Biomedical subjects

H Ibrahim

Publications and source records attributed to H Ibrahim.

At least 37 records · Page 2Linked to original sources

PubMed1995

Development of a melanin-based high-performance liquid chromatography stationary phase and its use in the study of drug-melanin binding interactions.

Drug-melanin interactions were studied using a melanin-based HPLC column. Two approaches were chosen for the preparation of the stationary phases: covalent coupling of synthetic L-dopa melanin and in situ polymerization of L-dopa. Retention of a series of phenothiazines on melanin-based stationary phases was attributed to binding to melanin. Frontal affinity chromatography experiments on one melanin-based column allowed us to calculate the affinity and binding capacity of chlorpromazine and promethazine. A competition was observed between chlorpromazine and haloperidol which was qualitatively consistent with previously described results. Data indicated that the interaction was not a simple competition at one site.

Antipsychotic Agents↗

PubMed1995

Stabilization of Octastatin, a somatostatin analogue. Preparation of freeze-dried products for parenteral injection.

Octastatin (RC-160, vapreotide INN) is a somatostatin analogue being developed for use in oncological, enterologic and neuroendocrine applications. The pharmaceutical form is a freeze-dried preparation for parenteral injection use. Three dosage forms containing 0.5, 1.5 and 15 mg of vapreotide base have been investigated. Various freeze-drying conditions, stabilizing agents, membranes for sterile filtration and heating procedures have been examined. The formulation with glutamic acid-sodium glutamate buffer as a stabilizing agent, the type of membrane for filtration and the freeze-drying procedure have been found appropriate for subsequent industrial production. No evident degradation was observed either after manufacturing, or after a three-week accelerated stability study at 50 degrees C and 70% relative humidity.

Amino Acid Sequence↗

PubMed1995

Effectiveness of a specialized asthma clinic in reducing asthma morbidity in an inner-city minority population.

Asthma is the most common chronic disease of childhood and a leading cause of morbidity in adults. Despite significant advances in medical therapy, asthma morbidity and mortality rates have risen dramatically over the past two decades, especially in minority and socioeconomically disadvantaged populations. Numerous intervention programs have been designed in an attempt to reduce asthma morbidity but few have targeted poor or minority populations. The purpose of this study was to assess whether an outpatient intervention program specifically targeted at a high-minority population in East Harlem, in New York City, was successful in reducing asthma morbidity. A retrospective chart review of 84 patient records was conducted. The patients were divided into two groups, an intervention group (n = 45), who were followed by an asthma specialist (allergist/immunologist), and a nonintervention group, followed by a general internist or pediatrician. Outcome variables including clinic walk-in visits, emergency room visits, and hospitalizations were determined and compared in the pre- and postintervention period in both groups. Patients in the intervention group had reduced total walk-in visits (73 vs. 27, p < 0.001), emergency room visits (30 vs. 5, p < 0.001), and hospitalizations (16 vs. 2, p < 0.001). In contrast, patients in the nonintervention group had no change in total walk-in visits (88 vs. 72), increased emergency visits (7 vs. 22, p < 0.05), and no change in hospitalizations (5 vs. 2), respectively. The outpatient intervention program has been successful in reducing asthma morbidity in the high-risk minority community of East Harlem. Future larger studies are warranted to extend this pilot program to other high-risk minority populations.

Adolescent↗

PubMed1994

Erythropoietin (EPO) levels in fetal rats after ritodrine and terbutaline administration.

Beta-2 sympathomimetics, such as terbutaline, have been shown to alter erythropoietin (EPO) secretion in animal studies. More recently introduced sympathomimetics, such as ritodrine, have been extensively used to inhibit uterine contractions in preterm labor. It has not been determined what effect ritodrine may have on EPO production. We investigated the effect of RD administered to rats in the last day of gestation on the dam and the fetuses' levels of EPO. Rats at the 20th day of gestation were given, under anesthesia, either 3000 micrograms/kg ritodrine over a 10-min period or a similar volume of saline as control (CTL). Fetuses were removed at 0 and 4 h after injection. Ritodrine administration produced a decrease of dam EPO (23.4 +/- 4.2 to 12.0 +/- 2.9 pmol/ml), while the CTL showed no changes. The fetuses from the ritodrine-injected dams exhibited a marked decline over the 4-h period, while the CTL fetuses did not change. In other experiments 500 micrograms terbutaline was administered daily during the last 5 days of rat gestation. The drug produced a significant decline in EPO at delivery time, but plasma EPO in the pups was unchanged. Blood hematocrits were comparable to those of controls. The data show that acute administration of ritodrine reduces fetal and dam plasma EPO, while long-term terbutaline treatment late in gestation alters maternal, but not fetal plasma EPO, indicating that neither drug has any direct regulatory effect on the erythropoietic ability of the fetuses.

Animals↗

PubMed1994

[Hemodynamic diagnosis of aortocaval fistula complicating abdominal aortic aneurysm].

