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Biomedical subjects

M Husain

Publications and source records attributed to M Husain.

At least 37 records · Page 2Linked to original sources
PubMed2003

Percutaneous vertebroplasty: an experience of 31 procedures.

A prospective study of 31 percutaneous vertebroplasty procedures (PVP) in 22 patients treated during January 2000 to December 2001 is presented. PVP was performed using polymethylmethacrylate (PMMA) to treat vertebral collapse due to osteoporosis and vertebral metastasis, to obtain analgesia and spinal stabilization. We analyze the efficacy and complications related to the procedure. PVP is a safe, effective and a daycare surgery. It can be performed under local anesthesia and has minimal and manageable complications.

Adult↗
PubMed2002

Cerebellar hemangioblastoma simulating arachnoid cyst on imaging and surgery.

A case of posterior fossa hemangioblastoma simulating arachnoid cyst on imaging and peroperatively is presented. In vivo proton MR spectroscopy showed evidence of large lactate and resonance at 2.37 ppm not observed earlier in the cystic lesions, including arachnoid cyst. The demonstration of this resonance may help in characterization of these lesions that may be confused with arachnoid cysts on imaging and during surgery.

Adult↗
PubMed2002

Neural response to emotional faces with and without awareness: event-related fMRI in a parietal patient with visual extinction and spatial neglect.

This study examined whether differential neural responses are evoked by emotional stimuli with and without conscious perception, in a patient with visual neglect and extinction. Stimuli were briefly shown in either right, left, or both fields during event-related fMRI. On bilateral trials, either a fearful or neutral left face appeared with a right house, and it could either be extinguished from awareness or perceived. Seen faces in left visual field (LVF) activated primary visual cortex in the damaged right-hemisphere and bilateral fusiform gyri. Extinguished left faces increased activity in striate and extrastriate cortex, compared with right houses only. Critically, fearful faces activated the left amygdala and extrastriate cortex both when seen and when extinguished; as well as bilateral orbitofrontal and intact right superior parietal areas. Comparison of perceived versus extinguished faces revealed no difference in amygdala for fearful faces. Conscious perception increased activity in fusiform, parietal and prefrontal areas of the left-hemisphere, irrespective of emotional expression; while a differential emotional response to fearful faces occurring specifically with awareness was found in bilateral parietal, temporal, and frontal areas. These results demonstrate that amygdala and orbitofrontal cortex can be activated by emotional stimuli even without awareness after parietal damage; and that substantial unconscious residual processing can occur within spared brain areas well beyond visual cortex, despite neglect and extinction.

Aged↗
PubMed2002

Epilepsy and the law: an Indian perspective.

All over the world epileptic patients have traditionally been discriminated legally in matters affecting their everyday existence. India is no exception. In the current paper certain important issues are explored, namely, epilepsy in relation to marriage, criminality, driving and socio-economic crimes.

Journal Article↗
PubMed2001

Vision: Visual space is not what it appears to be.

The location of visual objects in the world around us is reconstructed in a complex way from the image falling on the retina. Recent studies have begun to reveal the different ways in which the brain dynamically re-maps retinal information across eye movements to compute object locations for perception and directing actions.

Animals↗
PubMed2001

Molecular characterization of HIV type 1 vpu genes from mothers and infants after perinatal transmission.

We compared 162 vpu sequences of human immunodeficiency virus type 1 (HIV-1) in peripheral blood mononuclear cell DNA of 6 infected mother-infant pairs after perinatal transmission, and found a 90.12% frequency of intact vpu open reading frames. The heterogeneity of vpu genes between epidemiologically linked mother-infant pairs was lower compared with epidemiologically unlinked individuals. However, the variability of vpu genes was higher than that seen for other HIV-1 genes, including vif, vpr, tat, and gag p17 from the same mother-infant pairs. Moreover, the infants' sequences displayed patterns similar to those seen in their mothers. The functional domains essential for Vpu activity, including efficient release of virus particles from infected cells and CD4 degradation, were conserved in most of the sequences. In a phylogenetic analysis, the 162 sequences from 6 mother-infant pairs formed distinct clusters for each mother-infant pair sequences and grouped with subtype B sequences. These data support the importance of vpu in HIV-1 replication of mother-infant isolates that are involved in perinatal transmission.

