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Biomedical subjects

M N Alam

Publications and source records attributed to M N Alam.

At least 37 records · Page 2Linked to original sources
PubMed1997

Thermosensitive neurons of the diagonal band in rats: relation to wakefulness and non-rapid eye movement sleep.

The thermosensitivity of the neurons in the diagonal band of Broca (DBB) was studied in 12 freely moving rats by determining responses to local cooling or warming with a water perfused thermode. Of 151 neurons studied, 37 (25%) neurons met the criterion for thermosensitivity including 17 warm-sensitive (WSNs) and 20 cold-sensitive neurons (CSNs). The spontaneous discharge rates of WSNs and CSNs were recorded through 1-3 sleep-waking cycles. The discharge of WSNs and CSNs during waking and non-rapid eye movement (NREM) sleep were different. Of 17 WSNs, 10 exhibited increased discharge rates during NREM sleep as compared with waking (NREM/Wake discharge ratio, > 1.2). Of 20 CSNs, 14 discharged more slowly during NREM sleep as compared with waking (NREM/Wake discharge ratio, < 0.8). In both WSNs and CSNs, changes in discharge rate preceded EEG changes at the waking-NREM transition. These results support a hypothesis that the activation of sleep-related WSNs and the deactivation of wake-related CSNs play a role in the onset and regulation of NREM sleep.

Animals↗
PubMed1997

Radioactivity in sediments of the Karnaphuli river estuary and the Bay of Bengal.

Sediment samples from the Karnaphuli river estuary, nearshore, and off-shore regions off the coast of Chittagong in the Bay of Bengal were analyzed for the natural radioactivity contents of 232Th, 238U and 40K and anthropogenic radioactivity contents of 137Cs and 134Cs using HPGe gamma spectrometry, together with the measurement of sediment pH and grain size analyses of the collected samples. The activity of 232Th found in sediment ranged from 10.44 +/- 2.31 to 64.02 +/- 8.13 Bq kg(-1), 238U activity ranged from 5.87 +/- 1.21 to 27.85 +/- 1.71 Bq kg(-1), 40K activity from 118.28 +/- 19.70 to 608.21 +/- 75.70 Bq kg(-1), and the activity 137Cs ranged from 0.09 +/- 0.06 to 4.64 +/- 0.19 Bq kg(-1), no 134Cs radioactivity was detected at any of the sampling stations.

Geologic Sediments↗
PubMed1997

Value of clinical features in the diagnosis of enteric fever.

There is no objective data on the value of individual clinical symptoms or signs in the diagnosis of enteric fever in a febrile patient. The purpose of the study was to assess the value of some clinical and simple laboratory features in the diagnosis of enteric fever. One hundred & six patients with microbiologically confirmed enteric fever and 170 patients with other established febrile illnesses were included in the evaluation. History of stepladder pattern of rise of temperature, loose motions, relative bradycardia and coated tongue proved to be powerful markers of enteric fever with high specificity (100%, 94.71%, 94.71%, 94.12% respectively), positive and negative predictive values. Headache, hepatomegaly and splenomegaly were moderately powerful. ESR and WBC count appeared to have little value in the diagnosis of enteric fever. Pattern of onset and loose motions did not discriminate between typhoid and paratyphoid fever. Most of these patients had illness persisting beyond one week by which viral infections and infectious enterocolitides were largely excluded. Elucidation of power of these markers in distinguishing enteric fever from other febrile illnesses with the help of better designed prospective studies would lessen our dependence on expensive and time consuming laboratory investigations.

Adolescent↗
PubMed1997

Efficacy of methotrexate in rheumatoid arthritis.

