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Biomedical subjects

N Hussain

Publications and source records attributed to N Hussain.

At least 37 records · Page 2Linked to original sources
PubMed2001

Intraspinal neurenteric cysts--report of three paediatric cases.

BACKGROUND: Neurenteric cysts are rare congenital lesions of the spine and are lined with entodermal epithelium. They result from anomalous endodermal-neuroectodermal adhesion in the 3rd week of embryonic life with persistence of canal of Kovalevsky. The nature of the eventual abnormality depends on the extent to which this adhesion subsequently disappears. Persistence of the entire tract results in the extreme form of combined anterior and posterior spina bifida with dorsal enteric fistula and persistence of only a part of the tract producing the isolated intraspinal cyst. The most common location is the cervico-dorsal region, and usually it lies ventral to the spinal cord. The lumbosacral location is uncommon. Associated vertebral anomalies, gut cysts, bowel duplication, the presence of keratin markers and mucin-secreting cuboidal or columnar intestinal epithelium in their walls confirm their entodermal origin. PATIENTS: We describe here three unusual cases of neurenteric cysts in patients aged 5-18 years who had already had symptoms for some time. One of these had a cyst sited predominantly in the sacral canal, another presented with a lumbar neurenteric cyst, and the third patient had an intradural extramedullary thoracic lesion. Two of these children had associated anomalies, the one with lumbar cyst also having a lipomeningomyelocele and spina bifida while the other also had deformed vertebrae. All three patients underwent laminectomy and gross excision of the cysts through a posterior approach. RESULTS AND CONCLUSION: The diagnosis of neurenteric cysts was confirmed by demonstrating mucin-producing cuboidal or columnar epithelium lining the cystic cavity.

Adolescent↗
PubMed2001

Glutamatergic regulation of haloperidol-induced c-fos expression in the rat striatum and nucleus accumbens.

Acute administration of haloperidol induces the expression of the immediate-early gene c-fos in the striatum and nucleus accumbens via dopamine D(2) receptor antagonism. Dopaminergic transmission in the striatum and nucleus accumbens is modulated by glutamate via N-methyl-D-aspartate (NMDA) receptors. Indeed, haloperidol-induced c-fos expression is dependent on NMDA receptor activation in the dorsolateral part of the striatum. However, the role that NMDA receptors play in haloperidol-induced c-fos expression in other functionally distinct areas of the striatum and nucleus accumbens has not yet been established. Therefore, in the present study the entire rostrocaudal extent of the rat striatum and nucleus accumbens was examined to determine the role that NMDA receptors play in haloperidol-induced c-fos expression. Pretreatment with MK-801, a non-competitive antagonist of NMDA receptors, significantly reduced the number of neurons showing c-fos immunoreactivity in the rostral aspect of the dorsolateral striatum and the entire rostrocaudal extent of the ventrolateral striatum following an acute injection of haloperidol. However, the same treatment did not modify the pattern of haloperidol-mediated c-fos expression in the medial or central parts of the striatum. Similarly, MK-801 pretreatment significantly suppressed the number of neurons expressing c-fos immunoreactivity following haloperidol injection in the entire rostrocaudal extent of the shell region of nucleus accumbens, but not in the core region. The results indicate that haloperidol-induced c-fos expression is dependent on NMDA receptors only in the rostral aspect of the dorsolateral striatum and the rostrocaudal extent of the ventrolateral striatum, the areas involved in motor function. The differential role that NMDA receptors play in modulating haloperidol-mediated dopamine D(2) receptor antagonism between motor and associative areas of the striatum may contribute to the development of extrapyramidal symptoms following chronic haloperidol treatment. Furthermore, the attenuation of the haloperidol-induced c-fos expression by MK-801 was restricted to the nucleus accumbens shell, an area often implicated in the therapeutic effect of haloperidol. Therefore, the NMDA-dopamine D(2) receptor interaction may also play a role in mediating the therapeutic effects of haloperidol.

Animals↗
PubMed2001

Role of Bi-pap in acute respiratory failure due to acute exacerbation of COPD.

