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Biomedical subjects

D M Shah

Publications and source records attributed to D M Shah.

At least 181 records · Page 10Linked to original sources
PubMed1986

Reversal of opsonic deficiency in surgical, trauma, and burn patients by infusion of purified human plasma fibronectin. Correlation with experimental observations.

Plasma fibronectin deficiency has been documented in critically ill surgical, trauma, and burn patients. Human plasma fibronectin was isolated by gelatin-Sepharose affinity chromatography and evaluated with respect to its opsonic activity following pasteurization, its in vivo clearance kinetics, and its short-term influence on cardiovascular hemodynamics in postoperative septic sheep. Six patients with low plasma fibronectin levels were also evaluated with respect to temporal changes of immunoreactive fibronectin and opsonic activity following infusion of fibronectin at a dose calculated to elevate the plasma fibronectin level to 400 micrograms/ml. With utilization of three different in vitro radioisotopic phagocytic assays, i.e., liver slice assay, peritoneal macrophage monolayer assay, and Kupffer cell monolayer assay, retention of opsonic activity by fibronectin following pasteurization was documented. The normal biphasic kinetics associated with plasma clearance of fibronectin were also not altered by pasteurization. In postoperative septic sheep with hemodynamic instability, intravenous infusion of 500 mg of purified human fibronectin initiated no abnormal hemodynamic response. Indeed, as compared with placebo, the infusion of fibronectin into the postoperative septic sheep resulted in a more stable systemic vascular resistance and pulmonary vascular resistance with a higher arterial pressure. It also elevated immunoreactive fibronectin levels (p less than 0.05) and increased opsonic activity (p less than 0.05). Surgical, trauma, and burn patients (ages 18 to 80 years) with low plasma fibronectin levels (160 to 236 micrograms/ml) manifested no disturbance in cardiovascular, respiratory, or hematologic parameters following fibronectin infusion (590 to 988 mg per patient), but did display an early increase of opsonic activity. This standardized, pasteurized, and opsonically active preparation of purified human plasma fibronectin (5.0 mg/ml after reconstitution) has utility for future randomized clinical trials in injured patients with sepsis.

Adolescent↗
PubMed1986

Initial experience comparing B-mode imaging and venography of the saphenous vein before in situ bypass.

Preoperative saphenous vein assessment was performed using both venography and B-mode scanning. Fifty patients underwent preoperative assessment, and the results were compared with the intraoperative findings. Both venography and B-mode imaging were equally accurate at determining the dominant saphenous system, but B-mode imaging missed five thigh double systems that were shown on venography. Neither venography nor B-mode imaging were good predictors of actual vein size at most sites in the leg, with the exception of B-mode assessment below the knee, where there was a positive correlation with intraoperative vein size (r = 0.80; p less than 0.01). In our study, B-mode scanning was consistently more reliable in determining vein presence and continuity than venography, which gave nine false-negative results. Finally, B-mode imaging allows the marking of a saphenous vein map on the patient's leg preoperatively as a guide to bypass surgery.

Aged↗
PubMed1986

Hepatic macrophage complement receptor clearance function following injury.

Previous work has demonstrated that in vivo hepatic macrophage complement receptor clearance function is depressed following thermal injury. The present study was carried out to determine if complement receptor function depression is associated with other states of depressed host defense. Hepatic complement receptor clearance function was determined from the hepatic uptake of rat erythrocytes coated with antierythrocyte IgM (EIgM) in rats. Receptor function was determined following cannulation of a carotid artery, laparotomy plus enterotomy, hemorrhagic shock, trauma, thermal injury, acute bacteremia, acute endotoxemia, and injection of erythrocyte stroma, gelatinized lipid emulsion, or colloidal carbon. Hepatic uptake of EIgM was depressed following each of these experimental interventions except arterial cannulation. This effect was shown not to be due to a decrease in hepatic blood flow or depletion of complement and was therefore due to a depression in hepatic macrophage complement receptor clearance function. Thus, impairment of hepatic macrophage complement receptor function is associated with several states of depressed host defense.

Animals↗
PubMed1986

Transfemoral placement of intraluminal polyurethane prosthesis for abdominal aortic aneurysm.

