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Biomedical subjects

S Naeem

Publications and source records attributed to S Naeem.

14 recordsLinked to original sources
PubMed2002

Interaction of group I mGlu and NMDA receptor agonists within the dorsal horn of the spinal cord of the juvenile rat.

1. The modulatory effects of mGlu receptors on NMDA-induced potential changes in spinal motoneurones were studied in vitro. 2. Selective activation of mGlu5 receptors by 10 microM (RS)-2-Chloro-5-hydroxyphenylglycine (CHPG; EC(50)=280 +/- 24 microM) did not produce any change in the ventral root potential. However, the same concentration of CHPG (10 min perfusion) significantly attenuated the NMDA-induced ventral root depolarization (VRD). The effect persisted for 10 min after washout. NMDA-induced responses returned to control in 30 min. Brief co-application of CHPG and NMDA did not alter the NMDA-induced response indicating lack of direct receptor interaction. 3. The attenuating effect of CHPG on the NMDA-induced VRD was inhibited by the mGluR5 receptor antagonist, 2-methyl-6-phenyl-ethynylpyridine (MPEP). 4. In the presence of CGP56433A, a GABA(B) receptor antagonist, the NMDA-induced VRD was unchanged. However, NMDA-induced responses were potentiated after 10 min co-application of CHPG and CGP56433A. 5. (2R,4R)-4-aminopyrrolidine-2,4-dicarboxylate ((2R,4R)-APDC), a group II mGlu receptor agonist did not attenuate the NMDA-induced response. 6. Under normal physiological conditions group I mGlu receptor agonists activate at least two populations of neurones: (1) GABA-ergic cells, which could release GABA and inhibit dorsal horn neurones, and (2) deep dorsal horn neurones/motoneurones which express NMDA receptors. Therefore, activation of mGlu5 receptors located on GABA-ergic interneurones could influence any direct potentiating interaction between mGlu5 and NMDA receptors in spinal cord and result in depression of the VRD. In the presence of a GABA(B) receptor antagonist, the direct synergistic interaction is unmasked. These data suggest that group I mGlu receptors provide a complex modulation of spinal synaptic processes.

Animals↗
PubMed2001

Biodiversity and ecosystem functioning: current knowledge and future challenges.

The ecological consequences of biodiversity loss have aroused considerable interest and controversy during the past decade. Major advances have been made in describing the relationship between species diversity and ecosystem processes, in identifying functionally important species, and in revealing underlying mechanisms. There is, however, uncertainty as to how results obtained in recent experiments scale up to landscape and regional levels and generalize across ecosystem types and processes. Larger numbers of species are probably needed to reduce temporal variability in ecosystem processes in changing environments. A major future challenge is to determine how biodiversity dynamics, ecosystem processes, and abiotic factors interact.

Animals↗
PubMed2001

Plant diversity enhances ecosystem responses to elevated CO2 and nitrogen deposition.

Human actions are causing declines in plant biodiversity, increases in atmospheric CO2 concentrations and increases in nitrogen deposition; however, the interactive effects of these factors on ecosystem processes are unknown. Reduced biodiversity has raised numerous concerns, including the possibility that ecosystem functioning may be affected negatively, which might be particularly important in the face of other global changes. Here we present results of a grassland field experiment in Minnesota, USA, that tests the hypothesis that plant diversity and composition influence the enhancement of biomass and carbon acquisition in ecosystems subjected to elevated atmospheric CO2 concentrations and nitrogen deposition. The study experimentally controlled plant diversity (1, 4, 9 or 16 species), soil nitrogen (unamended versus deposition of 4 g of nitrogen per m2 per yr) and atmospheric CO2 concentrations using free-air CO2 enrichment (ambient, 368 micromol mol-1, versus elevated, 560 micromol mol-1). We found that the enhanced biomass accumulation in response to elevated levels of CO2 or nitrogen, or their combination, is less in species-poor than in species-rich assemblages.

