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Biomedical subjects

M K Ali

Publications and source records attributed to M K Ali.

At least 37 records · Page 2Linked to original sources
PubMed1999

Cloning, sequencing, and expression of the gene encoding the Clostridium stercorarium xylanase C in Escherichia coli.

The nucleotide sequence of the Clostridium stercorarium F-9 xynC gene, encoding a xylanase XynC, consists of 3,093 bp and encodes a 1,031-amino acids with a molecular weight of 115,322. XynC is a multidomain enzyme composed of an N-terminal signal peptide and six domains in the following order: two thermostabilizing domains, a family 10 xylanase domain, a family IX cellulose-binding domain, and two S-layer homologous domains. Immunological analysis indicated the presence of XynC in the culture supernatant of C. stercorarium F-9 and in the cells, most likely on the cell surface. XynC purified from a recombinant E. coli was highly active toward xylan and slightly active toward p-nitrophenyl-beta-D-xylopyranoside, p-nitrophenyl-beta-D-cellobioside, p-nitrophenyl-beta-D-glucopyranoside, and carboxymethylcellulose. XynC hydrolyzed xylan and xylooligosaccharides larger than xylotriose to produce xylose and xylobiose. This enzyme was optimally active at 85 degrees C and was stable up to 75 degrees C at pH 5.0 and over the pH range of 4 to 7 at 25 degrees C.

Amino Acid Sequence↗
PubMed1998

Donor hepatitis C virus status does not adversely affect short-term outcomes in HCV+ recipients in renal transplantation.

BACKGROUND: Recipient hepatitis C virus (HCV) seropositivity has been associated with inferior outcomes in renal transplantation (RTx). We sought to determine whether donor HCV+ status influenced the incidence of rejection, liver dysfunction, and graft survival in HCV+ recipients. METHODS: We reviewed 44 HCV+ recipients (R+) receiving RTx from HCV+ (D+) and HCV- (D-) donors between February 1991 and September 1996. All patients were followed to the end of the study period (mean=36 months, range=12-60 months). We compared the R+ group with a demographically matched cohort of 44 HCV- recipients (R-). RESULTS: Of the 44 R+, 25 (57%) had a total of 48 rejection episodes. Among the 44 R-, 32 (73%) had 58 rejection episodes (P>0.1). Within the R+ group, 28 were D+/R+; of these 14 (50%) had 27 rejection episodes, whereas among the 16 D-/R+, 11 (68%) had 21 rejection episodes (P>0.3). Graft and patient survival was similar in both the groups (86.4% and 91%, respectively). Liver dysfunction was slightly increased in the R+ group (4/44 vs. 0/44, P>0.1), with one death due to liver failure in this group. CONCLUSION: Donor HCV+ status had no influence on outcomes in HCV+ recipients after kidney transplantation in the short term. The incidence of rejection, graft loss, and mortality was comparable between the D+/R+ and D-/R+ groups. Furthermore, rejection, graft loss, and death were identical in R+ and R-groups throughout the 5-year study period. We therefore conclude that HCV+ recipients can safely receive kidney transplants without concern about donor HCV status or fear of adverse events from their own HCV+ status.

Adult↗
PubMed1998

Erythrocytes from healthy smokers bind more bilirubin than the erythrocytes from healthy non-smokers.

Cigarette smoking is an adverse prognostic factor for health. Its damaging effects on many enzymatic and cellular activities are well known. The present study was carried out to evaluate whether there is a difference in the binding of bilirubin to the erythrocytes from healthy smokers and non-smokers. The results suggest that the binding of bilirubin to the erythrocytes from healthy smokers as well as in vitro smoked erythrocytes is significantly higher than that of healthy non-smokers.

Adult↗
PubMed1998

Treatment of sigmoid volvulus: experience in Gondar, north-west Ethiopia.