Rheumatoid arthritis is a common inflammatory articular disorder in Bangladesh. Methotrexate has proved to be an effective and relatively safe disease modifying drug for this disease. A quasiexperimental trial of the efficacy of methotrexate in rheumatoid arthritis was carried out in the Rheumatology Clinic, Institute of Postgraduate Medicine & Research, Dhaka during the period between July 1992 and September 1993. Thirty eight patients fulfilling the revised ARA criteria were given methotrexate in a total weekly dose of 7.5 to 15 mg. They were followed up at weekly intervals for one month and then monthly for a total duration of six months. Twenty three subjects eventually completed the trial. The trial showed significant differences in the disease activity indices at the end of six months. The decline of activity was noted at the end of one month. As a whole the response was complete in 4(17%), marked in 14(61%), moderate in 4(17%) and nil in 1(4%). Adverse effects occurred in 27 subjects. They were mild and transient in 22. Methotrexate appeared to be an acceptable DMARD for our rheumatoid arthritis population.

Adult↗
PubMed1996

Preoptic/anterior hypothalamic neurons: thermosensitivity in wakefulness and non rapid eye movement sleep.

Thermosensitive neurons of the preoptic/anterior hypothalamic area (POAH) have been implicated in the regulation of both body temperature and non rapid eye movement (NREM) sleep. During NREM sleep, a majority of POAH warm-sensitive neurons (WSN) exhibit increased discharge compared to wakefulness. Cold-sensitive neurons (CSN) exhibit reduced discharge in NREM sleep compared to wakefulness. To further study the mechanism underlying these processes, the present study compared discharge rate and thermosensitivity (discharge rate change/degree C) of WSNs and CSNs in NREM sleep and wakefulness in freely moving adult cats. The thermosensitivity of 24 WSNs and 31 CSNs from the medial POAH was determined from responses to local POAH warming and cooling. WSNs with increased discharge in NREM sleep exhibited increased thermosensitivity during NREM sleep compared to wakefulness. CSNs with decreased discharge during NREM sleep exhibited decreased thermosensitivity in NREM sleep. The change in thermosensitivity from wakefulness to NREM sleep was correlated with the change in discharge rate in WSNs but not in CSNs. In addition, 9 of 47 neurons that were thermo-insensitive during wakefulness became warm-sensitive during NREM sleep. Changes in POAH neuronal thermosensitivity could be a component of the mechanism for stabilization of state after state transition.

Animals↗
PubMed1996

Solitary thyroid nodule: a study of 100 cases.

One hundred cases of solitary thyroid nodules attending the thyroid clinic, Institute of Postgraduate Medicine & Research, Dhaka (IPGMR) and the Institute of Nuclear Medicine (INM) were included in a prospective study. Thyroid ultrasonography (USG), scintiscanning, radioactive iodine (I131) uptake (RAIU), estimation of serum total T3, T4 & TSH and Fine Needle Aspiration Cytology (FNAC) were performed in all cases. Surgical resection with histopathologic study was performed in selected cases. Extra-nodular part of the thyroid gland was normal in 68 and diffusely enlarged in 32, RAIU was normal in 62, high in 36 and very low in two subjects. Nodules were solid at USG in 67 subjects, cystic in 16 subjects and of mixed consistency in 17 subjects. Goitrous subjects had significantly lower T4 (p < 0.001) and higher T3 (p < 0.01) and TSH (p < 0.001) than non-goitrous ones. Colloid nodule was the commonest pathology occurring in 41 cases, followed by thyroid cysts (26), follicular adenoma (23), adenoma with cystic change (7), subacute thyroiditis (2) and papillary carcinoma (1). Colloid nodules were more common in goitrous subjects which could hint at iodine deficiency as the major cause of such nodules. Hyperfunctioning follicular adenomas occurred exclusively in non-goitrous subjects. Carcinoma appeared to be uncommon in patients with solitary nodules. It gives an opportunity to our physicians to be more conservative in selecting patients with solitary thyroid nodules for surgical treatment.

Adenoma↗
PubMed1996

A study of prolonged pyrexia in Dhaka.

