Biomedical subjects

D M Shah

Publications and source records attributed to D M Shah.

At least 127 records · Page 7Linked to original sources

PubMed1990

Benefits of intra-abdominal pack placement for the management of nonmechanical hemorrhage.

Massive nonmechanical bleeding following severe liver injury is a difficult problem. Placement of intra-abdominal packs tamponades this nonmechanical bleeding and allows time for correction of various metabolic disturbances (ie, hypothermia, hypotension, acidosis, and coagulopathy). The purpose of this retrospective study was to evaluate the severity of these metabolic disturbances at the time of pack placement and the sequential improvement. It was found that most life-threatening disturbances that developed during the initial operative procedure could be corrected within 18 hours after pack placement and aggressive resuscitation. We concluded that the onset of nonmechanical bleeding and a coagulopathy marks a grave prognosis for the patient, and consideration should be given at this time for pack placement. Patients can then be aggressively resuscitated and returned to the operating room within 24 hours for pack removal if stability is achieved.

Acidosis↗

PubMed1990

Counseling and decision dilemmas associated with fetal blood sampling.

Counseling before fetal blood sampling via cordocentesis is more difficult than that done before amniocentesis because 1) a fetal anomaly has been detected or is very likely, 2) the cordocentesis procedure may have a higher risk than does amniocentesis, and 3) the gestational age is frequently advanced before referral. These factors result in counseling and decision dilemmas that include that 1) the advanced gestational age may preclude the option of termination, 2) fetal prognosis may be poor despite normal cytogenetic results, and 3) the benefit of a diagnosis to provide indications for various delivery options must be weighed against the psychological burden of documenting a chromosome abnormality far in advance of delivery. Thus, counseling before cordocentesis requires engaging the couple in decision making regarding potential management of the pregnancy as a prerequisite to choosing or declining the procedure.

Adult↗

PubMed1990

Comparison of the expression of two highly homologous members of the soybean ribulose-1,5-bisphosphate carboxylase small subunit gene family.

Two soybean ribulose-1,5-bisphosphate carboxylase small subunit (SSU) genes, SRS1 and SRS4, are highly homologous over a region that includes 4 kb of 5' and 1 kb of 3' flanking sequences. The expression of these genes was compared using synthetic oligonucleotide probes. Analysis of a soybean leaf cDNA library indicates that SRS1 and SRS4 are the most highly expressed members of the soybean SSU gene family. Similar changes were observed in the RNA levels for these genes in response to white light, far-red light and darkness, although SRS1 was expressed at a four-fold higher level in total RNA than SRS4 under all conditions. However, nuclear run-on assays indicate that SRS1 is transcribed at a lower rate than SRS4, which suggests that SRS1 RNA is more stable. S1 nuclease analysis and oligonucleotide directed RNase H cleavage indicate that transcripts from both genes are polyadenylated within two principle regions separated by 35 nt. Sequence analysis of 16 independent cDNA clones identified seven different polyadenylation sites, and six of these sites lie within these two regions. Although SRS1 RNA was poorly recovered during poly(A)+ fractionation, RNase H cleavage experiments showed that transcripts from SRS1 and SRS4 had similar poly (A) tail lengths ranging from 0 to 220 nt. In addition, and despite differences in the untranslated leader sequences, SRS1 and SRS4 RNAs are assembled into polysomes with equal efficiencies. The overall similarity in expression patterns for these two genes further illustrates the coordinate evolution of individual members of a SSU gene family and is consistent with the proposal that gene conversion homogenizes both the coding and regulatory regions of these genes.

Base Sequence↗

PubMed1990

Impact of the presence of orthopedic hardware on technical performance of major amputations.

Metallic prostheses used for joint reconstruction or open reduction of fractures were discovered pre- or intraoperatively during the performance of six above-knee amputations. The prosthesis was found fortuitously before surgery in two cases on the basis of a surgical scar or radiograph of the leg. In four patients, discovery occurred intraoperatively, with adverse impact on the procedure in two cases: more proximal amputation level to allow hip nail removal was necessary in one case, and difficult transection of the prosthesis stem was encountered in one case. Orthopedic prostheses will be found with an increasing incidence in the population undergoing major amputation. As preparation for amputation, a careful review of the patient's history, a search for scars over the leg and hip, and survey radiographs of the leg must be obtained to prevent a surgical mishap caused by accidental discovery of a prosthesis.

Amputation, Surgical↗

PubMed1990

The role of extraanatomic exclusion bypass in the treatment of disseminated atheroembolism syndrome.