A retrospective study of 145 patients with sigmoid volvulus (SV) seen over a three year period is presented. Sigmoid volvulus (SV) was the commonest cause of emergency admissions with intestinal obstruction (56%). The mean age was 55 +/- 13 years, (range 10-80), and the male to female ratio was 13.5:1. The presence or absence of a previous attack makes a significant difference in the occurrence of gangrenous bowel. Eighteen out of 75 patients (24%) with no previous attack had gangrenous bowel compared with 2 out of 57 (4%) after recurrence. A conservative sigmoidoscopic detorsion was successful in the majority of the cases (63%). Elective surgery after bowel preparation was associated with a mortality rate of 3% in comparison to 12.5 mortality rate in patients with viable bowel operated on an emergency basis (p < 0.05). Sigmoidoscopic detorsion should be the first measure in patients with viable bowel.

Adult↗
PubMed1997

Calcium-induced bilirubin-dependent hemolysis of human erythrocytes.

Human erythrocytes, preincubated with different concentrations of calcium chloride (0.17-1.67 mM) showed hemolysis after addition of bilirubin (72 microM). Hemolysis was observed only when cells were incubated first with calcium followed by bilirubin and not vice versa. This hemolysis was found to be dependent upon several factors such as concentration of bilirubin, time of incubation of erythrocytes with calcium and time of incubation of bilirubin with the calcium-loaded erythrocytes. Inclusion of EDTA in the incubation medium reduced the percentage hemolysis to a significant extent. Involvement of activated oxygen species in hemolytic process seems to be unlikely as inclusion of sodium azide and catalase did not prevent hemolysis. A comparison of other bivalent cations such as Ba2+, Mg2+, Mn2+ and Cu2+ with Ca2+ for their ability to hemolyse cells in presence of bilirubin shows that Ba2+ and Mg2+ are ineffective, whereas both Mn2+ and Cu2+ induce hemolysis both in the absence as well as in the presence of bilirubin. However, their mechanism of hemolysis is different from that of calcium-induced hemolysis. Formation of calcium-induced hydrophobic aggregates of phospholipid molecules in erythrocyte membrane may open the new binding sites for bilirubin on these membranes which may perturb the membrane conformation.

Azides↗
PubMed1997

Automatic postoperative monitoring of infrainguinal bypass procedures.

OBJECTIVE: To evaluate the usefulness of a portable, computer-based, oscillometric, noninvasive blood pressure monitor for the automatic surveillance of postoperative infrainguinal bypasses. DESIGN: Prospective unblinded study. SETTING: Regional tertiary care Veterans Affairs medical center. PATIENTS: A total of 60 limbs were examined in 3 groups (n = 20 in each group): normal, asymptomatic volunteers; older patients with symptomatic peripheral vascular disease; and patients who had undergone infrainguinal bypass procedures. INTERVENTIONS: Noninvasive blood pressure monitor pressures, complete lower extremity arterial studies with Doppler ankle-brachial index (ABI), segmental pressures, and pulse volume recordings were performed in all groups. The patients who had undergone surgery also had hourly noninvasive blood pressure measurements taken. MAIN OUTCOME MEASURES: Ankle-brachial indices obtained with the noninvasive blood pressure monitor were compared with simultaneous manual Doppler ABIs and pulse volume recordings. RESULTS: There was a significant overall correlation between the Doppler-derived ABIs and automatic oscillometric values (r = 0.89, P < .001). Although there was a slight difference in absolute values (+/-SEM) (0.90 +/- 0.03 vs 0.84 +/- 0.03, respectively), an excellent correlation was found between the 2 methods in the clinically relevant range of ABI values between 0.60 and 1.10. The oscillometric method, however, overestimated the ABI when it was less than 0.60 by the Doppler method (0.61 +/- 0.02 vs 0.44 +/- 0.03, P < .001) and underestimated it when it was more than 1.10 (1.05 +/- 0.02 vs 1.16 +/- 0.01, P < .001). (All values given as +/-SEM.) Oscillometric overestimation correlated with depressed pulse volume recording waveforms (P < .001) or diminished pulse volume recording amplitudes of less than 10 mm (P < .001). CONCLUSION: The automatic oscillometric monitor provides a useful, accurate, objective, and quantitative method for postoperative bypass graft surveillance.

