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Biomedical subjects

D M Shah

Publications and source records attributed to D M Shah.

At least 163 records · Page 9Linked to original sources
PubMed1988

Thromboxane release after reperfusion of chronically ischemic limbs in patients.

We hypothesized that chronic ischemia of peripheral vascular disease would lead to increased thromboxane A2 (TxA2) and decreased prostacyclin (PGI2) production and surgical correction of the ischemia would stabilize TxA2 and PGI2 at normal levels. TxA2 and PGI2 concentrations were determined in 22 patients before, during, and after arterial reconstruction for limb salvage and in 10 control subjects. Control samples and preoperative patient samples had no detectable TxA2 or PGI2 (less than 26 pg/ml). Five minutes after reperfusion TxA2 increased (TxA2 = 76.27 +/- 48.9 pg/ml, mean +/- SEM) and persisted at 1 day (TxA2 = 190.1 +/- 80.1 pg/ml), 2 days (TxA2 = 224.7 +/- 131.7 pg/ml), 5 days (TxA2 = 334.8 +/- 272.8 pg/ml), and 7 days postoperatively (TxA2 = 256.6 +/- 149.0 pg/ml). Elevated TxA2 production was not associated with chronic ischemia of peripheral vascular disease. Reperfusion of the severely ischemic limb caused significant TxA2 release.

Adult↗
PubMed1987

Bacterial expression and isolation of Petunia hybrida 5-enol-pyruvylshikimate-3-phosphate synthase.

5-enol-Pyruvylshikimate-3-phosphate synthase (EPSP synthase, EPSPS), an in vivo enzyme target of the herbicide glyphosate (N-phosphonomethyl glycine), was purified from a Petunia hybrida suspension culture line, MP4-G, by a small-scale high-performance chromatographic purification procedure. The cDNA encoding the mature petunia EPSPS (lacking the chloroplast transit sequence) was cloned into a plasmid, pMON342, for expression in Escherichia coli. This clone complemented the EPSPS deficiency of an E. coli aroA- mutant, and the plant enzyme constituted approximately 1% of the total extractable protein. Large-scale purification of the enzyme from E. coli cells resulted in a highly active protein which was homogeneous as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and amino terminal sequencing. Antibodies raised against the purified enzyme also reacted with the E. coli EPSPS in Western analyses. The availability of large quantities of the plant enzyme will significantly facilitate mechanistic investigations as well as a comparative study with EPSPS from bacteria and fungi.

3-Phosphoshikimate 1-Carboxyvinyltransferase↗
PubMed1987

The influence of anesthetic choice on carotid endarterectomy outcome.

This study compared the technique of general and regional cervical block anesthesia for carotid endarterectomy. Three hundred sixty-eight patients undergoing 399 carotid endarterectomies were administered one of these alternative anesthetics as selected preoperatively by each patient and his or her physician. In 242 cases general anesthesia was used. The other 157 cases were done under regional cervical block anesthesia. Perioperative mortality was 1.0%. Nonfatal strokes occurred in 1.25%. There were significantly more strokes in the general anesthesia group. Perioperative blood pressure was unstable for a significantly longer period of time after general anesthesia (mean, 24.6 hours) as compared with regional cervical block anesthesia (mean, 2.1 hours). Furthermore, vasoactive drugs were required for significantly longer periods of time in the general anesthesia group.

Adult↗
PubMed1987

Duplex scanning of the internal carotid artery: an assessment of cerebral blood flow.

Duplex ultrasound scanning (B-mode imaging and pulsed Doppler shift analysis) was used to measure internal carotid artery blood flow (ICBF) in 20 volunteers. The effect of changes in end tidal CO2 on cerebral blood flow was measured. When corrected to a PCO2, of 40 torr (5.32 kPa) internal carotid artery blood flow was 286 +/- 16 ml min-1 (mean +/- s.e.m.). Specific CO2 reactivity (the change in flow per torr change in CO2) was 8.16 +/- 0.69 ml min-1 torr-1 which was equivalent to 2.0 +/- 0.1 per cent of the flow at 40 torr per torr change in CO2 (percentage CO2 reactivity). The mean value and the CO2 reactivity compare favourably with previously reported measurements by other techniques. These data suggest that the non-invasive measurement of internal carotid artery blood flow by Doppler ultrasound scanning is an assessment of cerebral blood flow that can be used to study both normal and pathological changes within the cerebral circulation.

Blood Flow Velocity↗
PubMed1987

Expression of alfalfa mosaic virus coat protein gene confers cross-protection in transgenic tobacco and tomato plants.