We treated six patients with disseminated atheroembolism complicated by severe and unremitting pain from bilateral foot lesions. All patients had multiple and severe medical risk factors. One patient had a recent myocardial infarction, six patients had renal failure, and three were undergoing hemodialysis. Definitive aortic reconstruction was therefore precluded. After failing a course of medical therapy, each patient was treated with axillobifemoral bypass with exclusion-ligation of the external iliac arteries. Healing of foot wounds occurred in 11 of 12 limbs at risk, with one below-knee amputation required for progressive forefoot necrosis. In 12 patients with severe cardiopulmonary disease and limited life expectancy, exclusion-ligation bypass is an effective and safe palliative procedure for severe disseminated atheroembolism.

Aged↗

PubMed1990

Cordocentesis for rapid karyotyping.

Pure fetal blood was obtained by cordocentesis in 101 fetuses of 96 patients at 15 to 38 weeks' gestation. Rapid karyotype was obtained within 2 to 4 days by fetal lymphocyte culture. Chromosomal abnormality was detected in 12 (11.9%) fetuses. Abnormal karyotype was found in 5 of 44 fetuses with structural malformations, 3 of 13 fetuses with intrauterine growth retardation or oligohydramnios, 1 of 3 fetuses with nonimmune hydrops fetalis, 2 (one monozygotic set) of 10 discordant twins, 1 of 12 isoimmunized gestations, none of 8 cases with advanced gestational-maternal age, and none of 6 immune thrombocytopenia cases. This suggests that rapid karyotype should be obtained in all cases of fetal structural malformations, intrauterine growth retardation, and nonimmune fetal hydrops, and may be obtained incidentally in isoimmunized pregnancies and discordant twins to assist in clinical management.

Adult↗

PubMed1990

Antibiotic therapy for arterial infection: lessons from the successful treatment of a mycotic femoral artery aneurysm without surgical reconstruction.

A mycotic femoral artery aneurysm developed in a diabetic man with bacteremia from a Staphylococcus aureus urinary tract infection. Because of severe concomitant congestive heart failure and hypothyroidism, surgical reconstruction of the femoral artery was deferred while the patient received an intensive course of intravenous nafcillin. This led to stabilization of the size of the femoral aneurysm for two years, during which time it remained asymptomatic. Three such cases of nonsurgical treatment of a mycotic aneurysm have been documented. Surgical ligation, drainage, and bypass remain the mainstay therapies for mycotic aneurysms, but these cases demonstrate the possibility of sterilizing a primary arterial infection under the highly selected circumstances of an exquisitely sensitive organism, absence of periarterial abscess and readily observable anatomic location. Most importantly, these cases provide assurance that a six-week course of parenteral antibiotics is a reasonable adjunctive treatment for residual endovascular infection.

Aged↗

PubMed1990

Can the retroperitoneal approach be used for ruptured abdominal aortic aneurysms?

The retroperitoneal approach for elective treatment of abdominal aortic aneurysms is an accepted alternative to midline transperitoneal approaches and may provide less physiologic insult and a smoother postoperative course. In recent years we have preferentially used the extended retroperitoneal approach for ruptured abdominal aortic aneurysms to derive similar physiologic benefits for these patients. Over a 6-year period (1983 to 1989) 76 cases of ruptured abdominal aortic aneurysms were treated by emergency aortic replacement. After exclusion of 13 patients whose aneurysmal ruptures were unusual, such as aortoenteric fistula, aortocaval fistula, chronic contained rupture, or visceral involvement, 63 patients were retrospectively studied. Thirty-eight patients were treated via a standard transperitoneal celiotomy and 25 via a left retroperitoneal incision. No significant differences were found between the two groups in regard to cardiac or pulmonary function or duration of preoperative hypotension. Operative mortality was lower in the retroperitoneal group (three of 25, 12%) as compared to the transperitoneal group (13 of 38, 34.2%). Furthermore, the retroperitoneal group required less ventilatory support and tolerated enteral feedings quickly. Length of stay in the hospital was also significantly reduced in the retroperitoneal group. These data indicate that many ruptured abdominal aortic aneurysms can be successfully treated through the left retroperitoneal approach. In this nonrandomized clinical series increased survival rates and shorter periods of postoperative recovery were noted in the patients operated with the retroperitoneal approach.

Aorta, Abdominal↗

PubMed1990

Isolation and Characterization of the Genes Encoding Basic and Acidic Chitinase in Arabidopsis thaliana.