Because of the significant mortality associated with the conventional surgical approach to abdominal aortic aneurysms (AAA) in the high risk patients and in those with ruptured aneurysms, we have developed a new approach to this problem, intraluminal aneurysm exclusion. This was achieved by an intraluminal prosthesis which approximated the diameter of the aorta above and below the aneurysm and is inserted through the femoral artery. The prosthesis consisted of biomedical grade elastomeric polyurethane with a NITINOL and/or stainless steel frame and was designed in such a configuration that it could be compressed inside a 15 F catheter and then regain its original shape after being discharged inside the aorta. The polyurethane prosthesis tolerated static pressures in excess of 300 Torr. Aneurysmal aortas were created in three adult sheep using large knitted Dacron pathches (6 X 9 cm) sewn onto a longitudinal aortotomy. After 4-6 weeks, an intraluminal prosthesis was passed transfemorally to the location of the aortic aneurysm. Following satisfactory placement and expansion of the prosthesis, a laceration was produced in the aneurysmal wall. No bleeding developed, which confirmed the integrity of the prosthesis in excluding the aneurysm from the aorta proper. Pulsation in the iliac arteries indicated the presence of aortic blood flow through the prosthesis. Autopsy examination demonstrated directly that the prosthesis was open and that its two ends were fixed in the aorta above and below the aneurysm. The study has demonstrated that intraluminal AAA exclusion could be achieved with an intraluminal polyurethane prosthesis inserted through the femoral artery.

Animals↗
PubMed1986

Transabdominal and transvaginal endosonography: evaluation of the cervix and lower uterine segment in pregnancy.

The clinical value of conventional transabdominal and transvaginal sonography (endosonography) for the evaluation of the cervix and lower uterine segment between 14 and 36 weeks' gestation was evaluated in 20 unselected obstetric patients. Sonographic evaluation of the cervix and lower uterine segment was adequately depicted in 76% with the transabdominal technique compared to 83% with the transvaginal approach. According to set guidelines, these preliminary results suggest that the transvaginal technique may be superior in obtaining an adequate evaluation of the lower uterine segment and cervix and may offer an advantage of not depending on a fully distended bladder for evaluation.

Abdomen↗
PubMed1986

Effects of isovolemic hemodilution on abdominal aortic aneurysmectomy in high risk patients.

Intraoperative isovolemic hemodilution might increase blood flow and tissue oxygenation in the periphery but there is concern that acute anemia may have deleterious effects on myocardium in patients with coronary artery disease. This study investigates the effects of intraoperative isovolemic hemodilution on morbidity, mortality and hemodynamics in 32 patients with significant cardiovascular disease undergoing elective abdominal aortic aneurysmectomy. The average hematocrit was lowered intraoperatively from 43% to 31% by withdrawing blood and replacing volumes with 1:3 Ringer's lactate. In ten patients myocardial function was evaluated during aortic cross-clamping and declamping in the face of hemodilution. There were two deaths: one myocardial infarction and one multiple organ failure. Aortic cross clamping did not change heart rate, vascular pressures (VP), vascular resistance (SVR), cardiac output (CO), and left ventricular stroke work (LVSW). Following declamping, VP, CO and LVSW decreased and SVR increased momentarily (p less than 0.05), but the myocardial function did not change. Isovolemic hemodilution had no apparent adverse effects on morbidity, mortality and cardiovascular performance in these patients.

Aged↗
PubMed1986

Translocation of the precursor of 5-enolpyruvylshikimate-3-phosphate synthase into chloroplasts of higher plants in vitro.

5-enolPyruvylshikimate-3-phosphate synthase (EPSP synthase; 3-phosphoshikimate 1-carboxyvinyl-transferase; EC 2.5.1.19) is a chloroplast-localized enzyme of the shikimate pathway in plants. This enzyme is the target for the nonselective herbicide glyphosate (N-phosphonomethylglycine). We have previously isolated a full-length cDNA clone of EPSP synthase from Petunia hybrida. DNA sequence analysis suggested that the enzyme is synthesized as a cytosolic precursor (pre-EPSP synthase) with an amino-terminal transit peptide. Based on the known amino terminus of the mature enzyme, and the 5' open reading frame of the cDNA, the transit peptide of pre-EPSP synthase would be maximally 72 amino acids long. To confirm this prediction and to assay directly for translocation of pre-EPSP synthase into chloroplasts in vitro, we cloned the full-length cDNA into an SP6 transcription system to produce large amounts of mRNA for in vitro translation. The translation products, when analyzed by NaDodSO(4)/PAGE autoradiography, indicate a relative molecular mass for pre-EPSP synthase of approximately 55 kDa. Uptake studies with intact chloroplasts, in vitro, indicate that pre-EPSP synthase was rapidly taken up into chloroplasts and proteolytically cleaved to the mature approximately 48-kDa enzyme. The transit peptide was shown to be essential for import of the precursor enzyme into the chloroplast. To our knowledge, post-translational import into chloroplasts of a precursor enzyme involved in amino acid biosynthesis has not been reported previously. Furthermore, enzymatic analysis of translation products indicates that pre-EPSP synthase is catalytically active and has a similar sensitivity to the herbicide glyphosate as the mature enzyme. To our knowledge, pre-EPSP synthase represents the only example of a catalytically competent chloroplast-precursor enzyme.

