Biomedical subjects

H Taheri

Publications and source records attributed to H Taheri.

9 recordsLinked to original sources

PubMed2002

Effect of Helicobacter pylori eradication or of ranitidine plus metoclopramide on Helicobacter pylori-positive functional dyspepsia. A randomized, controlled follow-up study.

BACKGROUND: A definitive treatment for functional dyspepsia (FD), and the role of Helicobacter pylori eradication on the course of this disease are controversial. AIM: To investigate the effect of a combination of acid-suppressing and prokinetic drugs or eradication therapy on the course of H. pylori-positive FD. METHOD: A total of 157 patients with endoscopically-proven H. pylori-positive FD and no response to 4 weeks of antacid therapy were randomly divided into 2 groups. 84 were placed on bismuth subnitrate plus metronidazole and amoxicillin (group A) and 73 received ranitidine and metoclopramide for 4 weeks (group B). The severity of symptoms (7 items) were assessed on a 6-point categorical scale. Group B patients who failed to respond to their medication underwent eradication therapy after 3 months. All patients were followed and assessed for 9 months after the end of therapy by the same clinicians who initiated the therapy. RESULTS: At the end of the medication period, symptom's score decreased significantly, and to the same extent. At 3-month follow-up moderate or complete response was achieved in 27.4% (group A) and 19.2% (group B) by intention-to-treat analysis. 34 patients of group B, not responding to treatment, underwent eradication therapy and followed as group A. Eradication of H. pylori was successful in 60 of 110 controlled patients (54%). After 9-month follow-up, complete or moderate response was observed in only 30% of 60 patients in whom H. pylori had been eradicated (intention-to-treat analysis), compared to 38% in 50 noneradicated cases (p > 0.05, 95% CI: 19-43 vs. 24-52). CONCLUSION: Eradication therapy with bismuth compound is effective as ranitidine plus metoclopramide in a subgroup of patients with FD not responding to antacid therapy. There is no difference in improvement between patients cured or not cured from H. pylori infection. This suggests that bismuth compounds were effective in FD when used in the eradication regimen. Combination therapy with acid-suppressing drugs plus prokinetic and bismuth seems to hold promise for FD.

Adult↗

PubMed2001

Cyclosporin A is a promising alternative to corticosteroids in autoimmune hepatitis.

Autoimmune hepatitis (AIH), a chronic T-cell-mediated liver injury, is treated with corticosteroids with or without Azathioprine. Corticosteroids are not universally effective and have serious side effects. Cyclosporin A was effective in refractory cases. To assess efficacy and safety of Cyclosporin A (Neoral) in induction of remission in AIH patients this study was performed. Nineteen consenting AIH patients (nine treatment-naive) were treated with cyclosporin A in an open label trial and followed for 26 weeks. Liver biopsy was done and hepatitis activity index (HAI) determined at the beginning and end of treatment. Four patients did not complete the study for various reasons. Mean AST and ALT levels decreased from 948.7 +/- 103.5 and 454.8 +/- 354 to 100.6 +/- 111.8 and 78.5 +/- 40.3 (P < 0.03, P < 0.001) respectively. HAI decreased from 15.2 +/- 3.16 to 7.14 +/- 4.01 (P < 0.005). Serum creatinine did not change significantly. In conclusion, low-dose cyclosporin A appears to be safe and effective even in treatment-naive autoimmune hepatitis patients. Randomized controlled trials are warranted.

Adolescent↗

PubMed2000

Using coronary calcification scanning in the clinical practice of preventive cardiology.

Preventive therapies such as cholesterol reduction significantly reduce the risk of acute coronary events. Diagnostic tools that identify asymptomatic coronary atherosclerosis would permit initiation of aggressive preventive therapies at an earlier stage of coronary disease. Histologic and angiographic data demonstrate that coronary calcium has a very high sensitivity for the presence of coronary plaque. Therefore, coronary calcification can be regarded as a marker for coronary atherosclerosis. Coronary calcium scanning has been suggested as a tool for identification of a high-risk asymptomatic patient group. It can be utilized to guide the aggressiveness of risk factor modification and therapeutic preventive interventions toward those at higher risk for future events. Based on the available data, we review the clinical use of coronary calcium scanning in preventive cardiology.

Calcinosis↗

PubMed1997

MHC class II genes influence the susceptibility to chronic active hepatitis C.