Atmosphere↗
PubMed2001

A case notes analysis of hysterectomy performed for non-neoplastic indications at Liaquat National Hospital, Karachi.

OBJECTIVE: To determine the indications, associated morbidity, mortality and histopathological findings in women who underwent hysterectomy for non-neoplastic indications at Liaquat National Hospital Karachi. MATERIAL AND METHODS: This is a five year retrospective case note study of 143 women who underwent hysterectomy, excluding all those performed for benign or malignant pelvic neoplasms (excluding fibroids) and hysterectomy following childbirth for postpartum haemorrhage. RESULTS: Menorrhagia was the commonest indication for performing hysterectomy. The majority of the patients were in their forties; the commonest post operative complications were pyrexia, urinary tract and wound infections in 16% of the patients. There was no mortality associated with the procedure. The histopathology of the specimens revealed adenomyosis followed by leiomyoma to be the commonest pathology. CONCLUSION: It appears that adenomyosis is a common pathology in women from various ethnic and social backgrounds in Karachi, who are suffering from menorrhagia. Early diagnosis with high-resolution ultrasound is possible and hysterectomy may be offered earlier to these women, as they do not usually respond to medical treatment.

Adult↗
PubMed2000

Producer-decomposer co-dependency influences biodiversity effects.

Producers, such as plants and algae, acquire nutrients from inorganic sources that are supplied primarily by decomposers whereas decomposers, mostly fungi and bacteria, acquire carbon from organic sources that are supplied primarily by producers. This producer-decomposer co-dependency is important in governing ecosystem processes, which implies that the impacts of declining biodiversity on ecosystem functioning should be strongly influenced by this process. Here we show, by simultaneously manipulating producer (green algal) and decomposer (heterotrophic bacterial) diversity in freshwater microcosms, that algal biomass production varies considerably among microcosms (0.0-0.67 mg ml(-1)), but that neither algal nor bacterial diversity by itself can explain this variation. Instead, production is a joint function of both algal and bacterial diversity. Furthermore, the range in algal production in microscosms in which bacterial diversity was manipulated was nearly double (1.82 times) that of microcosms in which bacterial diversity was not manipulated. Measures of organic carbon use by bacteria in these microcosms indicate that carbon usage is the mechanism responsible for these results. Because both producer and microbial diversity respond to disturbance and habitat modification, the main causes of biodiversity loss, these results suggest that ecosystem response to changing biodiversity is likely to be more complex than other studies have shown.

Bacterial Physiological Phenomena↗
PubMed1996

B1 bradykinin receptors and sensory neurones.

1. The location of the B1 bradykinin receptors involved in inflammatory hyperalgesia was investigated. 2. No specific binding of the B1 bradykinin receptor ligand [3H]-des-Arg10-kallidin was detected in primary cultures of rat dorsal root ganglion neurones, even after treatment with interleukin-1 beta (100 iu ml-1). 3. In dorsal root ganglion neurones, activation of B2 bradykinin receptors stimulated polyphosphoinositidase C. In contrast, B1 bradykinin receptor agonists (des-Arg9-bradykinin up to 10 microM and des-Arg10-kallidin up to 1 microM) failed to activate polyphosphoinositidase C, even in neurones that had been treated with interleukin-1 beta (100 iu ml-1), prostaglandin E2 (1 microM) or prostaglandin I2 (1 microM). 4. Dorsal root ganglion neurones removed from rats (both neonatal and 14 days old) that had been pretreated with inflammatory mediators (Freund's complete adjuvant, or carrageenan) failed to respond to B1 bradykinin receptor selective agonists (des-Arg9-bradykinin up to 10 microM and des-Arg10-kallidin up to 1 microM). 5. Bradykinin (25 nM to 300 nM) evoked ventral root responses when applied to peripheral receptive fields or central terminals of primary afferents in the neonatal rat spinal cord and tail preparation. In contrast, des-Arg9-bradykinin (50 nM to 500 nM) failed to evoke ventral root depolarizations in either control rats or in animals that developed inflammation following ultraviolet irradiation of the tail skin. 6. The results of the present study imply that the B1 bradykinin receptors that contribute to hypersensitivity in models of persistent inflammatory hyperalgesia are located on cells other than sensory neurones where they may be responsible for releasing mediators that sensitize or activate the nociceptors.