Adult↗
PubMed1997

Binding of bilirubin to mammalian erythrocytes.

Binding of bilirubin to erythrocytes of various mammalian species in the presence of their respective plasma albumins was studied at pH 8.0, ionic strength 0.41 and at 37 degrees C. In human, buffalo, goat, and sheep, the amount of erythrocyte-bound bilirubin increased with the increase in both the bilirubin/albumin molar ratio (B/A) and the total bilirubin concentration. In all species, the binding patterns were qualitatively similar. However, at any given B/A, goat erythrocytes bound the highest amount of bilirubin, followed by buffalo and human erythrocytes; sheep erythrocytes bound the lowest amount of bilirubin. Increase in erythrocyte-bound bilirubin per unit increase in bilirubin concentration at a constant B/A as obtained from the values of the slope of the plot between erythrocyte-bound bilirubin and total bilirubin in the incubate, was found to be highest for goat erythrocytes, followed by buffalo, human, and sheep erythrocytes. At given bilirubin concentration, percentage fractional binding of bilirubin between any two B/As was found to be highest between 1.5 and 2.0, suggesting that a greater amount of bilirubin was transferred from plasma to cells between B/As 1.5 and 2.0. Percentage fractional binding of bilirubin was highest in goat erythrocytes, followed by buffalo, human, and sheep erythrocytes. These differences in the amount of erythrocyte-bound bilirubin were not due to the effect of various plasma albumins. These results suggest that the difference in bilirubin binding by different mammalian erythrocytes can be attributed to the difference in either the affinity of the erythrocyte receptors or their number or both.

Animals↗
PubMed1996

Vocal cord medialization for unilateral paralysis associated with intrathoracic malignancies.

Patients with unilateral vocal cord paralysis from intrathoracic malignancies may have significant dysfunctions of speech, swallowing, ventilation, and effective coughing as a result of inadequate compensation of the nonparalyzed cord. In patients with already compromised pulmonary function, aspiration can be a life-threatening event. Sixty-three patients with intrathoracic malignancies required surgical correction of vocal cord paralysis. Primary pathology included lung cancer (49), esophageal cancer (nine), and miscellaneous tumors (five). Symptoms included hoarseness (62), dyspnea (21), aspiration (26), weight loss (19), dysphagia (14), and pneumonia (14). The surgical procedures included medial displacement of the vocal cord with silicone elastomer (48), temporary Gelfoam injection (seven), and Teflon (polytetrafluoroethylene) injection (eight) to move the affected cord to a medial position. In 11 patients, the operation was performed in the acute postoperative setting to improve pulmonary toilet. Symptomatic improvement was noted in the following proportions of affected patients: hoarseness, 92%; dyspnea, 90%; dysphagia, 93%; aspiration, 92%; pneumonia, 93%; and weight loss, 47%. Overall success rate of the intervention was 57 of 63 patients (90%). All 11 patients treated in the acute setting had immediate improvement. A variety of complications occurred in 17% of patients. Surgical management of vocal cord paralysis in patients with intrathoracic malignancies prevents life-threatening pulmonary complications in the acute postoperative setting. In chronic situations, it provides patients with improved speech, swallowing, and pulmonary function, resulting in improved quality of life, even for patients not cured of their disease.

Adult↗
PubMed1995

Interference of sodium azide with the quantitation of bilirubin: modification of Fog's method to eliminate azide interference.

Interference of sodium azide with bilirubin estimation was studied at different concentrations of sodium azide. At an azide concentration (0.08% or 12.3 mM), 99% inhibition of the color reaction was observed. Similar results were obtained when the effect of sodium azide was studied by fixing bilirubin concentration and increasing the azide concentration. The decrease in color reaction can be explained on the basis of competition of the two compounds, i.e., bilirubin and sodium azide for diazosulfanilic acid. The method was modified to measure the concentration of bilirubin in various serum samples containing different amounts of sodium azide.