In a prospective study conducted in the Institute of Postgraduate Medicine & Research (IPGMR), Dhaka, 212 patients with prolonged pyrexia were thoroughly evaluated clinically and with the help of laboratory investigations with a view to reaching the diagnosis. Their clinical and laboratory data were recorded. Clinical features pertaining to a particular organ gave appropriate clue in 52% cases. Imaging techniques were instrumental in 24%, microbiological or serological investigations in 35%, invasive procedures were diagnostic in 42%, laparotomy had to be resorted to in five cases. Infectious diseases were the commonest causes of prolonged pyrexia accounting for about 63.21% of cases followed by neoplasms (12.74%) and connective tissue disorders (10.85%). Tuberculosis was the most common infection (24.53% of all cases) followed by enteric fever (12.74%) and visceral leishmaniasis (9.43%). Pleura was the commonest seat for tuberculosis followed by lymph nodes and abdomen. Leukemias were the commonest neoplasm and SLE the commonest connective tissue disorder presenting with prolonged fever. Several fundamental observations were made in the study. Infections are the commonest cause of prolonged fever in our community, neoplasms and connective tissue disorders are also not rare. Secondly, patients with temperature between 100 to 101 degrees F should not be denied evaluation with the apprehension of unnecessarily investigating for habitual hyperthermia, as the condition was distinctly rare in the series. Thirdly, analysis of materials from organs or systems suspected to be abnormal clinically or by simple imaging techniques had high diagnostic yield. Finally, usual causes of prolonged fever are illnesses ordinarily encountered in clinical practice, pyrexia becomes protracted either because the presentation is atypical or incomplete, or because we fail to make proper use of available clinical or paraclinical information.

Adolescent↗
PubMed1995

Radioactivity in marine fish of the Bay of Bengal.

The concentrations of natural radionuclides of 40K, 232Th and 238U and artificial radionuclides of 137Cs and 134Cs in different marine fish samples from the Bay of Bengal were determined. In some of the fish samples contamination of the 137Cs radionuclide was observed, but 134Cs was below detection level.

Animals↗
PubMed1995

Neuronal discharge of preoptic/anterior hypothalamic thermosensitive neurons: relation to NREM sleep.

Thermosensitive neurons of the preoptic/anterior hypothalamic area (POAH) have been implicated in the regulation of non-rapid eye movement (NREM) sleep. We attempted to identify those medial POAH thermosensitive neurons that may be involved in NREM sleep regulation. The thermosensitivity of medial POAH neurons was studied in five freely moving adult cats by local cooling or warming of the medial POAH with a water-perfused thermode. Of 308 neurons, 65 (21%) were classified as thermosensitive, including 31 (10%) warm-sensitive and 34 (11%) cold-sensitive neurons. The spontaneous discharge rates of 28 warm-sensitive, 34 cold-sensitive, and 115 randomly selected thermoinsensitive neurons were recorded through one to three sleep-waking cycles. Patterns of spontaneous activity for warm- and cold-sensitive neurons were different. Of 28 warm-sensitive neurons, 18 (64%) exhibited increased discharge rate during NREM sleep compared with waking (NREM/wake, > or = 1.2). This subpopulation of warm-sensitive neurons also exhibited significantly increased thermosensitivity when tested during NREM sleep. Of 34 cold-sensitive neurons, 25 (74%) discharged more slowly during NREM sleep compared with waking (NREM/wake, < or = 0.8). This subpopulation of cold-sensitive neurons exhibited decreased thermosensitivity during NREM sleep. These results are consistent with a hypothesis that the activation of sleep-related warm-sensitive neurons and the deactivation of wake-related cold-sensitive neurons may play a key role in the onset and regulation of NREM sleep.

Animals↗
PubMed1995

Preoptic/anterior hypothalamic neurons: thermosensitivity in rapid eye movement sleep.