Animals↗
PubMed1996

Receptors mediating tachykinin-evoked depolarisations of neurons in the neonatal rat spinal cord.

We have examined the contribution of NK1, NK2 and NK3 receptors to the depolarisation of the neonatal rat spinal cord in vitro evoked by exogenously applied tachykinine. Potential changes were recorded extracellularly from a lumbar ventral root. The NK1 receptor selective agonists substance P methly ester (SPOMs), septide and/Sar9/-substance P-sulphone (/Sar9/-P-sulphone), perfused onto the cord for 20 s, evoked ventral root potentials (VRPs) with similar EC50 values of 7.2 nM (95% confidence limits, 4.4-10.9 nM), 4.6 nM (1.8-9.3 nM) and 3.1 nM (1.6-5.1 nM), respectively. The NK3 receptor selective agonist senktide also evoked VRPs with an EC50 of 12.0 nM (5.1-23.4 nM), whilst the NK2 receptor selective agonist/beta-AlaB/-neurokinin A(4-10) (/beta-AlaB/-NKA(4-10)) was much less potent (EC50 = 228.3 nM, 95% confidence limits 138.0-350.0 nM). The non-peptide NK1 receptor selective antagonist RP67580 inhibited responses to SPOMe, septide and/Sar9/-SP-sulphone to varying degrees with IC50 values against each of 16.0 nM (10.7-23.4 nM), 19.8 nM (8.9-37 nM) and 58.0 nM (41-89 nM), respectively. The NK1 receptor antagonist CP-96,345 similarly inhibited responses to these agonists, although with higher IC50 estimates of 0.84 microM (0.51-1.40 microM) against SPOMe, 0.79 microM (0.50-1.17 microM) against/Sar9/-SP-sulphone and 0.37 microM (0.27-0.51 microM) against septide. Further analysis of the activity of RP67580 yielded a significantly higher pKB estimate for antagonism of responses to septide (7.67 +/- 0.04) than of responses to/Sar9/-SP-sulphone (7.18 +/- 0.05). In both cases Schild analysis indicated competitive antagonism. RP67580 also reversibly inhibited responses to /beta-AlaB/-NKA(4-10). However, in this case the Schild alope was significantly different from unity (0.44 +/- 0.55; P < 0.001), although the potency of the antagonist appeared similar to that seen with the NK1 receptor agonists (pA2 = 7.52). There was no effect of RP67580 against responses to senktide or of the inactive isomer RP67581 against septide-evoked VRPs. The NK2 receptor antagonist MEN 10,376 at concentrations up to 1 microM produced a partial but reversible inhibition of responses to a submaximal concentration of /beta-AlaB/-NKA(4-10) (0.3 microM) with a maximum reduction in VRP amplitude of 25.6 +/- 7.3%. A similar inhibitory effect was seen against septide-evoked VRPs (30.2 +/- 5.6% inhibition), although there was no effect against responses to submaximal concentrations of /Sar9/-SP-sulphone or senktide. In contrast, the non-peptide NK2 receptor antagonist SR 48,968 (1 microM) produced a maximal 48.0 +/- 7.7% inhibition of/beta-AlaB/-NKA(4-10)-evoked VRP's with no effect against responses to a submaximal concentration of septide. These data show that NK1 and NK3 receptor activation mediates depolarisation of the neonatal rat spinal cord, and suggest the presence of two NK1 receptor populations showing preference for septide and/Sar9/-SP-sulphone. Depolarisations mediated by /beta-AlaB/-NKA(4-10), previously described as a selective NK2 receptor ligand, are mediated predominantly via an action at NK1 receptors with a lesser involvement of NK2 receptors.

Animals↗
PubMed1994

Tachykinin induced regulation of excitatory amino acid responses in the rat spinal cord in vitro.