Plants synthesize a number of antimicrobial proteins in response to pathogen invasion and environmental stresses. These proteins include two classes of chitinases that have either basic or acidic isoelectric points and that are capable of degrading fungal cell wall chitin. We have cloned and determined the nucleotide sequence of the genes encoding the acidic and basic chitinases from Arabidopsis thaliana (L.) Heynh. Columbia wild type. Both chitinases are encoded by single copy genes that contain introns, a novel feature in chitinase genes. The basic chitinase has 73% amino acid sequence similarity to the basic chitinase from tobacco, and the acidic chitinase has 60% amino acid sequence similarity to the acidic chitinase from cucumber. Expression of the basic chitinase is organ-specific and age-dependent in Arabidopsis. A high constitutive level of expression was observed in roots with lower levels in leaves and flowering shoots. Exposure of plants to ethylene induced high levels of systemic expression of basic chitinase with expression increasing with plant age. Constitutive expression of basic chitinase was observed in roots of the ethylene insensitive mutant (etr) of Arabidopsis, demonstrating that root-specific expression is ethylene independent. Expression of the acidic chitinase gene was not observed in normal, untreated Arabidopsis plants or in plants treated with ethylene or salicylate. However, a transient expression assay indicated that the acidic chitinase promoter is active in Arabidopsis leaf tissue.

Journal Article↗

PubMed1990

Complications of pregnancy in infertile couples: routine treatment versus assisted reproduction.

Ninety pregnancies conceived by infertile couples using assisted reproductive technologies and 86 pregnancies conceived by infertile couples with routine infertility treatment were analyzed to determine the outcome of and the complications experienced during the pregnancies. Pregnancies ending after 24 weeks' gestation were evaluated for the following complications: pregnancy-induced hypertension, diabetes mellitus, preterm labor, premature rupture of membranes, placenta previa, and fetal growth retardation. A matched control group of normal fertile patients admitted to the obstetric service at Vanderbilt University Medical Center was used to compare the incidence of pregnancy complications among the groups. In the group treated by assisted reproduction, 81 pregnancies were singleton and nine were multiple gestations, whereas in the routine group, 84 were singleton and two were multiple gestations. In the group treated by assisted reproduction, 29 of 90 gestations (32%) ended before 24 weeks, compared with 18 of 86 (21%) in the routine group, a nonsignificant difference. Mean birth weight and gestational age were similar among the three groups for singleton gestations. Among multiple gestations, the mean (+/- standard error of the mean [SEM]) birth weights were 2513 +/- 115, 724 +/- 57, and 2282 +/- 132 g in the group treated by assisted reproduction, the group receiving routine methods, and the control group, respectively (P less than .001 when those treated by routine methods were compared with the other two groups). The mean (+/- SEM) gestational ages were 36 +/- 1.2, 26.5 +/- 2.0, and 35.5 +/- 1.2 weeks, respectively (P less than .01 comparing those treated by routine methods and the other two groups).(ABSTRACT TRUNCATED AT 250 WORDS)

Abortion, Spontaneous↗

PubMed1990

Immediate preoperative phlebotomy with autologous blood donation for aortic replacement.

The preferential use of autologous blood provided by phlebotomy can reduce the need for homologous blood transfusion in patients undergoing extensive elective operations. This blood is usually provided either by intraoperative isovolemic hemodilution or phlebotomy one to two weeks preoperatively. To minimize the intraoperative time delay or preoperative period between phlebotomy and operation required in these patients, we performed preoperative isovolemic hemodilution in 69 patients one to two days prior to elective aortic replacement for infrarenal aneurysmal disease. Patients underwent phlebotomy a mean of 0.57 +/- 0.01 liter of whole blood; volume was replaced with lactated Ringer's solution. Hematocrit levels decreased from a mean value of 42.9 +/- 0.4 per cent to 33.7 +/- 0.3 per cent. Mean intraoperative blood loss was 1.2 +/- 0.05 liters. Hemodynamic parameters (blood pressure, cardiac output, pulmonary capillary wedge pressure, central venous pressure, oxygen delivery and systemic vascular resistance) remained stable throughout the perioperative and intraoperative time periods. In addition, we evaluated the technical modification of exclusion aneurysmorrhaphy (n = 50) versus open aneurysmorraphy (n = 19) on reduction of intraoperative homologous blood transfusion in these patients. Seventy-two per cent (36 of 50) of patients whose aneurysms were excluded received no homologous blood intraoperatively. Blood loss was decreased in the excluded versus open aneurysmorraphy group, 920 +/- 90 milliliters versus 2,030 +/- 250 milliliters, as were homologous blood transfusion requirements, 175 +/- 35 milliliters versus 570 +/- 119 milliliters. Two patients died (2.9 per cent mortality rate), and there was no increase in morbidity. Surgical treatment of large aortic aneurysms is frequently performed on an urgent basis; thus, provision of autologous blood for this operation in a short period of time may be beneficial. Isovolemic hemodilution performed during the immediate preoperative period can reduce homologous blood requirements and be safely performed without adverse effects on mortality, morbidity and myocardial performance. Exclusion aneurysmorrhaphy may further reduce dependence on homologous blood.