The thermosensitivity of 15 warm-sensitive neurons (WSNs) and 19 cold-sensitive neurons (CSNs) from the medial preoptic/anterior hypothalamus (POAH) was tested during wakefulness, non-rapid eye movement (NREM) sleep and rapid eye movement (REM) sleep by local POAH warming and cooling in freely moving cats. Thermosensitivity was quantified by three criteria, Q10, impulses per second per degree Celsius, and percent change per degree Celsius. Irrespective of the criterion used, WSNs did not exhibit a significant change in thermosensitivity during REM sleep compared with wakefulness and NREM sleep. In contrast, CSNs exhibited decreased mean thermosensitivity during REM sleep compared with wakefulness. CSNs as a group did not retain significant thermosensitivity in REM sleep. These findings are consistent with evidence that thermoeffector responses to cooling are lost in REM sleep, whereas some responses to warming are preserved.

Animals↗
PubMed1995

Efficacy of ciprofloxacin in enteric fever: comparison of treatment duration in sensitive and multidrug-resistant Salmonella.

The efficacy of two regimens of ciprofloxacin was compared in a randomized study conducted on 69 patients with enteric fever, 52.2% of whom had infection with multidrug-resistant (MDR) strains of Salmonella typhi or S. paratyphi. Patients were randomly assigned to two regimens (10 days versus 14 days) of ciprofloxacin (500 mg twice a day). The mean +/- SD time required for defervescence was similar for both regimens (4.2 +/- 1.9 days in the 10-day group and 4.9 +/- 2.6 days in the 14-day group). A 100% cure was observed in each treatment group and no serious side effects were observed. Relapse occurred in two patients (14-day regimen). Only one patient (14-day regimen) had growth of S. typhi in stool culture at the time of the first follow-up three days after completion of therapy. Follow-up studies on available patients on two, six, and 12 months after completion of therapy revealed that all patients had negative stool cultures for S. typhi and S. paratyphi. This study indicates that ciprofloxacin may be recommended as an initial therapy for enteric fever for adult men and nonpregnant and nonlactating women in areas where MDR strains of S. typhi and S. paratyphi are prevalent, and that 500 mg twice a day of the drug given for 10 days is as effective as 14 days at the same dosage.

Adolescent↗
PubMed1995

Role of a large plasmid in mediation of multiple drug resistance in Salmonella typhi and paratyphi A in Bangladesh.

From 405 patients of suspected typhoid fever, 94 Salmonella typhi and 17 Salmonella paratyphi A, were isolated from blood and/or stool at the Institute of Postgraduate Medicine and Research, Dhaka during March 1992 to February 1993. Forty seven percent of the isolates were resistant to multiple drugs which included amoxicillin, ampicillin, chloramphenicol and co-trimoxazole. A large plasmid of 140 MDa was isolated from 73% of multidrug resistant (MDR) strains. However, no plasmid was isolated from any of the strains sensitive to above mentioned antibiotics. Majority of MDR Salmonella transferred resistance to E. coli K-12 (Lac+, F-, NxR.) by conjugation method. The transconjugants were similarly resistant to multiple drugs. All Salmonella were sensitive to ciprofloxacin and ceftriaxone.

Drug Resistance↗
PubMed1994

Role of lateral preoptic area alpha-1 and alpha-2 adrenoceptors in sleep-wakefulness and body temperature regulation.

The preoptic area is anatomically divided into medial and lateral portions and both are involved in the regulation of sleep-wakefulness and body temperature. We have recently reported the specific role of the adrenoceptors, present in the medial preoptic area, in the regulation of those functions. In this study an attempt was made to investigate the specific participation and contribution of the lateral preoptic area alpha-1 and alpha-2 adrenoceptors in the regulation of sleep-wakefulness and body temperature. Sleep-wakefulness and rectal temperature were simultaneously recorded in freely moving rats, both during day and night, under normal condition and after bilateral local microinjection of either agonist or antagonist of alpha-1 and alpha-2 adrenoceptors into the lateral preoptic area. The results suggest that the lateral preoptic area alpha-2 adrenoceptors are predominantly involved in the regulation of sleep-wakefulness whereas alpha-1 adrenoceptors are more effective in thermoregulation.