OBJECTIVE: To assess the efficacy of Bi-level Positive Airway Pressure (Bi-pap), administered by nasal mask in patients with acute respiratory failure due to acute exacerbation of COPD. DESIGN: Prospective non-randomized study in a hospital setting. METHODS: Eighteen patients were recruited from those admitted in the Chest Unit of Jinnah Postgraduate Medical Centre, Karachi with acute exacerbation of COPD. Along with conventional treatment, Bi-pap was administered by a nasal mask. Arterial blood gas analysis, respiratory and heart rate and subjective sensation of dyspnoea, before and during Bi-pap application were monitored. RESULTS: The respiratory rate decreased from 33.2 +/- 5.3/min to 22.0 +/- 3.5 (P < 0.001), heart rate also decreased from 113.2 +/- 7.6/min to 90.2 +/- 11.9 (P < 0.001). A rise in pH was observed from 7.2 +/- 0.09 to 7.4 +/- 0.06 (P > 0.41 n.s.), PaCO2 decreased from 76.5 +/- 15.5 to 51.3 +/- 10.5 (P < 0.001). PaO2 also increased from 52.1 +/- 14.3 to 62.9 +/- 11.5 (P < 0.01). The mean hospital stay was shorter i.e., 10.6 +/- 5.6 days and the hospital mortality rate 11.1%. Bi-pap administered by nasal mask was generally well tolerated with few minor complications. CONCLUSION: Bi-pap is particularly useful in patients presenting with acute respiratory failure due to acute exacerbation of COPD particularly in our setting where invasive ventilation is not easily available.

Aged↗
PubMed2001

Carotid artery disease and ocular vascular disorders.

The carotid artery supplies blood to the structures of the eye; therefore a variety of ocular vascular disturbances can occur secondary to abnormalities in the parent vessels. The ocular manifestations of chronic carotid artery abnormalities may often be subtle and overlooked or they may be acute, where the contribution of the carotid arteries in the aetiology may not be apparent on routine clinical evaluation. Ophthalmologists and neurologists working independently may not recognise the effects of carotid artery disturbances on the eye and missed diagnoses are not infrequent. In our experience of almost a decade in a tertiarycare referral hospital, we have not recorded any patient referred to us from a primary referring physician (either ophthlamologist or neurologist) as a case of ocular manifestation of a carotid artery disease. This brief review highlights the important clinical features, diagnostic modalities and therapeutic options in this group of disorders.

Carotid Artery Diseases↗
PubMed2000

Cationic lipid-based delivery system for systemic cancer gene therapy.

A cationic lipid-based gene delivery system composed of N-[(1-(2,3-dioleyloxy)propyl)]-N-N-N-trimethylammonium chloride and cholesterol, at a 4:1 molar ratio, was developed for systemic administration. Plasmid biodistribution and expression were characterized in syngeneic mouse tumor model squamous cell carcinoma VII cells. A reporter gene expression plasmid was used for biodistribution of plasmid and expression. The results showed that lungs and primary tumors were transfected. Fluorescence microscopy showed that fluorescent-labeled transfection complexes were passively targeted to the tumor vasculature and that the endothelial cells internalized the plasmid. Transgene expression was characterized based on duration of expression and dosing schedule. In vivo gene transfer with an interleukin-12 expression plasmid yielded protein levels in blood, lungs, and primary tumor after intravenous administration. Efficacy studies showed that 15 microg of interleukin-12 plasmid was sufficient to produce a gene-specific inhibition of primary tumor growth. These results characterize the vascularity of the tumor model, characterize the in vivo gene transfer properties of the plasmid-based gene delivery system, and show that the transgene expression level was sufficient to elicit a biological response by inhibiting tumor growth.

Animals↗
PubMed2000

Allergic gastroenteropathy in preterm infants.

OBJECTIVES: To determine the clinical presentation, histopathologic features, and outcome of biopsy-proven allergic gastroenteropathy (AGE) in preterm infants. We hypothesized that AGE is a more frequent cause of gastrointestinal disease in this population than previously suspected. STUDY DESIGN: The retrospective portion of the study, from 1992 to 1997, included preterm infants <37 weeks' gestation who underwent biopsy because of suspected AGE. The prospective portion, from January to December 1998, included 20 infants undergoing endoscopy and biopsy because of suspected AGE. RESULTS: Twenty-five infants (12 retrospective/13 prospective) with mean gestational age of 29 weeks at birth and mean postnatal age at diagnosis of 78 days were diagnosed with AGE. Three clinical patterns of presentation were noted: group 1, gastroesophageal reflux disease (n = 5); group 2, non-specific feeding intolerance (n = 8); and group 3, lower gastrointestinal bleeding (n = 12). Ten patients had negative biopsy findings (3 retrospective/7 prospective) and had clinical features indistinguishable from those of groups 1 and 2. Patients in group 3 were most likely to have positive biopsy findings (12 of 12). Fifteen patients responded to a casein hydrolysate formula, and 10 patients required an amino acid-based formula. Patients with AGE who had eosinophilic infiltration and villous atrophy took longer to recover than those with eosinophilic infiltration alone (P <.03). Subsequently, most have tolerated formula challenges and are currently tolerating cow's milk. CONCLUSIONS: AGE may be an under-recognized cause of gastrointestinal symptoms in preterm infants. Confirmation with endoscopy and biopsy can be done safely and provides the basis for appropriate dietary management.