Aorta, Abdominal↗

PubMed1990

Results of infrainguinal bypass for limb salvage in patients with end-stage renal disease.

Limb salvage in patients with end-stage renal disease (ESRD) is complicated by the diffuse, obstructive, calcific arteriopathy that makes anastomotic technique especially critical. Furthermore, decreased resistance to infection and impaired wound healing produced by host-factor deficiencies such as diabetes mellitus, hypoalbuminemia, uremia, and immunosuppression produce additional obstacles to successful limb salvage. This report summarizes our experience with distal arterial bypass procedures in these patients. A total of 32 bypass procedures were performed for limb salvage in 24 patients (17 diabetic) during a period of 5 years. The operative mortality rate was 6%. During the same period, 635 infrainguinal bypass procedures were performed by the in situ technique in patients without ESRD. Primary bypass patency was comparable in both groups at 24 months (92% vs 90%). In the group with ESRD, overall limb salvage was 83% at 2 years. Life-table analysis of bypass patency and limb salvage was thought not to be appropriate in the population with ESRD beyond 2 years because of the increased mortality rate (38%; 9/24) during this interval. It is important that limb salvage was achieved in diabetic patients with ESRD in the presence of extensive foot gangrene or ischemic ulceration. Revascularization should be considered strongly for limb salvage in all patients in this difficult population.

Adult↗

PubMed1990

An animal model for instructing and the study of in situ arterial bypass.

A canine model that used the cephalic vein to bypass from the brachial to the ulnar artery was designed for use in instructing and evaluating surgical technique needed for constructing an in situ arterial bypass. This model was used for instructing vascular residents in the in situ vein bypass technique. The use of this model enabled the resident to become more adept with the instruments for valve incision and construction of small vessel anastomosis. The improvement in the resident's operative technique was reflected by a decrease in the number of technical complications (missed valves, missed arteriovenous fistulas, poorly constructed anastomoses) and improved patency rate.

Animals↗

PubMed1990

Hemodynamic characteristics of failing infrainguinal in situ vein bypass.

The successful follow-up of distal arterial reconstructions for the identification of the failing bypass in the postoperative period hinges on a knowledge of the natural history of flow characteristics in these reconstructions. Over a 4-year period resting and hyperemic bypass flow, fistula flow, conduit diameter, and distal peak systolic velocity of 350 in situ bypasses were measured serially. B-mode ultrasound imaging of the entire bypass was performed to identify specific stenoses. Measurements were performed 5 to 9 days after operation, every 2 months for the first year, and every 6 months thereafter. Distal bypass flow less than 25 ml/min, a ratio of hyperemic/resting distal bypass flow less than 2.5, and vein size less than or equal to 3.0 mm inner diameter all correlated with bypass stenosis (greater than 50%) or occlusion (p less than 0.01). Contrary to previous studies, a distal peak systolic velocity of less than 45 cm/sec did not correlate with bypass stenosis or occlusion. A low distal peak systolic velocity did correlate with bypass stenosis or occlusion in bypasses larger than or equal to 3.5 mm inner diameter (p less than 0.03). However, no combination of these factors was able to accurately predict preocclusive stenosis or occlusion. Distal bypass flow was highest initially but reached a plateau 6 to 12 months after operation. Fistula flow, although very high initially, showed marked decrement with time.

Aged↗

PubMed1990

Remote distal arteriovenous fistula to improve infrapopliteal bypass patency.

The results of the use of prosthetic materials for femorocrural bypass surgery have been less than optimal. The creation of a distal anastomotic arteriovenous fistula to augment blood flow and velocity through the graft is well known. However, it may create turbulence at the anastomosis and steal blood flow away from the distal artery. A canine model was developed to evaluate the effect of fistula size on graft/arterial hemodynamics. In 16 patients we have constructed a distal arteriovenous fistula, which is remote from the distal anastomosis, and we studied the effect of such fistulas on bypass patency and distal arterial hemodynamics. Patients selected for this procedure had multiple previously failed reconstructions and limb-threatening ischemia and did not have usable autogenous vein. Femorotibial bypass graft reconstructions were performed with polytetrafluoroethylene followed by the creation of a side-to-side arteriovenous fistula 5 to 15 cm below the distal anastomosis in the same artery and accompanying veins. We have achieved a 1-year patency of 67% with a 75% limb salvage rate. We also serially measured blood flow and velocity within the bypass, the arteriovenous fistula, and the distal outflow vessel using duplex scanning after surgery. Mean estimated blood flow through the bypass during the immediate postoperative period was 264 ml/min, the arteriovenous fistula was 157 ml/min, and the distal artery was 19 ml/min. Unlike an arteriovenous fistula created at the distal anastomosis, a remote distal arteriovenous fistula not only increases graft blood flow but also augments native arterial blood flow between the distal anastomosis and fistula and thus may improve distal limb perfusion.