Azides↗
PubMed1995

Binding of bilirubin to erythrocytes from different mammalian species.

The binding of bilirubin to erythrocytes of several mammalian species, i.e. human, buffalo, goat and sheep was studied. In all cases, curves between bilirubin desorbed from erythrocytes and bilirubin in the incubate followed Michaelian saturation kinetics. The dissociation constants of the bilirubin-receptor complex and saturable binding sites were calculated using double reciprocal plots. Goat erythrocytes had the highest dissociation constant (265.7 mumol/l) and highest saturation (125.9 microM), whereas sheep erythrocytes had the lowest dissociation constant (115.6 mumol/l) and lowest saturation (62.5 microM). Buffalo and human erythrocytes bound bilirubin in a similar fashion, and the values of interaction parameters were midway between those obtained with goat and sheep erythrocytes. Differences in the affinity and number of saturable binding sites can be attributed to the different make-up of the erythrocyte membranes of these species.

Animals↗
PubMed1994

Late doxorubicin-associated cardiotoxicity in children. The possible role of intercurrent viral infection.

BACKGROUND: The most frequently encountered doxorubicin related cardiac toxicity is a dose-related myocardial dysfunction occurring 1-6 months after chemotherapy. Recently, late cardiotoxicity has been the focus of interest. This paper explores the possibility that acute intercurrent viral illness may trigger late cardiotoxicity. METHODS: Thirty selected pediatric patients were followed for changes in their echocardiographically measured fractional shortening (FS) for 2-10 years after completion of their doxorubicin chemotherapy. They were divided according to the dose of doxorubicin they received (< 300 mg/m2 or > or = 300 mg/m2) and to whether the manifestations of an acute intercurrent viral illness during the observation period were documented. Eleven patients experienced such infections. RESULTS: Changes in FS demonstrated two different responses. The usual response to doxorubicin was a gradual, dose-related fall in FS, followed by recovery; while the second response included an unexpected, late, sudden decrease in FS. Four patients in the low dose subgroup experienced an acute intercurrent viral illness, but none of these demonstrated the unexpected decrease. Of the seven patients who acquired such illness in the high dose subgroup, five demonstrated the sudden, late decrease in FS, with two of them developing severe, reversible congestive heart failure. CONCLUSIONS: The most likely explanation for the late, sudden decrease in FS is an additional stress in patients who already have sustained subclinical cardiac damage as a result of their doxorubicin chemotherapy. An acute intercurrent viral illness may have triggered late cardiac dysfunction in some of these patients.

Acute Disease↗
PubMed1994

Cardiac diastolic function in pediatric patients receiving doxorubicin.

The purpose of the study was to compare systolic and diastolic function in pediatric patients treated with doxorubicin. Left ventricular function was evaluated in 61 children prior to and following chemotherapy. None had clinical evidence of cardiac decompensation prior to treatment. All received relatively low cumulative doses of doxorubicin; the majority received the drug by continuous infusion. Systolic function was estimated using fractional shortening; diastolic function was estimated using A wave velocity, E wave velocity, E to A ratio, and deceleration time. There was a small but significant decline in systolic cardiac function as estimated from changes in fractional shortening that could not be appreciated in any of the measured parameters of diastolic function. A variety of reasons that could be responsible for the absence of significant changes in diastolic function are discussed. For the present, estimations of systolic function are preferred over the studied parameters of diastolic function in the evaluation of cardiac status in pediatric patients receiving doxorubicin containing regimens.

Adolescent↗
PubMed1992

Postoperative atrial fibrillation in cancer surgery: preoperative risks and clinical outcome.

Postoperative atrial fibrillation (AF) is a recognized complication of cancer surgery. The purpose of this study was to define preoperative risk factors for AF, and to evaluate the clinical significance of the arrhythmia. We reviewed the medical records of 43 patients with postoperative AF admitted to the surgical intensive care unit (SICU). All patients were older than 60 years, 79% had a history of cigarette smoking, and 44% had hypertension. AF occurred an average of 2.8 days following surgery, and lasted an average of 2.1 days. No significant complications developed, and there were no long-term sequelae. This study suggests that, in cancer patients, postoperative AF is a disease of elderly patients. In addition the arrhythmia appears to be a relatively transient and benign phenomenon. Prolonged monitoring in an intensive care setting may not be necessary for asymptomatic, hemodynamically stable patients.

