (table; see text) Postischemic hypothermia significantly increased the interstitial muscle pH and significantly reduced postreperfusion muscle edema, without changing the vascular permeability to albumin. These data suggest that hypothermia may provide a clinical method for salvaging ischemic skeletal muscle from the postreperfusion edema that can lead to compartment syndromes, reperfusion injury, and subsequent limb loss.

Animals↗
PubMed1989

Cavopulmonary anastomosis as long-term palliation for patients with tricuspid atresia.

Prior to 1970, most patients with tricuspid atresia (TA) and reduced pulmonary blood flow were palliated by means of a systemic to pulmonary artery shunt (SPAS). In Birmingham between 1967 and 1988, 19 patients with TA (aged 16 days to 23 years, mean 3.8 years) have undergone side-to-side cavopulmonary anastomosis (CPA) with preservation of pulmonary artery continuity. One had undergone a previous right Blalock-Taussig shunt and in 1 patient with left and right SVCs, bilateral CPAs were performed. Nine patients were less than 1 year old at the time of operation. There were no operative deaths. One late death occurred due to pneumonia. Immediate clinical improvement occurred in all cases. Six symptomatic patients subsequently required further surgery (mean interval between operations 8.9 years, range 4.6-14.2 years). The remaining 12 patients have recently been reviewed. Mean follow-up was 9.5 years (range 5 weeks to 21 years). Exercise tolerance remains good (9 in NY-HA Class 1 or 2) and resting transcutaneous oxygen saturations are higher (mean 85%, range 70%-89%) compared with preoperative values (P less than 0.01). In small children, CPA avoids the complications of SPAS and, in some patients, may itself achieve adequate long-term definitive palliation.

Adolescent↗
PubMed1989

The role of leukocytes in the pathophysiology of skeletal muscle ischemic injury.

Neutrophilic leukocytes have been implicated as important mediators of ischemic myocardial injury. We investigated the role of neutrophils in skeletal muscle ischemia/reperfusion injury by using the rat hindlimb ischemia model. We rendered Wistar rats neutropenic by administering 750 rad of whole-body radiation (mean white blood cell count, 300 +/- 50/mm3; 3 days after radiation). In anesthetized rats (10 neutropenic and 10 control), 3 hours of ischemia were induced in one hindlimb by application of a tourniquet to the proximal thigh; the contralateral limb served as an internal, nonischemic control. After 1 hour of reperfusion the gastrocnemius and soleus muscles were excised bilaterally and evaluated for ischemic injury by means of a quantitative spectrophotometric assay of triphenyltetrazolium chloride (TTC) reduction. In control rats the reduction of TTC by ischemic muscle averaged 27.0% +/- 7.3% of that by nonischemic muscle; whereas in neutropenic rats the value for ischemic muscle was 65.4 +/- 11.6% (p less than 0.05). To determine if the contribution of the neutrophils to ischemic injury is due to oxygen-derived free radical formation, an additional 10 animals were infused with 5000 units of super-oxide dismutase and 10,000 units of catalase at the time reperfusion was restored. After treatment with free radical scavengers, TTC reduction by ischemic limbs was 25.5% +/- 7.0% of that by nonischemic limbs and did not differ from that in control animals (p greater than 0.05). The results show a protective effect of neutropenia and suggest a significant role of the white cell in the pathophysiology of ischemic skeletal muscle injury.

Animals↗
PubMed1989

The 'occult' compartment syndrome.

Two cases of compartment syndromes after tibial fractures are presented in patients who had no sensation in the involved compartments. The absence of any clinical symptoms in these patients emphasizes the need for routine monitoring of intra-compartmental pressure in this select group of patients.

Adult↗