A chimeric gene encoding the alfalfa mosaic virus (AlMV) coat protein was constructed and introduced into tobacco and tomato plants using Ti plasmid-derived plant transformation vectors. The progeny of the self-fertilized transgenic plants were significantly delayed in symptom development and in some cases completely escaped infection after inoculated with AlMV. The inoculated leaves of the transgenic plants had significantly reduced numbers of lesions and accumulated substantially lower amounts of coat protein due to virus replication than the control plants. These results show that high level expression of the chimeric viral coat protein gene confers protection against AlMV, which differs from other plant viruses in morphology, genome structure, gene expression strategy and early steps in viral replication. Based on our results with AlMV and those reported earlier for tobacco mosaic virus, it appears that genetically engineered cross-protection may be a general method for preventing viral disease in plants.

Journal Article↗
PubMed1987

Use of the short saphenous vein in situ for popliteal-to-distal artery bypass.

In the absence of a usable greater saphenous vein, the short saphenous vein has been relatively ignored for use as an arterial bypass conduit. In 36 patients, duplex ultrasound scanning was used for preoperative assessment of the short saphenous vein. The internal diameter of the vein ranged from 2.8 to 4.2 mm. The short saphenous vein was harvested for a free vein graft in 31 patients. In the remaining five patients, the short saphenous vein was used in situ for popliteal-to-distal artery bypass. In four patients, the distal anastomosis was performed to the distal anterior tibial artery and in one patient, to the distal posterior tibial artery. Valves were excised with valvulotomes and deep fistulas were easily ligated. A medial incision for vein exposure was the preferred approach. We suggest that the short saphenous vein be considered more often for use as an arterial bypass conduit when the greater saphenous vein is not available, before submitting to nonautogenous bypass or primary amputation.

Arteriovenous Shunt, Surgical↗
PubMed1987

Management of pediatric visceral arterial and aortic coarctation.

Two unusual pediatric vascular problems have been managed surgically. The first patient is a five-and-a half-year old girl who presented with renal artery stenosis and aneurysm and renovascular hypertension. This was treated by excision of the aneurysm and reimplantation of the right renal artery. The second patient is a two-year old girl with atresia of the abdominal aorta, superior mesenteric artery (SMA) and both renal arteries. She was treated by PTFE patch graft angioplasty of the aorta, SMA reimplantation and bilateral aorto-renal autogenous saphenous vein bypass.

Aneurysm↗
PubMed1987

Urinary 19-nor-deoxycorticosterone and deoxycorticosterone in hypertensive disease of pregnancy.

Normal pregnancy and pre-eclampsia are associated with water and sodium retention. Therefore various mineralocorticoids have been evaluated in normal and abnormal pregnancies. This study reports the urinary free 19-nor-deoxycorticosterone (19-nor-DOC) and deoxycorticosterone (DOC) levels in normal pregnancy and in patients with pregnancy-induced hypertension. Levels of 19-nor-DOC and DOC were not significantly different between normal patients in the third trimester and women with pregnancy-induced hypertension at a comparable gestational age. The urinary excretion of 19-nor-DOC in pregnancy was noted to be significantly lower than that previously reported in normal male volunteers. There was a positive correlation between 19-nor-DOC excretion and increasing gestational age. These data are compatible with the view that 19-nor-DOC may not play a role in pregnancy-induced hypertension. However, a larger study of primigravid women, with and without, pre-eclampsia is needed to confirm this finding.

Adult↗
PubMed1987

Influence of hematocrit on cardiopulmonary function after acute hemorrhage.

The 'optimal' hematocrit to which patients should be resuscitated after shock and trauma is controversial. To test the hypothesis that sufficient oxygen delivery can be provided at a lower hematocrit without impairing oxygen consumption or hemodynamic function, 25 patients were prospectively studied immediately following injury and/or acute hemorrhage. Patients were randomized to have their hematocrits (HCT) maintained near 30% (29.7 +/- 0.4% (M +/- SEM); n = 12) or 40% (38.4 +/- 0.6%, n = 13). Cardiopulmonary parameters were measured twice a day for 3 days. Statistical analysis used a repeated measures analysis of variance with patient age, and ventilator parameters (FIO2, PEEP, and ventilator mode) as covariates. Arterial and venous O2 saturations were not significantly different at different hematocrits, although arterial and venous O2 contents were lower at 30% HCT (a = 14.1 +/- 0.2 m10(2)/dl, v = 10.1 +/- 0.3 m10(2)/dl; vs. a = 17.4 +/- 0.4 m10(2)/dl, v = 13.6 +/- 0.6 m10(2)/dl; p less than 0.05). This resulted in a lower oxygen delivery at the lower HCT. Between the two groups, there also was no significant difference in cardiac index (overall mean, 3.64 +/- 0.16 ml/min/m2), heart rate (99 +/- 4 bpm), systemic vascular resistance (1,058 +/- 55 dyne-sec/cm5), or left ventricular stroke work index (4.3 +/- 0.3 X 10(6) dyne-cm/m2). Intrapulmonary shunt was higher with higher hematocrit (22.6 +/- 2.4% at 40% HCT vs. 14.6 +/- 1.6% at 30% HCT; p less than 0.05) with no difference in end-expiratory pressure.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗
PubMed1987

Acute fatty liver of pregnancy: etiology of fetal distress and fetal wastage.