A 78-year-old man with a history of hypertension was admitted for a fall with back pain. The blood pressure was at 110/50 mmHg and the pulse at 115 b.min-1. A pulsatile abdominal mass was palpated. No signs of respiratory insufficiency or congestive heart failure were found. The diagnosis of abdominal aortic aneurysm was promptly confirmed by echography. Before laparotomy, a pulmonary artery catheter was inserted for haemodynamic monitoring which showed a high cardiac output, low systemic vascular resistances, increased pulmonary artery wedge pressure and a high SvO2 (93%). This was not consistent with a hypovolaemic shock but rather an aortocaval fistula. After incision and aortic clamping, surgical procedure consisted of transaortic closure of the fistula and restoration of arterial continuity with a prosthetic graft. Initial control of venous bleeding was obtained by passing a Foley's catheter distally and by clamping the vena cava. The postoperative course was initially satisfactory. The patient was extubated, but remained with a major renal insufficiency. After a stay of 15 days in the intensive care unit, he died from nosocomial pneumonia. Aortocaval fistulas are either traumatic or spontaneous. Spontaneous fistulas are more common, and in about 90% of the cases result from a rupture of an atherosclerotic aortic aneurysm. Clinical findings include signs of high cardiac output symptoms of venous hypertension and regional arterial insufficiency. Haemodynamic changes can be of value for the recognition of an aortocaval fistula. Most authors emphasize the importance of preoperative diagnosis, allowing the use of appropriate operative techniques and a prompt control of the fistula. This could decrease haemodynamic instability and transfusion requirements.

Aged↗

PubMed1993

Albendazole therapy of hydatid disease: 2-year follow-up of 40 cases.

Forty patients with 63 Echinococcus granulosus cysts affecting different sites were treated with albendazole and have been followed up for at least 24 months from completion of therapy. Twenty-one patients (53%) with 37 cysts (59%) showed evidence of healing. The criteria and pattern of healing are outlined. The most serious complication of albendazole therapy was hepatoxic jaundice, which occurred in 5% of patients. Recurrence during the observation period was encountered in 9.5% of patients with a positive response. It is suggested that patients suffering from uncomplicated hydatid disease should be given the benefit of a trial course of albendazole therapy, before surgery is undertaken.

Adolescent↗

PubMed1993

Coronary collateral circulation in the transplanted heart.

BACKGROUND: The concept that coronary collateral (CC) circulation can develop in cardiac transplant recipients (CTR) is controversial. Indeed, a decreased occurrence of CC in CTR has been previously reported. METHODS AND RESULTS: We reviewed 102 coronary angiograms in 73 CTR to evaluate the presence and significance of CC in denervated human hearts. These angiograms were compared with angiograms of 70 nontransplanted patients. Twenty-six CTR who had undergone at least two coronary angiograms, thus allowing comparative evaluations, form the basis for this study. Angiograms were analyzed using a modification of CC classification (Rentrop et al) from grade 0 for complete absence to grade 4 representing mature collateral with clear filling of epicardial vessels. Coronary artery disease was classified according to the scheme reported by Gao et al. For the purpose of this study, all type A lesions were grouped as large vessel disease (LVD), and types B1, B2, and C were collectively grouped as small vessel (epicardial) disease (SVD). The presence of CC circulation in all 73 CTR was grade 0, 7 (10%); grade 1, 41 (56%); grade 2, 33 (45%); grade 3, 30 (41%); and grade 4, 5 (7%). However, in control nontransplanted subjects grades 0, 1, 2, 3, and 4 were found in 47 (67%), 22 (31%), 4 (6%), 11 (15%), and 16 (20%) patients, respectively. The presence of mature collaterals (grade 4) in both groups were associated with type A lesions and was frequent in nontransplanted hearts. In contrast, grade 2 and grade 3 vascular channels probably representing CC with "myocardial blush" was more frequent in CTR and was mostly associated with small vessel coronary arteriopathy. CONCLUSIONS: These results suggest the presence of atypical CC in patients with cardiac allograft arteriopathy. It is speculated that this atypical form of CC with "blush pattern" may represent an angiogenic response to microvascular ischemia due to allograft coronary arteriopathy.

Adult↗

PubMed1992

Desmopressin has no beneficial effect on excessive postoperative bleeding or blood product requirements associated with cardiopulmonary bypass.