BACKGROUND/AIMS: Chronic hepatitis C develops in more than 70% of hepatitis C virus infected subjects. Viral factors influence the disease course, but little is known about the importance of host factors. METHODS: Frequencies of major histocompatibility complex (MHC) class I and class II antigens were analyzed in two groups of patients with chronic hepatitis C virus infection and in control subjects. MHC class I typing was done by standard microlymphocytotoxicity assays. DRB1 and DQA1 genotyping was done by PCR based typing methods. RESULTS: DRB1*0301 was found in 26 of 75 patients with chronic hepatitis C virus infection (34.7%) and in 12 of 101 control subjects (11.9%) (relative risk 3.9; p < 0.001). Homozygosity for this allele appeared to confer a stronger risk. In contrast, DRB1*1301 was detected in three subjects with persistent infection (4.0%) compared to 21 control subjects (20.8%) (relative risk 0.2; p < 0.008). This allele was linked with DQA1*0103, which was found in 10 patients (13.3%) compared to 34 control subjects (33.7%) (relative risk 0.31; p < 0.003). An even stronger protective effect was provided by the presence of DRB1*1301 and DQA1*0103 (relative risk 0.08; p < 0.005). These findings were confirmed in a second group of chronic hepatitis C virus infected patients. CONCLUSIONS: The MHC class II allele DRB1*0301 appears to predispose to progression to chronic active hepatitis C, whereas the class II alleles DRB1*1301 and DQA1*0103 appear to provide protection against chronic active infection with hepatitis C virus.

Alleles↗

PubMed1997

HLA-DRB11301 and 1302 protect against chronic hepatitis B.

BACKGROUND/AIMS: The outcome of acute hepatitis B infection may be influenced by host factors like the major histocompatibility complex (MHC). We have investigated MHC class I and class II antigens in patients with chronic hepatitis B compared to a healthy control population. To confirm the findings of this first study we performed a second study in a group of subjects who had spontaneously recovered from acute hepatitis B infection. METHODS: Frequencies of MHC class I and class II antigens were analyzed in patients with chronic hepatitis B virus infection and in control subjects. MHC class I typing was done by standard microlymphocytotoxicity assays. DRB1 and DQA1 genotypes were determined by polymerase chain reaction based typing methods. RESULTS: In the first study the class II allele HLA-DRB1*1301-02 was found in 4 of 70 subjects with chronic hepatitis B virus infection (5.7%) compared to 27 of 101 healthy controls (26.7%, relative risk 0.17; p=0.001; p(corr)=0.025). This protective effect of the DRB1*1301-02 allele was confirmed in the second study. Eight of 24 patients (33.3%) who cleared hepatitis B virus spontaneously were positive for DRB1*1301-02 (relative risk of developing chronic infection compared to chronic hepatitis B subjects 0.12; p=0.004). Subtyping confirmed that 1301 and 1302 were both decreased in frequency in patients with chronic hepatitis B. CONCLUSIONS: The MHC class II allele DRB1* 1301-02 is associated with protection from chronic hepatitis B in Caucasian patients.

Adult↗

PubMed1994

Series coupled non-contractile elements are functionally unimportant in the isolated heart.

OBJECTIVE: In order to evaluate possible artefact in interpretations of contractile behaviour in isolated heart experiments, the relative elastances of series coupled non-contractile and contractile components of the left ventricle of the isolated heart were evaluated. METHODS: Hearts were isolated from ferrets and rabbits and mounted on a servo-controlled volume regulation device. These hearts were made to beat isovolumetrically until a selected volume perturbation was introduced. Constant flow volume withdrawals at two flow values were performed over a period of < 20 ms centred around the time of peak isovolumetric pressure. Three levels of isovolumetric pressure were produced using basal, extrasystolic, and potentiated beats. Pressure responses to volume withdrawals at two flows and three isovolumetric pressures were then analysed using a mathematical model to evaluate relative values of series coupled contractile and non-contractile elastances. To validate the analysis procedure, a non-contractile series artefact with known elastance was coupled to the left ventricle; volume perturbations were then applied to the coupled left ventricle-artefact system; responses were analysed and the estimate of series coupled non-contractile elastance was compared to the known elastance of the added artefact. RESULTS: A wide range of isovolumetric pressures [208(SD 40) mmHg] was produced in the ferret with basal, extrasystolic, and potentiated beats. A lesser range of isovolumetric pressures [50(15) mmHg] was produced in the rabbit. The mathematical model fitted the data very well in both the ferret and rabbit. The elastance of the series coupled non-contractile component could be estimated only in some ferrets. When estimated in the ferret, the elastance of the series coupled non-contractile component was never less than 4x that of the contractile component. When a series artefact of sufficiently low value was coupled with the native left ventricle, the elastance of the non-contractile component could be reliably estimated in both ferrets and rabbits and the estimated value approximated that of the added artefact. This indicated that the elastance of the series coupled non-contractile component of the native left ventricle was much higher than that of the added artefact. CONCLUSIONS: The series coupled non-contractile component of the isolated heart possesses a very much higher elastance than the contractile component. In fact, the elastance of the non-contractile component is so great that it contributes very little to the dynamic behaviour of the left ventricle. Virtually all of the elastance of the left ventricle of the isolated heart is due to the contractile component.

