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Biomedical subjects

M Hossain

Publications and source records attributed to M Hossain.

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

Improvement in pulsed wave Doppler echocardiographic assessment of pulmonary artery pressure.

Non invasive estimation of pulmonary artery pressure (PAP) is of paramount importance in various form of cardiac, respiratory and intensive care medicine practice. Using pressure gradient between different chambers enables a reliable estimation of PAP and are being largely practiced. In absence of these pressure gradient, various time interval or the ratios of pulmonary blood flow velocity curve (PBFVC) in pulsed wave doppler echocardiography (PWDE) can predict the PAP. But there is lack of general agreement as which parameter should be used. We hypothesized that using separate time interval or their ratios of PBFVC for different group of patient may improve the PWDE prediction of PAP. Forty-six consecutive patients with different cardiac diseases and 20 consecutive control persons underwent PWD echocardiographic examination. Pulmonary blood flow velocity curve derived time intervals--the time intervals--time to peak velocity (TPV), Pre-ejection period (PEP) and right ventricular ejection time (RVET) and their ratios were measured. The Doppler derived measurements were compared with cardiac catheterization (CC) measured PAP in 46 patients in whom CC were done. PBFVC derived time interval TPV and the ratio PEP/TPV correlated well with CC measured systolic PAP (r=-0.78 and r=0.77 respectively). For congenital left to right shunt disease the ratio PEP/TPV improved the prediction (r=-0.87) while the same measure showed weak correlation in patients with left sided heart disease. Only TPV could predict mean PAP in patients with left sided heart disease (r=-0.60). We concluded that the use of separate PBFVC derived time interval or their ratio from PWDE may improve the prediction of PAP with different pathological group of disease.

Blood Pressure Determination↗
PubMed2002

Delayed presentation of post-traumatic aneurysm of the posterior inferior cerebellar artery in a patient with spinal cord injury.

STUDY DESIGN: A case report. OBJECTIVE: To present and discuss the case of a patient with serious head and spinal injuries who suffered delayed haemorrhage from a post-traumatic aneurysm of the right posterior inferior cerebellar artery following surgical treatment of vertebral fracture and hydrocephalus. SETTING: National Spinal Injuries Unit and Institute of Neurological Sciences, Southern General Hospital, Glasgow, Scotland, UK. METHODS: Clinical and radiological follow-up of the patient. RESULTS: The aneurysm was treated by coil occlusion of the right vertebral artery. Post-operative films showed that the aneurysm had been successfully obliterated. CONCLUSION: Post-traumatic cerebral aneurysms are very rare. Neurosurgical and rehabilitation teams need to be aware of this late treatable sequela of head injury.

Adolescent↗
PubMed2002

Oxcarbazepine final market image tablet formulation bioequivalence study after single administration and at steady state in healthy subjects.

A final market image (FMI) tablet formulation of oxcarbazepine was compared with the marketed formulation (current market formulation (CMF)) and with the clinical trial formulation (CTF) tablet used during clinical efficacy and safety studies. The goal of the study was to compare the bioavailability after single doses and at steady state of the FMI versus CMF and CTF as well. Additionally, the effect of food was evaluated on the final market formulation. The study was an open-label, single-center, 4-way crossover trial. Each treatment period consisted of a single dose of 600 mg OXC on Day 1. From Day 4 up to including Day 7, 600 mg b.i.d. were administered. A final dose of 600 mg was administered in the morning on Day 8. Blood samples were taken on Day 1 before and on Day 7 (predose) and on Day 8 (morning dose). Plasma concentrations of MHD (the main metabolite of OXC) were determined by using a validated HPLC assay. FMI as test formulation was compared with the CMF and CTF as reference formulations. FMI under fed conditions was also compared with FMI under fasting conditions. These comparisons were made using data following single-dose administration and steady state conditions. Plasma AUC for single dose or AUC(0-12h) for steady state, and plasma Cmax, log-transformed (natural base), were used for the assessment of bioequivalence. The 90% confidence interval (CI) approach was used for testing bioequivalence. Bioequivalence was accepted if the CI was contained within the region (0.8, 1.25). At steady state under fed conditions, tested formulation (FMI) was bioequivalent to CTF and with the reference marketed formulation (CMF) with regard to AUC and Cmax. After single dose under fed conditions, FMI and CTF were bioequivalent with regard to AUC and Cmax, and FMI and CMF were equivalent with regard to AUC but not Cmax. Food had no effect on the bioavailability of the FMI. These results clearly support the switch from the current market formulation (CMF) to the final market image tablet in the countries where Trileptal is or was already registered.

Administration, Oral↗
PubMed2002

Microleakage of composite resin restoration in cavities prepared by Er:YAG laser irradiation in primary teeth.