Cardiopulmonary bypass during open-heart surgery is sometimes associated with excessive perioperative bleeding. Following a non-randomized study suggesting that desmopressin acetate (desmopressin) reduced blood product requirements in these patients, we conducted a double-blind, placebo-controlled randomized trial of desmopressin (0.3 micrograms/kg, i. v.) in 92 patients with overt bleeding and a prolonged bleeding time. Mean blood loss during the first 24 h post-treatment was similar in the desmopressin and placebo groups (582 vs 465 ml, respectively; p = 0.15). Red-cell (p = 0.76), fresh frozen plasma (r = 0.66) and platelet unit (p = 0.74) requirements were also similar. The haemostatic effect of desmopressin has been attributed to the release of von Willebrand factor (vWF) and a reduced bleeding time. In our study, vWF and factor VIII:C levels increased while the bleeding time decreased significantly at 90 min and 24 h in both groups and, although vWF and factor VIII:C levels were slightly higher in desmopressin-treated patients at 90 min, the difference was not significant. Thrombin-antithrombin III complex, fibrinogen degradation product and tissue plasminogen activator levels, reflecting activation of the coagulation and fibrinolytic systems, respectively, decreased uniformly in both groups. We conclude that desmopressin is not useful in reducing blood loss or blood product requirements in patients with excessive immediate postoperative bleeding.

Adolescent↗

PubMed1991

A thyroid testing algorithm: results of a pilot study.

We conducted a pilot study to evaluate an algorithm for thyroid function testing consisting of initial serum thyrotropin values, measured by a sensitive immunoradiometric assay (TSH-IRMA), followed by a computer-directed decision to order further studies. We divided 216 outpatients according to their serum TSH-IRMA values as follows: suppressed (less than 0.1 mU/L, group I); low (0.1 to 0.4 mU/L, group II); normal (0.5 to 5.0 mU/L, group III); and high (greater than 5.0 mU/L, group IV). Thyroxine (T4), resin uptake (RU), and free thyroxine index (FTI) tests on groups I, II, and IV revealed that T4 and RU were normal for most patients in all groups and FTI was normal in 80% of group I, 93.4% of group II, and 93.3% of group IV. All patients in group I were designated hyperthyroid from either an exogenous or endogenous source. All patients in group II were clinically euthyroid except one; 50% were taking either L-thyroxine or propylthiouracil and 50% had no identifiable thyroid disease. Patients in group IV were hypothyroid. Overall, TSH was more effective in detecting both hypothyroidism and hyperthyroidism than either serum T4, RU ratio, or both combined in FTI since results of these measures fell in the normal range for most patients in all groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Algorithms↗

PubMed1989

Detection of sleep associated dysfunctional pharyngeal obstruction in infants.

Six infants were referred with symptoms and clinical signs suggesting airway obstruction during sleep. In each case, overnight recordings of arterial oxygen saturation, respiratory movements and end tidal expired carbon dioxide (ETCO2) showed the presence of abnormal episodes of hypoxaemia related to partial or complete airway obstruction and associated with a specific pattern of the inspiratory movement waveforms. These events and patterns were not found on recordings from 20 age-matched healthy infants and young children. ETCO2 levels were also abnormally elevated in all six patients when asleep. Fiber-optic upper airway endoscopy excluded structural abnormalities, including significant tonsillar or adenoidal enlargement, but showed an intermittent dysfunctional inspiratory obstruction in the pharynx. Continuous positive airways pressure and tracheostomy were effective in treating this obstruction.

Airway Obstruction↗

PubMed1989

[Block of the superior laryngeal nerve for ORL endoscopy. Description of a simplified technique].

The usual anterior and lateral routes used for superior laryngeal (SL) nerve blocks are not often used because too difficult to carry out. A simpler and easier technique is described, which blocks the SL nerve at the level of the greater cornu of the hyoid bone. Because the nerve is not located accurately with this technique, a larger volume of local anaesthetic is required. This technique was tested in 31 patients scheduled for endoscopies with rigid tubes. The mean duration of endoscopy was 30 +/- 10 min. The use of 8 ml 1% lidocaine for the block 30 min surgical anaesthesia. In 2 patients, the SL nerve block alone was sufficient. In 26 others a complement with a benzodiazepine (flunitrazepam, n = 9, mean dose 0.8 mg; midazolam, n = 17, mean dose 5 mg) was required. In 4 of these patients, attempts of oesophagoscopy gave rise to hypertension and tachycardia. General anaesthesia with propofol and tracheal intubation were therefore used. In the last 3 patients, intercricothyroid jet ventilation was used, requiring general anaesthesia (propofol and succinylcholine). The SL nerve block was satisfactory in 24 patients with total vocal cord paralysis and no haemodynamic reaction to painful stimuli in the blocked area. No complication was observed. It is concluded that this technique is useful and easier to carry out than the usual ones.

Anesthesia, General↗

PubMed1989

A bioequivalence study of two dipyridamole products.

Bioequivalence of Antiplate 75 mg was assessed versus Persantine 75 mg in a two-way crossover study. At the 5% confidence level, no significant difference was found between the area under the plasma concentration-time curves of the two products. The Cmax were comparable for both products. Quality control data including assay, content uniformity, disintegration and dissolution indicated that both products passed the pharmacopoeial requirements, USP XXI and BP 1980, Addendum 1983. It is concluded that Antiplate-75 is bioequivalent to Persantine.

Adult↗

PubMed1988