Adult↗
PubMed2001

Conditional and targeted overexpression of vascular chymase causes hypertension in transgenic mice.

We cloned a rat vascular chymase (RVCH) from smooth muscle cells (SMCs) that converts angiotensin I to II and is up-regulated in SMC from spontaneously hypertensive vs. normotensive rats. To determine whether increased activity of RVCH is sufficient to cause hypertension, transgenic mice were generated with targeted conditional expression of RVCH to SMC, with the use of the tetracycline-controlled transactivator (tTA). We confirmed conditional expression of RVCH by mRNA, protein, and chymase activity in the absence, but not in the presence, of dietary doxycycline. The systolic blood pressure (mmHg), measured by carotid artery cannulation at 10-12 weeks of age, was higher in tTA+/RVCH+ mice than in nonbinary transgenic littermates (136 +/- 4 vs. 109 +/- 3) (P < 0.05), as were the diastolic and mean pressures. Hypertension was completely reversed by doxycycline, suggesting a causal link with chymase expression. Medial thickening of mesenteric arteries from tTA+/RVCH+ mice vs. littermates (0.82 +/- 0.1 vs. 0.42 +/- 0.02) (P < 0.05) was associated with increased SMC proliferation, as judged by positive immunoreactivity, with the use of an antibody to the proliferating cell nuclear antigen. These structural changes were prevented by doxycycline. Perfusion myography of mesenteric arteries from tTA+/RVCH+ mice also revealed increased vasoconstriction in response to phenylephrine and impaired metacholine-induced vasodilatation when compared with littermate controls or with the doxycyline-treated group. Our studies suggest that up-regulation of this vascular chymase is sufficient to cause a hypertensive arteriopathy, and that RVCH may be a candidate gene and a therapeutic target in patients with high blood pressure.

Animals↗
PubMed2001

Characterization of HIV type 1 tat sequences associated with perinatal transmission.

Human immunodeficiency virus type 1 (HIV-1) tat exon I sequences were analyzed from six mother-infant pairs after perinatal transmission. The tat open reading frame was maintained in 140 of the 154 clones analyzed, with a 90.9% frequency of intact tat open reading frames. In addition, a low degree of heterogeneity was observed in tat sequences within mothers, within infants, and between epidemiologically linked mother-infant pairs. However, the distances of tat sequences between epidemiologically unlinked individuals were greater than in epidemiologically linked mother-infant pairs. The infant sequences showed amino acid sequence patterns similar to those present in their respective mothers. The functional domains required for Tat function, including amino-terminal, cysteine-rich, core and basic regions, which constitute domains for activation and RNA binding, were highly conserved in most of the sequences. Phylogenetic analysis of 154 mother-infant tat sequences showed that they formed distinct clusters for each mother-infant pair and grouped with subtype B sequence. These findings suggest that an intact and functional tat gene is conserved in HIV-1 mother-infant isolates that are involved in perinatal transmission.

Adult↗
PubMed2001

Identification of isochromosome 1q as a recurring chromosome aberration in skull base chordomas: a new marker for aggressive tumors?

OBJECT: The authors conducted a study of 22 skull base chordomas. METHODS: A series of 22 skull base chordomas was analyzed with G banding. Subsequently, metaphase cells obtained from three tumors were reexamined using multicolor spectral karyotyping. Clonal chromosome aberrations were identified in 11 cases, all of which were recurrent tumors. Three tumors showed a remarkable similarity in cytogenetic features, and these features appear to characterize a recurring combination of nonrandom chromosome aberrations, including isochromosome 1q, gain of chromosome 7, and monosomy for chromosomes 3, 4, 10,13, and 18. Isochromosome 1q was identified as the sole recurring structural chromosome rearrangement in these tumors. The pattern of chromosome loss reported in the progression of lumbosacral chordoma also appears to be true of skull base chordomas with the additional findings of isochromosome 1q, gain of chromosome 7, and loss of chromosome 18. CONCLUSIONS: Skull base chordomas characterized by isochromosome 1q and monosomy 13 provide support for the concept of the loss of putative tumor suppressor loci on 1p and 13q and aggressive tumor behavior.