AIM: The purposes of this study were to investigate the surface morphology of cavities prepared by Er:YAG laser irradiation and to compare the microleakage degree after composite resin restoration with etched bur cavities in primary teeth, in vitro. MATERIALS AND METHODS: On the buccal (facial) and lingual (palatal) surfaces of 25 primary teeth, a round cavity was prepared with the Er:YAG laser system and with a high-speed diamond bur, respectively. Five cavities from each group were investigated by scanning electron microscopy (SEM). The remaining cavities were filled with a composite resin and subjected to a microleakage test (0.6% rodamine B solution) under thermocycling. Only bur cavities were acid-etched before filling. Statistical analysis was performed using the Mann-Whitney's U test; a value of p < 0.01 was considered significant. RESULTS: SEM observation of the laser and etched bur cavities revealed an absence of a smear layer; enamel rods and opening of dentinal tubules were recognized. No statistically significant differences were noted between microleakage of composite resin restorations of the laser and the etched bur cavities. Crosscut sections of the cavities with no microleakage showed good adhesion between the restorative material and dental hard tissues; there was also no gap at the interface. DISCUSSION: The highly irregular surface or the removal of the debris-like smear layer after laser irradiation may facilitate good adhesion of composite resin with enamel or dentine, and these surfaces might play a major role in decreasing microleakage of laser cavities. CONCLUSION: It can be concluded that cavities prepared by Er:YAG laser are capable of decreasing microleakage of composite resin restorations in primary teeth, and the efficiency is similar to etched bur cavities.

Journal Article↗
PubMed2001

Facile allylic C-H bond activation on the bridging disulfide ligand in the Ru(III) dinuclear complex having a conjugated RuSSRu core.

Treatment of [[Ru(P(OCH(3))(3))(2)(CH(3)CN)(3)](2)(mu-S(2))](CF(3)SO(3))(4) (1), which is prepared by the reaction of [[RuCl(P(OCH(3))(3))(2)](2)(mu-S(2))(mu-Cl)(2)] (2) with 4 equiv of AgCF(3)SO(3), with terminal alkenes such as 1-pentene, allyl ethyl ether, allyl phenyl ether, 1,4-hexadiene, and 3-methyl-1-butene, resulted in the formation of complexes carrying a C(3)S(2) five-membered ring, [[Ru(P(OCH(3))(3))(2)(CH(3)CN)(3)](2)[mu-SCH(2)CH(2)CR(1)R(2)S]](CF(3)SO(3))(4) (3, R(1) = CH(2)CH(3), R(2) = H, 40%; 4, R(1) = OCH(2)CH(3), R(2) = H, 60%; 5, R(1) = OC(6)H(5), R(2) = H, 73%; 6, R(1) = CH=CHCH(3), R(2) = H, 48%; 7, R(1) = R(2) = CH(3), 40%). Reaction of 1 with methylenecycloalkanes was found to give several different types of products, depending on the ring size of the substrates. A trace of [[Ru(P(OCH(3))(3))(2)(CH(3)CN)(3)](2)[mu-SCH(CH(2)CH(2))CH(CH(3))S]](CF(3)SO(3))(4) (9) having a C(2)S(2) four-membered ring to bridge the two Ru atoms was obtained by the reaction of 1 with methylenecyclobutane, whereas the reaction with methylenecyclohexane gave [[Ru(P(OCH(3))(3))(2)(CH(3)CN)(3)](2)[mu-S(CH(2)(C=CHCH(2)CH(2)CH(2)CH(2))S)](CF(3)SO(3))(3) (10) in 69% yield via C-S bond formation and elimination of a proton. Throughout these reactions with alkenes giving a variety of products, the activation of the allylic C-H bond is always the essential and initial key step.

Journal Article↗
PubMed2001

An investigation of a model of percentage depth dose for irregularly shaped fields.

A significant component of the total dose delivered to tumor and surrounding tissue during a radiation treatment arises from the scattering of the primary beam. Accounting for this component accurately and efficiently is a necessity. In this study we investigate a method for calculating the phantom-scatter contributions to the total dose by simple summation of scatter dose from a set of individual triangles that span an irregular field. The calculation of phantom scatter is based on a two-parameter model, which is applicable to regions where electron equilibrium is established. The two physical parameters are the dose-averaged linear attenuation coefficient and the beam-hardening coefficient. The advantage of this model is that it is a natural method when an irregular field is shaped by a multi-leaf collimator (MLC). Accuracy is not compromised by the triangulation since the irregular field is defined by the straight edges of the MLC leaves. The model predicts the percent depth dose with acceptable accuracy for any arbitrary shape of fields. We report on results for 6- and 18-MV photon beams and for a number of irregularly shaped fields.

Electrons↗
PubMed2001

Magnetic behavior of na films with Fe, Co, and Ni impurities.

Thin films of Na with Fe, Co, and Ni impurities are investigated. The magnetization of the impurities is measured by means of the anomalous Hall resistance. Fe and Co show a moment of about 6mu(B), while for Ni no moment is detected. Furthermore, the magnetic dephasing of the conduction electrons is measured by means of weak localization. The dephasing rate 1/tau(phi) of the 3d impurities differ qualitatively. For Fe impurities, 1/tau(phi) is so large that it cannot be measured. For Co, 1/tau(phi) has a moderate value while Ni shows hardly a dephasing effect at all.