Journal Article↗
PubMed1986

Transcutaneous flow measurements in in-situ bypasses: an assessment of duplex scanning.

Measurement of laminar flow using an ultrasound scanner was shown to have a high degree of correlation with quantified timed flows (r = 0.98, p less than or equal to .001). Sixty-one in-situ bypasses had flow assessed both proximally and distally. Mean fistula flow (proximal-distal flows) for time periods 1-8 weeks, 3 to 8, and 9+ months were 108, 85, and 16mls respectively. Distal bypass flow remained constant despite a significant decrease in fistula flow between the later time periods (p less than or equal to .001) (unpaired t-test). There was no evidence from the study that proximal flow through fistulas of varying resistances adversely affected the distal bypass flow.

Arteriovenous Fistula↗
PubMed1986

Distal in situ vein bypass torsion--a technique to avoid it.

One of the stated advantages of the in situ bypass is that twists or torsion along the vein are automatically prevented by the technique. Unfortunately, this is not strictly true because the distal mobilized end of the vein, which is being anastomosed to the outflow tract, is quite prone to twists of 180 to 360 degrees after its arterialization. This torsion may result in either immediate cessation of flow or later formation of an anastomotic stenosis. We describe a technique that, when used, should eliminate all such problems.

Humans↗
PubMed1986

Perioperative hypertension in patients undergoing carotid endarterectomy: shorter duration under regional block anesthesia.

Two alternative anesthetic techniques for use during carotid endarterectomy were studied in a series of 424 procedures. A total of 248 were performed in patients under general anesthesia and 176 patients received regional block anesthesia. Perioperative instability of blood pressure was noted in 108 patients. Hypertension was noted in 17.7% of those under general anesthesia vs 20.5% of those under regional block anesthesia. Intravenous vasodilator agents were used for 19.62 hr (+/- 4.33) in the general anesthesia group vs 1.4 hr (+/- 0.44) in the regional block anesthesia group (p less than .02). Perioperative hypertension correlated best with uncontrolled preoperative hypertension. Under regional block anesthesia the incidence of shunting was 4.5%. The 1 month operative mortality for the entire carotid series was 1.2% (5/424). There were three stroke-related deaths. In addition, two nonfatal major strokes and two minor strokes occurred in patients who received general anesthesia vs one nonfatal major stroke in a patient who received regional block anesthesia.

Aged↗
PubMed1986

Visceral aortic aneurysm in a 4 1/2-year-old child: an unusual complication of umbilical artery catheterization.

A 4 1/2-year-old girl had a 2.2 cm in diameter abdominal aortic pseudoaneurysm extending from above the celiac artery to 4 cm above the aortic bifurcation. This lesion developed after umbilical artery catheterization in the neonatal period, which also resulted in thrombosis of the right renal artery and renal atrophy. Patch graft angioplasty with polytetrafluoroethylene (Gore-Tex) was performed after excision of the aneurysm via a retroperitoneal approach.

Aorta, Abdominal↗
PubMed1986

The anatomy of the greater saphenous venous system.

To define surgical anatomy, a prospective study of the greater saphenous venous system in 385 instances in 331 patients was carried out with the use of prebypass phlebography (either pre- or intraoperative). The phlebographic interpretations were confirmed during the operative procedures and from the completion angiogram. These details were recorded and analyzed by a specific computer program. These data consisted of a number of superficial branches, perforators, the identification of valve leaflets, sinuses, and the size and position of the main venous trunk both in the thigh and in the calf. The study showed that a single trunk was present in the thigh in 65% of patients and in the calf in 45%. The remainder were variants of double systems. In two thirds of patients who had complete double systems, the larger system was used for in situ bypass but the rest required the use of parts of both systems. Phlebography was accurate in the depiction of the anatomic variations (93%), double systems, cross connections, and perforator branches (87%). However, the number of competent valves could not be accurately determined (accuracy, 68%). The diameter of the vein was frequently underestimated (in 80% by 1.1 +/- 0.4 mm) and hence could not be used as an index of vein adequacy. After phlebography, four patients had transient rises in serum creatinine levels and one had an iatrogenic thrombosis of a distal segment. This study suggests that the precise anatomy of the greater saphenous venous system should be determined preoperatively by phlebography since this information is valuable for proper surgical planning before vein is used as a graft or for in situ bypass in the lower extremity.

Adult↗
PubMed1986

Improved outcome of twice weekly nonstress testing.

The nonstress test is a commonly used tool for fetal well-being assessment. The antenatal death rate using the nonstress test as a primary modality is significantly higher than that with the use of the contraction stress test. The nonstress test is commonly performed on a once-a-week basis. The rate of stillbirths with reactive nonstress tests, performed once a week, was 6.1 per 1000 in the author's previously published report. Nonstress tests were performed on a twice-a-week basis beginning January 1981, and results are reported on 913 such patients. The rate of stillbirths with reactive nonstress tests was reduced to 1.9 per 1000 in this second group. It is suggested that the patients who are at risk for fetal stress should be evaluated on a twice-a-week basis when the nonstress test is used as the primary test.