Aged↗
PubMed1992

Exercise testing in the evaluation of patients at high risk for complications from lung resection.

Exercise testing was performed on 37 patients with resectable lung lesions who were deemed inoperable because of any of the following risk factors: (1) FEV1 less than or equal to 40 percent of predicted; (2) radionuclide calculated postlobectomy FEV1 less than or equal to 33 percent of predicted; or (3) arterial PCO2 greater than or equal to 45 mm Hg. The patients who reached a peak level of oxygen consumption during exercise (VO2Peak) of greater than or equal to 15 ml/kg/min were offered surgical treatment. Patients with a VO2Peak of less than 15 ml/kg/min were referred for nonsurgical management and excluded from the study. Eight patients underwent lung resection. Their pulmonary function revealed a severe obstructive lung defect with a group mean predicted FEV1 of 40 +/- 6 percent, an FEV1/FVC ratio of 47 +/- 10, a radionuclide calculated postlobectomy FEV1 of 31 +/- 4 percent, and a mean arterial PCO2 of 44 +/- 6 mm Hg. No relationship was found between each patient's exercise performance and spirometric function. Six of the patients had an uncomplicated postoperative course. Two patients had complications but no patient died as a result of surgery or postoperative complications. All patients were discharged from the hospital within 22 days (mean = 9.8 days). We conclude that exercise testing is a useful complement to conventional cardiopulmonary evaluation used in selecting patients for lung resection.

Aged↗
PubMed1992

Nodus migrans: the case of the migrating knot.

Flow-directed pulmonary artery catheters provide important information regarding intravascular volume status, cardiac function and vascular resistance. We describe an unusual complication of pulmonary artery catheterization in which a knot formed at the distal end was torn away from the catheter body and migrated from its original position in the right subclavian vein to a distal branch of the right pulmonary artery. Careful attention to insertion and withdrawal techniques could prevent this potentially serious complication.

Carcinoma, Small Cell↗
PubMed1992

Cardiac emergencies in the cancer patient.

Cardiac emergencies may be encountered during the management of patients with cancer, both in those with underlying cardiovascular disease and those with no previous history of cardiac problems. Both surgical and medical cancer treatment modalities may exacerbate preexisting cardiac conditions. Some antineoplastic agents can adversely affect the coronary arteries, myocardium, or pericardium. It has also been recognized that cardiac damage due to radiotherapy and chemotherapy may become clinically significant many years after therapy has been completed. Treatment of urgent cardiac problems in the cancer patient may differ from that recommended for other patient groups, since many cancer patients are not ideal candidates for some of the newer cardiac agents. Management of these conditions must therefore be tailored to the individual patient.

Emergencies↗
PubMed1991

Severe, symptomatic, dose-limiting hypophosphatemia induced by hepatic arterial infusion of recombinant tumor necrosis factor in patients with liver metastases.

Twenty-two patients with liver metastases received 45 courses of recombinant tumor necrosis factor (rTNF) by hepatic arterial infusion in doses ranging from 12.5 to 175 micrograms/m2/d for 5 days by continuous infusion. The induction of statistically significant, dose-related, severe, albeit transient, hypophosphatemia (less than 1.0 mg/dl) associated with clinically significant, right-sided myocardial dysfunction and severe lassitude was observed. These side effects were promptly reversed after rTNF was stopped and intravenous phosphate supplementation was started. As no significant or consistent increase in urinary phosphate excretion was detected, the rTNF-induced hypophosphatemia probably resulted from an intracellular shift of phosphate. Since tumor regression was clearly associated with the lowest levels of serum phosphate, hypophosphatemia may be important in the antitumor effects of rTNF.

Adult↗