Follow-Up Studies↗
PubMed2000

Floquet exponents of underdamped josephson ladders: A comparison with predictions of the discrete sine-gordon equation

We calculate Floquet exponents for phase-locked solutions in ladder arrays of Josephson junctions in zero external field. We assume a resistively and capacitively shunted junction (RCSJ) model, and we allow for critical current anisotropy between the horizontal and vertical junctions. The ladders range in size from 5 to 30 plaquettes and are biased along the rungs with uniform dc bias currents. The Floquet exponents quantify the stability of the solutions and are calculated numerically for the RCSJ model as a function of junction capacitance (beta(c)) as well as critical current anisotropy (Lambda). We also model the array with the discrete sine-Gordon (DSG) equation, and we are able to calculate the exponents analytically in that case. We find the analytic results from the DSG equation agree quantitatively with the numerical results from the RCSJ model over a wide range of beta(c) and Lambda values and even agree qualitatively for beta(c)-->1 and Lambda-->0. Based on the analytic result we argue that perturbations in the array are damped by the small-angle phase oscillations of the underlying lattice (the "phonons" of the lattice), and like a classical harmonic oscillator with damping, each phonon mode has a crossover (as a function of decreasing beta(c) or Lambda) from underdamped to overdamped dynamics. Such crossover behavior is clearly visible in the results for the Floquet exponents and is manifested as a maximum in the Floquet exponent as a function of the junction capacitance. This intriguing result speaks to the opportunity, in principle, of tuning the capacitance such as to optimize the stability of the phase-locked solutions.

Journal Article↗
PubMed2000

Construction of adenovirus for high level expression of small RNAs in mammalian cells. Application to a Bcl-2 ribozyme.

A series of plasmid vectors have been generated to allow the rapid construction of adenoviral vectors designed to express small RNA sequences. A truncated human U6 gene containing convenient restriction sites has been shown to be expressed at high levels following electroporation into a series of human cell lines. This gene was ligated into a promoterless adenoviral plasmid, and we have generated high titer virus by homologous recombination with adenoviral Addl327 DNA in 293 cells. Recombinant adenovirus containing a hammerhead ribozyme sequence targeted toward the Bcl-2 mRNA has been used to transduce a panel of human tumor cell lines. We have demonstrated high level expression of the recombinant U6 gene containing the ribozyme and reduction of Bcl-2 protein in transduced cells. These plasmids are suitable for the development of adenoviral vectors designed to express both ribozymes and antisense RNA in human cells.

Adenoviridae↗
PubMed2000

Diagnosis and management of spinal epidural space extravasation complicating percutaneous central venous line placement in a premature infant: case report and review of literature.

Percutaneous central venous lines are commonly used to establish long-term venous access in the care of premature infants. Misplacement of these catheters can occur and may lead to significant morbidity and mortality. Here we report a very-low-birth-weight premature infant whose percutaneous central venous line was inadvertently placed into the spinal epidural space. The anatomical basis of this complication as well as a comprehensive review of literature are provided.

Catheterization, Central Venous↗
PubMed2000

A study of the influence of insulin resistance on left ventricular mass in hypertensive patients.

OBJECTIVES: To study the influence of insulin resistance on the left ventricular mass in hypertensive subjects. MATERIAL AND METHODS: Thirty patients having uncomplicated essential hypertension were included in the study. Post-oral glucose load serum insulin level (2 hrs) was determined and this was used as a marker for insulin resistance. Two D-echocardiography was performed and left ventricular mass and left ventricular mass index were calculated. RESULT: Out of the 30 patients 18 were males and 12 were females. Eight were obese while the remaining 22 were non-obese. The patients were 27 to 70 years old. The mean age, height and weight were 54.83 +/- 9.46 years, 159.07 +/- 8.81 cm and 58.38 +/- 11.03 kg, respectively. The post oral glucose load serum insulin levels in the study ranged from 57.65 to 210.81 microU/ml. The left ventricular mass and left ventricular mass index ranged from 42.58 to 310.8 g (mean 196.60 +/- 65.13 g) and 42.74 to 185.59 g/m2 (mean 118.71 +/- 37.75 g/m2), respectively. The correlation coefficient ('r' value) between post oral glucose load serum insulin levels and left ventricular mass and left ventricular mass index were calculated. CONCLUSION: A strong positive correlation was observed between the post oral glucose load serum insulin levels and left ventricular mass ('r' = +0.750). A strong positive correlation between post oral glucose load serum insulin levels and left ventricular mass index ('r' = +0.757) was also observed. These correlations were found to be statistically highly significant (p < 0.01). This association was demonstrated independently of age, anthropometric measurements, systolic and diastolic blood pressure levels. Thus, in patients with essential hypertension, hyperinsulinemia (insulin resistance) has a role in promoting left ventricular hypertrophy.