Female↗
PubMed1985

Relationship between vasa vasorum and blood flow to vein bypass endothelial morphology.

In order to define the respective roles of the vasa vasorum blood supply and intraluminal arterial blood flow in maintaining the endothelial integrity of in situ vein bypasses, we have carried out two separate but interrelated experiments in a canine model. In vivo studies on eight dogs demonstrated that even in the absence of intraluminal blood flow the vasa vasorum maintained endothelial integrity and also showed that the endothelium was very sensitive to the loss of the vasa vasorum blood supply. In a second group of experiments on 14 in situ vein bypasses we studied the effect of division of the vasa vasorum immediately after arterialization of the bypass. This experiment showed that arterialization of the vein maintained endothelial integrity despite division of the vasa vasorum.

Animals↗
PubMed1985

High-level expression of the bovine growth hormone gene in heterologous mammalian cells.

The gene coding for bovine growth hormone (bGH) was isolated from a lambda-phage library constructed using bovine pituitary DNA partially digested with MboI. Expression of this gene transfected into mouse and monkey cells was studied. CV-1 monkey cells transfected with simian virus 40 (SV40) vectors containing the intact bGH gene, including the putative promoter region, did not express bGH. However, replacement of the bGH promoter with the mouse metallothionein-I (MT) promoter resulted in high-level synthesis and secretion of bGH. These results show that the bGH promoter functions poorly in CV-1 cells but CV-1 cells process and translate the bGH mRNA accurately. The MT-bGH chimeric gene was used to establish permanent bGH-secreting mouse C127 cell lines using the 69% transforming fragment of bovine papilloma virus (BPV) as the vector. One such cell line produced high levels of bGH and secreted it into the medium efficiently. Secreted bGH is processed accurately and is bioactive as judged by its ability to bind to rabbit liver membrane preparations.

Animals↗
PubMed1985

Complication of insulin-dependent diabetic pregnancies by preeclampsia and/or chronic hypertension: analysis of outcome.

The significance of hypertensive complications of insulin-dependent diabetic pregnancies (IDDP) has not been well examined since the early reports of Pedersen, which demonstrated an increased risk of neonatal death in women with pregnancy induced hypertension (PIH). To assess the effect of both PIH and chronic hypertension (CH) on outcome of IDDP managed using contemporary obstetrical and diabetic management, we reviewed the records of all 199 IDDP delivered at our institution over a 7-year period. Patients were classified as having PIH (Group 1, n = 37), CH (Group 2, n = 18) or both (Group 3, n = 4) on the basis of standard clinical criteria. All other IDDP were placed in the control group (Group 4, n = 140). Comparing all groups, significant differences were found for maternal age (P less than .0001) and distribution among White's Classes (P less than .0001). There was no significant difference in estimated gestational age (EGA) at delivery, birthweight, Apgar scores, hypoglycemia, hyperbilirubinemia, or congenital anomalies. Intrauterine fetal death (IUFD) was no more common in Groups 1, 2 or 3 than in Group 4; however, IDDP with CH were significantly more likely to have had previous stillbirths than IDDP with PIH (P = .011) or control IDDP (P = .017). Contrary to common clinical belief, the "stress" of CH and PIH did not offer protection to the newborn in the development of RDS or HMD. In fact, Group 3 infants had a higher rate of HMD than control infants (P = .024).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1985

Advances in the management of acute popliteal vascular blunt injuries.

This report evaluates critical points in the management of 30 consecutive blunt traumatic popliteal vascular injuries. All arterial injuries were diagnosed both clinically and by Doppler and PVR examinations. Twenty-eight of the 30 arterial reconstructions required interposition bypass grafts, nine of which were PTFE and the remainder were autogenous saphenous veins. In 19 patients the distal anastomosis was made to the distal popliteal artery and in nine patients to the tibial-peroneal arteries. In ten patients in whom limb survival was threatened, the ischemic time was shortened by the use of temporary Silastic shunt for rapid restoration of arterial flow. Nine patients had associated venous injuries which were repaired. Nine of the first 14 patients required fasciotomy but the last 16 patients were treated with hypertonic mannitol and only two of them required fasciotomy. There were no amputations, but in four limbs there were functional losses. In spite of the more extensive damage of blunt trauma, prompt and aggressive management aided by vascular laboratory tests, indwelling shunt, and hypertonic mannitol is rewarded with preservation of limbs following acute popliteal vascular injuries.

Adolescent↗