Acute fatty liver is a rare complication of pregnancy occurring in approximately one in 13,000 deliveries. This disease has been associated with high maternal and fetal mortality rates in the past. Advances in medical care and early recognition and delivery are credited with recent reductions in the maternal and fetal loss seen with this disease. Maternal death is associated with hypoglycemia, hepatic failure, or coagulopathy. The etiology of fetal mortality is not well delineated. Reported is a patient with histologically proved acute fatty liver who developed fetal distress during therapy for coagulopathy. Review of the fetal monitor tracing in conjunction with examination of the placenta have led us to propose that uteroplacental insufficiency may be the cause for fetal distress and fetal wastage in fatty liver of pregnancy.

Acute Disease↗
PubMed1986

The genes encoding the small subunit of ribulose-1,5-bisphosphate carboxylase are expressed differentially in petunia leaves.

We have isolated five members of the multigene family encoding the small subunit (rbcS) of ribulose-1,5-bisphosphate carboxylase in petunia and examined their expression in petunia leaves. Of the five rbcS genes, two (ssu11A and ssu8) are expressed at high levels in petunia leaves. Northern analysis using gene specific oligonucleotide probes revealed that ssu11A accounts for 40% of the total rbcS transcripts in petunia leaves while ssu8 accounts for 4 to 5% of the total rbcS transcripts. Structural comparisons of ssu8 and ssu11A revealed that the coding sequence of ssu8 is interrupted by three introns, while the coding sequence of ssu11A is interrupted by two introns. The positions of the first two introns are identical, the third intron in ssu8 is located in a highly conserved region of the protein. The 5' and 3' flanking sequences of ssu11A are highly homologous to the 5' and 3' flanking sequences of ssu8. S1 nuclease mapping was used to locate the start of transcription of ssu8 and ssu11A and showed that ssu8 mRNA leader differs in sequence from the ssu11A mRNA leader.

Amino Acid Sequence↗
PubMed1986

Pulmonary and cardiovascular consequences of immediate fixation or conservative management of long-bone fractures.

We randomly assigned patients with multiple trauma who had tibial or femoral fractures to one of two groups--one group received immediate fixation of all fractures, and the second group received conservative orthopedic management, consisting of traction or plaster casts. Studies were conducted twice each day for four days following injury. Mean cardiac index was 1.3 L/min/m2 higher and mean shunt was 5.2% lower in the immediate fixation group compared with the group receiving conservative treatment. Other pulmonary and systemic hemodynamic variables did not differ between the groups. The incidence of fat macroglobules in blood aspirated from the pulmonary capillaries was higher when compared with that in pulmonary arterial blood but was not significantly different between the two treatment groups. Platelet count was significantly lower and fibrinogen concentration was significantly higher in the group receiving immediate fixation. We found no diagnostic significance of the incidence of fat macroglobules in samples of blood aspirated from the pulmonary circulation. We conclude that patients receiving immediate fixation had less pulmonary dysfunction following multiple trauma and long-bone fractures.

Adolescent↗
PubMed1986

The structure and expression of maize genes encoding the major heat shock protein, hsp70.

We have isolated and sequenced two maize genomic clones that are homologous to the Drosophila hsp70 gene. One of the maize hsp70 clones contains the entire hsp70 coding region and 81 nucleotides of the 5' nontranslated sequence. The predicted amino acid sequence for this maize protein is 68% homologous to the hsp70 of Drosophila. The second maize hsp70 clone contains only part of the coding sequence and 1.1 kb of the 5' flanking sequence. This 5' flanking sequence contains two sequences homologous to the consensus heat-shock-element sequence. Both maize genes are thermally inducible and each contains an intron in the same position as that of the heat-shock-cognate gene, hsc1, of Drosophila. The presence of an intron in the maize genes is a distinguishing feature in that no other thermally inducible hsp70 genes described to date contain an intron. We have constructed a hybrid hsp70 gene containing the entire hsp70 coding sequence with an intron, and 1.1 kb of the 5' flanking sequence. We demonstrate that this hybrid gene is thermally inducible in a transgenic petunia plant and that the gene is expressed from its own promoter.

Journal Article↗