Adrenergic alpha-1 Receptor Agonists↗
PubMed1992

Different types of norepinephrinergic receptors are involved in preoptic area mediated independent modulation of sleep-wakefulness and body temperature.

The preoptic area is known to regulate sleep-wakefulness and body temperature. It was suggested earlier that though sleep-wakefulness and body temperature may affect each other, the preoptic area mediated influence on those two physiological phenomena is likely to be independent of alteration in each other. Since intrapreoptic area norepinephrine could modulate both those functions, study of that system was undertaken. It was hypothesized that since the preoptic area has different types of norepinephrinergic receptors (viz. alpha 1, alpha 2 and beta), independent modulation of those two functions was probably due to activation or inactivation of separate receptors. Hence, the effects of different agonist and antagonist of those receptors individually as well as in combination into the preoptic area were studied on those two functions in freely moving rats. The results suggest that norepinephrine induced preoptic area mediated influence on the body temperature is primarily regulated by the alpha 1 receptors while the sleep and wakefulness are regulated by alpha 2 and beta receptors, respectively. The finding should help in explaining several poorly understood observations reported earlier and it suggests that similar phenomena may possibly exist in other system involving other neurotransmitters as well.

Acetamides↗
PubMed1991

Differential influence of medial and lateral preoptic areas on body temperature in conscious and unconscious rats.

Since temperature sensitive neurons are unevenly distributed in the medial and the lateral preoptic areas, it was hypothesized that the two areas possibly would influence body temperature to a different extent. As alteration in sleep-wakefulness and body movement may affect the body temperature, experiments were conducted by reversible inactivation of those two areas, in freely moving (conscious) rats as well as in rats where changes in EEG and movement were restricted (unconscious). Results showed that the medial preoptic area is more effective in body temperature regulation. The study also revealed that the preoptic area mediated effect on body temperature regulation is not necessarily linked to simultaneous changes in sleep-wakefulness and alteration in the latter probably helps in maintaining the former within limit.

Anesthesia, General↗
PubMed1991

Medial preoptic area affects sleep-wakefulness independent of associated body temperature change in free moving rats.

Sleep-wakefulness and body temperature may modulate each other. Though both the functions are influenced by the medial preoptic area, the mechanism of action was not clear. This study was aimed at finding out whether the tonic influence of the medial preoptic area on sleep-wakefulness was independent of or secondary to simultaneous change in body temperature. The effects of inactivation of the area by a long acting local anaesthetic, marcain, on those physiological functions were investigated during the night and the day in freely moving rats. Though medial preoptic area influenced sleep-wakefulness and body temperature simultaneously, the effect on the latter was prolonged. The results suggest that the influence on sleep-wakefulness is unlikely to be associated with simultaneously changing body temperature. However, this study fails to differentiate whether the observed effects were due to inactivation of the cell body or the fibers passing through the area.

Animals↗
PubMed1990

Differential acute influence of medial and lateral preoptic areas on sleep-wakefulness in freely moving rats.

The role of preoptic area (POA) in sleep-wakefulness and related EEG changes is well established. Anatomically the area is divided into medial (mPOA) and lateral (IPOA) portions having different physiological functions. Knowledge regarding the differential role, if any, of those two areas in sleep and wakefulness was lacking in the literature. Therefore, an attempt was made in this study, to investigate the same systematically. Experiments were conducted during day and night in freely moving rats. Electrophysiological parameters defining sleep and wakefulness were recorded before and after reversible inactivation of those two areas separately by microinjection of a local anaesthetic, marcain. The responses were opposite in nature depending upon the time, day or night, when the anaesthetic was applied. During the day, anaesthetization induced wakefulness while during the night, sleep was precipitated. However, anaesthetization of both the areas though induced similar qualitative response, the degree of the responses differed significantly. The results suggest that the mPOA is more effective in maintaining tonic sleep while the IPOA is more potent in the maintenance of tonic wakefulness in the normal rats. The finding supports and fits well with the existing knowledge.

Animals↗