Animals↗

PubMed1993

Similarities between dynamic elastance of left ventricular chamber and papillary muscle of rabbit heart.

The frequency-dependent dynamic elastance of the left ventricle (LV) of isolated rabbit heart was determined and compared with dynamic stiffness of excised rabbit papillary muscle. Comparison was made in three states: 1) relaxed, 2) BaCl2 contracture, and 3) rigor. Dynamic chamber elastance was determined by pressure-to-volume ratio at 12 frequencies of sinusoidal volume variation between 0.1 and 30 Hz. Dynamic elastance during BaCl2 contracture was distinctly different from that during either relaxed or rigor states. Characteristics of BaCl2 contracture were 1) as frequency increased, polar plot of real and imaginary elastance showed a progressively opening clockwise spiral that tended eventually to become tangent to the apogee of a semi-circle by 30 Hz; 2) modulus spectrum exhibited asymptotes at low and high frequencies with an intervening dip to a minimum at 1.25 Hz; and 3) phase showed a sharp transition at dip frequency from small negative values at lower frequencies to large positive values at intermediate frequencies and then declined at highest frequencies. There was little dependence of dynamic elastance on frequency in both relaxed and rigor states. Dynamic muscle stiffness exhibited all features of dynamic chamber elastance in all three states. We concluded that dynamic elements responsible for myofiber stiffness were also responsible for LV chamber elastance. Furthermore, it was possible to describe and interpret dynamic chamber elastance and muscle stiffness with a common model based on muscle cross-bridge theory. This model did a reasonable job of reproducing all important features of experimentally observed LV chamber elastance and muscle stiffness. Thus dynamic homologies between chamber and muscle were established in experimental data and in the fact that a single interpretive model served equally well for both chamber elastance and muscle stiffness.

Animals↗

PubMed1992

Single perturbed beat vs. steady-state beats for assessing systolic function in the isolated heart.

Single-beat and steady-state techniques for evaluating end-systolic pressure-volume relationship (ESPVR) and Frank-Starling mechanism (FSM) in the crystalloid-perfused isolated rabbit heart were compared. In the single-beat technique, a train of stable isovolumic beats was interrupted with a single perturbed beat that either ejected against various levels of imposed isobaric load (ESPVR protocol) or beat isovolumically against various levels of end-diastolic volume (V(ED); FSM protocol). In steady-state technique, sustained beating was established, isobarically, at each of various loads (ESPVR protocol) or, isovolumically, at each of various V(ED) values (FSM protocol). ESPVR from steady-state technique lay above and to the left of that from single-beat technique. Contractile state was not uniform within steady-state technique, whereas it was uniform within single-beat technique. In the FSM protocol, single-beat technique exhibited the following features relative to steady-state technique: 1) greater range of developed pressures, 2) steeper ascending limb and more sharply defined maxima, 3) higher maximal developed pressure (Pdmax), and 4) greater volume at Pdmax(Vmax). Again. a common contractile state existed within single-beat technique but not within steady-state technique. It was concluded that single-beat technique was preferable to steady-state technique for evaluating ESPVR and FSM because 1) single-beat technique required less time for obtaining data, 2) single-beat technique allowed identification of uncomplicated values of Pdmax and Vmax, and 3) single-beat technique provided a common contractile-state reference for all data, whereas steady-state technique did not.

Animals↗

PubMed1991

Method for studying arterial wave transmission effects on left ventricular function.

A technique for studying the real-time effects of arterial wave reflections on the performance of the isolated left ventricle was investigated. Real-time arterial loading of an isolated ferret heart with an asymmetric T-tube wave transmission model was obtained with the use of a multiprocessor computer control system and a volume control linear motor pump. The multiprocessor computer system was programmed to compute the instantaneous aortic flow from the instantaneous ventricular pressure. The time integral of the flow was used as a command to the linear motor pump to control the instantaneous ventricular volume. This loading system allowed the imposition of a wide variety of vascular impedances on the ventricle by changing the parameters of the asymmetric T-tube model.

Animals↗