Adult↗
PubMed1999

Bombesin inhibits apoptosis in developing fetal rat lung.

We have shown recently that apoptosis occurs during fetal and postnatal lung development. Our hypothesis that branching morphogenesis occurs through a delicate balance of cell proliferation and apoptosis predicts that substances that enhance branching of the airways would affect both cell proliferation and apoptosis in the lung. Bombesin-like peptides have a mitogenic effect on bronchial epithelium and fibroblasts, and bombesin has been shown to enhance branching morphogenesis in fetal lung. We used organ cultures of 16-day gestation fetal rat lung to study the effects of bombesin on apoptosis. Cultures were incubated in serumless medium alone or exposed to 1microM bombesin for 0-48 h. Levels of apoptosis were quantified using the TUNEL assay and expressed as percentage of apoptotic cells in paraffin sections of explants. Bombesin significantly inhibited apoptosis in fetal lung mesenchyme 48 h in culture by more than 50% (p < 0.05). The effects of bombesin on apoptosis were prevented completely if explants were exposed to the specific bombesin receptor antagonist, [D-Phe12]bombesin. To examine if the absence of serum in the media could have accounted for some of these effects, explants were cultured for 48 h in serumless medium, medium containing 10% fetal bovine serum, serumless medium with 1 microM bombesin, or medium containing both 10% fetal bovine serum and 1 microM bombesin. The addition of fetal bovine serum to the media reduced apoptosis significantly. The effect of fetal bovine serum on apoptosis was additive with bombesin. We conclude that bombesin inhibits apoptosis in developing fetal rat lung mesenchyme through its interaction with the bombesin receptor.

Animals↗
PubMed1999

Pulmonary hemorrhage in neonates of early and late gestation.

Our objectives in this study of pulmonary hemorrhage (PH) were to define common characteristics of infants who develop PH, identify factors associated with PH and report the outcome. Neonates (42/2980 admissions) with PH and matched controls were identified. Early gestation (< or = 35 weeks) infants with PH [EGPH] (n = 34; 12 survived) had occurrence of PH at 3.6 +/- 1.1 (mean +/- sem) days and were significantly associated with multiple births (p = 0.03), RDS (p < 0.01) and use of Survanta (p < 0.02). Among EGPH, small for gestational age (SGA) infants (n = 7) had a 100% mortality rate. Late gestation (> or = 36 weeks) infants with PH [LGPH] (n = 8; 6 survived) had occurrence of PH at 0.7 +/- 0.3 days and were significantly associated with low 1 minute (p = 0.04) and 5 minutes (p = 0.01) Apgar scores. All infants were managed with increases in mean airway pressure (MAP) and/or use of cocaine/epinephrine through the endotracheal tube. We have identified 2 groups of neonates with distinct factors associated with PH; use of 1:10,000 epinephrine (0.1 ml/kg) and/or 4% cocaine (4 mg/kg) may be useful adjuncts to increases in MAP for management of PH.

Biological Products↗
PubMed1999

Current incidence of retinopathy of prematurity, 1989-1997.

OBJECTIVE: To report the current incidence and the need for surgery for retinopathy of prematurity (ROP) in neonates (22-36 weeks' gestational age [GA], July 1, 1989 through June 30, 1997). STUDY DESIGN: Retrospective analyses using computerized perinatal database kept on all admissions, a review of patient charts, and eye examination log books. SETTING: Level 3 regional referral NICU. PATIENTS: A total of 2528 infants <37 weeks' GA were admitted during this time. Of these infants, 950 met the criteria for eye examination beginning at 4 to 6 weeks of age and repeated every 2 weeks until complete vascularization of the retina or death or discharge. RESULTS: The incidence of ROP was (202/950) 21.3% for any stage and 4.6% (44/950) for stage 3 ROP or greater. No ROP was noted in infants born at >32 weeks' GA. No infant born at >28 weeks needed retinal surgery. Using birth weight (BW) criteria, stage 3 ROP was not noted in infants with BWs >1500 g; retinal surgery was not needed in infants with BWs >1000 g. A number of perinatal factors were associated with ROP on univariate analysis. However, using multiple logistic regression analyses of these factors, only GA and days on supplemental oxygen therapy were associated significantly with the development of ROP. Despite increased survival of extremely low BW infants, we found a considerable reduction in incidence and severity of ROP compared with reports from an earlier chronological period. However, infants <28 weeks' GA or with BWs <1000 g were still at considerable risk for retinal surgical treatment for ROP. CONCLUSION: We conclude that the incidence and severity of ROP have decreased significantly in the present era of surfactant therapy.

Analysis of Variance↗