The interaction between neurokinin and excitatory amino acid receptors in the spinal cord have been characterised using the neonatal rat spinal cord in vitro preparation. Ventral root (VR) depolarization evoked by N-methyl-D-aspartate (NMDA) and quisqualate was reversibly enhanced in the presence of subthreshold concentrations of neurokinin A (NKA; 1.0-10 nM), but not by substance P (1.0-5.0 nM). When substance P (SP) was replaced by the metabolically stable substance P methyl ester (SPOMe), both NMDA and quisqualate responses were significantly enhanced. VR depolarization evoked by kainate was not altered by any of the neurokinin (NK) receptor agonists. In the presence of the endopeptidase inhibitors, bestatin, captopril and thiorphan (each 1.0 microM), SP significantly enhanced NMDA-evoked responses. The selective NK1 receptor antagonist (+/-) CP96 345 (100 nM) reversibly blocked the enhancement of NMDA-evoked depolarization by SPOMe. Furthermore, MEN10 376 (50 nM), a selective NK2 receptor antagonist blocked the enhancement of NMDA- and quisqualate-evoked depolarization by NKA. The protein kinase C and protein kinase A inhibitor staurosporine (1.0 microM) blocked the enhancement of excitatory amino acid-induced responses by NK-receptor activation. However, whilst NKA-evoked ventral root depolarization was completely abolished in the presence of staurosporine, SPOMe- and SP-induced depolarizations were unaffected. These data show that activation of NK1 or NK2 receptors enhances NMDA- and quisqualate-evoked ventral root depolarization in the neonatal rat spinal cord. The interaction between neurokinin and excitatory amino acid receptors involves protein kinase C activation.

Alkaloids↗
PubMed1992

Vulnerability factors for depression in Pakistani women.

The vulnerability factors were tested in a retrospective study on 50 cases and 50 controls. Only one of the four factors, i.e., lack of an intimate, confiding relationship, was found to be statistically significant, thus highlighting the need for indigenous research particularly in areas where the variables are socio-culturally determined.

Adolescent↗
PubMed1992

Acute lymphoblastic leukaemia--a study of immunophenotypes.

Immunological characteristics of leukaemic blast cells from 55 patients of acute lymphoblastic leukaemia were analysed using a panel of monoclonal antibodies and immunoperoxidase technique. Among 36 children the percentage of Common-ALL was found to be low (39%) as compared to western reports, whereas that of T-ALL was high (36%). Out of 19 adults, 52.6% were Common-ALL, 21.1% Early-B-ALL and 16% T-ALL; the findings being consistent with western studies. The T-ALL cases (13) were subclassified according to the stage of thymic maturation depending upon the expression of CD8 and CD4 antigens. Six were identified as early, 3 as common and 4 as late thymocyte stage.

Adult↗
PubMed1991

Alexithymia in Karachi.

Alexithymia is a new term which usually means "no words for mood" and used to describe a disorder where patients have difficulty in expressing feelings in words. Such patients therefore express emotions in somatic terms. We have selected headache as a symptom to test the term Alexithymia. A group of thirty patients with the complaint of persistent headache of more than 6 months duration, without any organic pathology or neurological disease entity was taken. This study concludes that Alexithymic traits are not necessarily more prominent in those having psychophysiological symptoms specially tension headache. It also shows that we should not accept any new concept evolved in West without testing it in our own conditions.

Adolescent↗
PubMed1984

First rank symptoms and diagnosis of schizophrenia in developing countries.

Schneider's first rank symptoms (FRS) among schizophrenics in Karachi are compared with samples from Saudi Arabia and the UK. Although the incidence of one or more FRS were very close to Saudi Arabia, the individual FRS were different, and somatic passivity was similar to the UK. It is concluded that cultural factors are more important than religious affinity in determining symptomatology. The results could be due to selection of schizophrenic patients on Western parameters. The place of FRS in developing countries and the changing concept of schizophrenia is discussed.

Adolescent↗