Adolescent↗
PubMed2001

Spectroscopic increase in choline signal is a nonspecific marker for differentiation of infective/inflammatory from neoplastic lesions of the brain.

We report in vivo proton magnetic resonance (MR) spectroscopic findings in three benign infective/inflammatory lesions (one case each of tuberculoma, fungal granuloma, and xanthogranuloma), which showed high choline along with the presence of lipid/lactate, a feature characteristically described in neoplastic lesions. Histopathology of the lesions showed inflammatory cellular infiltrates with areas of necrosis/caseation. The spectroscopic-visible increased choline resonance in these lesions is probably the result of cellularity. We conclude that increased choline, along with the presence of lipid/lactate is a nonspecific finding and may not be of much value in the differentiation of neoplastic from nonneoplastic infective/inflammatory intracranial mass lesions.

Adolescent↗
PubMed2001

Role of sample adequacy in fine needle aspiration biopsy of palpable breast lesions.

BACKGROUND: The role of fine needle aspiration biopsy (FNAB) in breast lesions remains uncertain because its accuracy has been questioned. We hypothesized that this is related to failure to define standards for adequacy of sample preparation. METHODS: We reviewed cytology and pathology reports from 351 patients undergoing FNAB at a 350-bed community, university-affiliated teaching hospital over a 2-year period. Patients were included if they had an open biopsy within 2 years of an FNAB of the same lesion. Cytology reports were reviewed by a cytopathologist unaware of the clinical setting or subsequent histology; surgeons unaware of the cytology reports reviewed histology reports. Cytological diagnoses were benign, likely benign, probable cancer, and definite cancer. Samples were characterized as satisfactory, less than optimal (few mammary epithelial clusters), or inadequate (no mammary epithelial clusters.) We assessed the proportion of inadequate samples, the accuracy of FNAB, and the influence of sample adequacy upon FNAB sensitivity. RESULTS: Ninety-nine (28%) FNABs were inadequate, 77 (22%) less than optimal, and 175 (50%) satisfactory. Ninety-five patients (27%) had a final diagnosis of malignancy. FNABs classified as satisfactory or less than optimal and characterized as benign (n = 102) had a negative predictive value (NPV) of 0.91; those termed definite cancer (n = 43) had a positive predictive value (PPV) of 0.98. Only 10% of all cancers were identified in the 28% of FNABs that were classified as inadequate (P <0.01). CONCLUSIONS: We concluded that too few FNABs are performed in a fashion that permits definitive cytological interpretation. Inadequate FNABs are less likely to detect malignancy. After excluding inadequate preparations, FNABs interpreted as definite cancer and as benign are highly accurate in identifying patients with and without cancer.

Biopsy, Needle↗
PubMed2001

Spatial working memory deficit in unilateral neglect.

Based on the similarity of brain areas lesioned in neglect and those activated by spatial working memory (WM) tasks in normals, we hypothesized that neglect may involve spatial WM impairments. A left neglect patient with right inferior frontal and basal ganglia damage performed cancellation tasks, making either highly visible marks (to provide a reminder of visited items), or invisible marks (so only spatial WM could represent cancelled items). Invisible marks led to repeated cancellations for targets that differed only in location, but not for targets with memorable unique identities, suggesting a deficit of spatial WM, with non-spatial WM spared. Neglect was greater for cancellation with invisible marks, consistent with a role for deficient spatial WM in cancellation deficits, but contrary to account solely in terms of attention capture by salient visible marks made in ipsilesional space.

Attention↗
PubMed2001

Reaching with a tool extends visual-tactile interactions into far space: evidence from cross-modal extinction.