Animals↗

PubMed1990

Sonographic evaluation of maternal disorders during pregnancy.

This article has reviewed and illustrated the sonographic features of the most common pelvic masses that can be encountered in pregnant patients. Sonographic evaluation allows delineation of the size, consistency, and location of pelvic masses occurring during pregnancy. It has an important role in establishing the enlargement or regression of pelvic masses that occur during pregnancy. Sonography also has an important role in the diagnosis of cholecystitis and upper urinary tract obstruction and/or infections in the pregnant patient.

Cholelithiasis↗

PubMed1989

Role of B-mode venous mapping in infrainguinal in situ vein-arterial bypasses.

Two hundred and eighty patients underwent B-mode mapping (B-map) of their saphenous vein over a period of 3 years (1984-1987) before lower limb revascularization. B-map deemed that 229 veins were suitable for bypass, 26 were questionable and 25 were unsuitable. A successful bypass was achieved in 97.8 per cent of the suitable group (all in situ), 85 per cent of the questionable group (in situ and composite vein), and 80 per cent of the unsuitable group (composite vein). At a minimum follow-up period of 1 year the overall patency rate was 95.0 per cent with a revision rate of 15.8 per cent. There was no correlation between revision rate and vein complexity or calf vein diameter. Calf vein diameter greater than 2.5 mm was correlated with a successful bypass (P less than 0.001). It is concluded that B-map is the investigation of choice for saphenous vein assessment before infrainguinal bypass surgery.

Aged↗

PubMed1989

Fish-oil dietary supplementation in patients with Raynaud's phenomenon: a double-blind, controlled, prospective study.

PURPOSE: The ingestion of omega-3 fatty acids could benefit patients with Raynaud's phenomenon because, among other effects, these fatty acids induce a favorable vascular response to ischemia. The aim of our study was to investigate, in a double-blind, placebo-controlled manner, the effects of fish-oil fatty-acid dietary therapy in patients with rheumatic disease. PATIENTS AND METHODS: Thirty-two patients with primary or secondary Raynaud's phenomenon were randomly assigned to olive-oil placebo or fish-oil groups. Patients ingested 12 fish-oil capsules daily containing a total of 3.96 g eicosapentaenoic acid and 2.64 g docosahexaenoic acid or 12 olive-oil capsules and were evaluated at baseline and after six, 12, and 17 weeks. All patients ingested olive oil between Weeks 12 to 17. Digital systolic blood pressures and blood flow were measured at room air and water baths of 40 degrees C, 25 degrees C, 15 degrees C, and 10 degrees C using strain gauge plethysmography. Onset of Raynaud's phenomenon was timed with a stop watch and defined as plethysmographic evidence of cessation of blood flow and blood pressure in the study finger. RESULTS: In the fish-oil group, the median time interval before the onset of Raynaud's phenomenon increased from 31.3 +/- 1.3 minutes baseline to 46.5 +/- 2.1 minutes at six weeks (p = 0.04). Patients with primary Raynaud's phenomenon ingesting fish oil had the greatest increase in the time interval before the onset of the condition. Five of 11 patients (45.5 percent) with primary Raynaud's phenomenon ingesting fish oil in whom the phenomenon was induced at baseline could not be induced to develop Raynaud's at the six- or 12-week visit compared with one of nine patients (11 percent) with primary Raynaud's ingesting olive oil (p = 0.05). The mean digital systolic pressures were higher in the patients with primary Raynaud's phenomenon ingesting fish oil than in patients with primary Raynaud's ingesting olive oil in the 10 degrees C water bath (+32 mm Hg, p = 0.02). CONCLUSION: We conclude that the ingestion of fish oil improves tolerance to cold exposure and delays the onset of vasospasm in patients with primary, but not secondary, Raynaud's phenomenon. These improvements are associated with significantly increased digital systolic blood pressures in cold temperatures.

Adult↗