Several recent studies have shown cross-modal visual-tactile extinction in patients with right hemisphere lesions. In the present case, patient BV, a visual stimulus close to the right hand extinguished awareness of a touch on the left hand that would otherwise have been felt. Such extinction was reduced if the right visual stimulus was placed more distant from the patient's hand in the radial plane. However, when the patient held sticks in both hands, so that a far right visual stimulus was now at the end of the "tool" in his right hand, cross-modal extinction from this far stimulus increased. This effect depended on the patient holding a stick that reached to the position of the far visual stimulus; a similar large stick, but not connected with the patient's hand and laying passively on the right, had no effect. Wielding the stick induced a re-mapping of space, so that the far light became treated as near (and reachable by) the hand, thus modifying the spatial nature of cross-modal extinction. This may relate to the properties of multimodal neurons as found in the monkey intraparietal sulcus.

Aged↗
PubMed2001

Prospective evaluation of in vivo proton MR spectroscopy in differentiation of similar appearing intracranial cystic lesions.

Proton MR spectroscopy (PMRS) has been found to be useful in differentiating various cystic intracranial lesions. The purpose of the present study was to prospectively evaluate the spectral pattern of various cystic lesions of brain with similar imaging appearances and to determine the accuracy of this technique in the differential diagnosis of these lesions. Fifty-one patients with intracranial cystic lesions (21 abscesses, 20 gliomas, 3 hydatid cysts, 3 arachnoid cysts, 1 case each of glioependymal cyst, xanthogranuloma, infarction and acoustic neuroma) were evaluated with conventional MR imaging and in vivo PMRS. Ex vivo PMRS of the cystic contents aspirated at surgery in 31 cases was also done to confirm the in-vivo results. Preoperative diagnosis of the lesions was based on the results of in vivo PMRS. In vivo PMRS accurately predicted the pathology in 92% of the cases. We conclude that in-vivo PMRS complements imaging in better characterization of cystic intracranial mass lesions.

Adolescent↗
PubMed2001

Platelet inhibitory effect of nitric oxide in the human coronary circulation: impact of endothelial dysfunction.

OBJECTIVES: We sought to determine whether coronary vascular nitric oxide (NO) release in vivo modulates platelet activation. BACKGROUND: Nitric oxide modulates vasodilator tone and platelet activity via the cyclic guanosine monophosphate (cGMP) pathway, but whether coronary endothelial dysfunction influences platelet activation in humans is unknown. METHODS: In 26 patients, we measured coronary blood flow, epicardial diameter and coronary sinus platelet cGMP content during intracoronary infusions of acetylcholine (ACH), L-NG monomethyl arginine (L-NMMA) and sodium nitroprusside. RESULTS: Acetylcholine increased platelet cGMP content (p = 0.013), but its magnitude was lower in patients with endothelial dysfunction; thus, patients with epicardial constriction with ACH had a 7 +/- 6%, p = ns change compared with a 32 +/- 13%, p = 0.05 increase in platelet cGMP in those with epicardial dilation. Similarly, patients with atherosclerosis or its risk factors had a smaller increase (9 +/- 6%) compared with those having normal coronary arteries without risk factors (51 +/- 22%, p = 0.019). L-NG monomethyl arginine decreased platelet cGMP content to a greater extent in patients with epicardial dilation with ACH (- 15 +/- 7%, p = 0.06) compared to those with constriction (+5 +/- 6% change, p = 0.5). Sodium nitroprusside produced a similar increase in platelet cGMP content in patients with and without endothelial dysfunction (p = 0.56). The effects of sodium nitroprusside, but not ACH or L-NMMA, were reproduced in vitro. CONCLUSIONS: Platelet cGMP levels can be modulated by basal and stimulated release of NO. The platelet inhibitory effect of NO is reduced in patients with endothelial dysfunction, which may explain their increased risk from thrombotic events and the improved survival associated with strategies designed to improve vascular function.

Acetylcholine↗
PubMed2001

Platelet 3H ketanserin binding in migraine.

Platelet 3H ketanserin binding was studied in 33 patients of migraine and 30 healthy controls. The binding characteristics: equilibrium dissociation constant (Kd) and maximal number of binding sites (Bmax) determined by Scatchard analysis revealed a significant decrease in Kd and no change in Bmax in migraine cases. No correlation was observed between the Kd and Bmax with the clinical features of migraine. The findings of the present study show that there is a decreased affinity of platelet 5-HT2 receptors in migraine.

Adult↗