Journal Article↗
PubMed2001

Effect of early fetal irradiation on the postnatal development of mouse.

BACKGROUND: An earlier study has shown that irradiation at the late fetal stage of Swiss albino mice disturbed postnatal growth and appearance of physiological markers. The present study was done to determine the effect of irradiation at the early fetal stage on the postnatal development of mouse. METHODS: Fourteen-day pregnant Swiss albino mice were exposed to 0.1-1.5 Gy of cobalt-60 gamma-rays. F1 pups were observed for < or = 6 weeks of age. Postnatal mortality, body weight and length, head length and width, tail length, and the time of appearance of physiological markers (pinna detachment, eye opening, fur development, vaginal opening and testes descent) were noted. RESULTS: There was no increase in congenital anomalies. Postnatal mortality and percentage of growth-retarded pups increased significantly at doses of 0.5-1.5 Gy. A significant delay in the appearance of all the physiological markers was also noted at these doses. Body length, head length, and tail length remained significantly lower than in the controls throughout the observation period at doses of 0.3-1.5 Gy, whereas body weight and head width showed such a persistent change only at > or = 0.5 Gy. CONCLUSIONS: The early fetal day 14 in mouse is sensitive to radiation-induced postnatal mortality and impairment of growth and temporal development of physiological markers, but not to induction of congenital anomalies. While mortality and physiological markers are not affected at <0.5 Gy, growth retardation appears to have a lower threshold of approximately 0.3 Gy.

Abnormalities, Radiation-Induced↗
PubMed2001

Intra-individual postural blood pressure variability and stroke in elderly nursing home residents.

Orthostatic hypotension (OH) is a potential risk factor for adverse cardiovascular events, but OH is highly variable and may not be detected on a single occasion. To assess the relation between intra-individual variability of systolic orthostatic blood pressure change (DeltaSBP) and cardiovascular outcomes, an algorithm was developed to identify DeltaSBP instability using repeated supine and standing BP measurements. A cohort of 673 nursing home residents underwent baseline postural BP measurements (supine to 1 minute of standing, four times in a single day) and were followed for up to 2 years. Two groups (stable vs. unstable) were identified based on an analysis of DeltaSBP variance components. Differences in outcomes were compared via Cox survival analysis. At baseline 12.6% were unstable, defined as a one standard deviation difference of at least 20.2 mmHg between DeltaSBP readings. Unstable subjects were more likely to have OH on at least one measurement (systolic BP drop of 20 mmHg or more; 85% vs. 36%, respectively) and to be on psychotropic medication at baseline (47% vs 35%) (P-values <0.001). Other characteristics (including previous stroke) did not differ. During a mean follow-up of 10.3 months, stroke incidence was higher in unstable subjects (13.1% vs. 4.9%; P = 0.012), but ischemic heart disease and mortality rates were not significantly different (respectively, 13.5% vs. 7.4%, P = 0.115; 14.8% vs. 10.7%, P = 0.178). Survival analyses (adjusted for age, sex, psychotropic medications, body mass index, ischemic heart disease, and supine systolic pressure) confirmed a higher risk of stroke in unstable subjects (relative risk = 3.7, 95% CI: 1.6-8.4). Highly variable orthostatic BP measures may reflect impaired BP regulatory mechanisms in elders with occult cerebrovascular disease, or may directly affect cerebral blood flow. Orthostatic BP variability may be a better indicator of future stroke than a single supine or orthostatic change measure.

Aged↗
PubMed2001

Radiation-induced acute intestinal inflammation differs following total-body versus abdominopelvic irradiation in the ferret.

PURPOSE: The studies were designed to investigate the differences in the intestinal inflammatory response following abdominopelvic or total-body irradiation in a ferret model. MATERIALS AND METHODS: Ferrets were exposed either to total-body or to abdominopelvic gamma-radiation (5 Gy) and various parameters of inflammation studied in the jejunum, ileum and colon 2 and 7 days later. RESULTS: Abdominopelvic and, to a greater extent, total-body irradiation caused weight loss by 7 days. White blood cell counts were reduced in both groups, but more so following total-body irradiation. Myeloperoxidase activity was significantly increased in the ileum 2 days after abdominopelvic irradiation, but it was reduced after total-body irradiation. Total-body irradiation increased tissue prostaglandin E2 levels in all regions at 2 days and decreased jejunal leukotriene B4 levels in the jejunum at both time points. Ileal prostaglandin E2 levels were increased 2 days after abdominopelvic irradiation. Expression of inducible nitric oxide synthase was not altered by either irradiation protocol. CONCLUSIONS: The data show that there are regional differences in the intestinal response to irradiation, depending on whether it was delivered to the whole body or locally to the abdominopelvic region. In particular, the ileum exhibited an acute increase in myeloperoxidase activity following abdominopelvic but not total-body irradiation.

Animals↗
PubMed2001

Effect of irradiation at the early foetal stage on adult brain function of mouse: learning and memory.

PURPOSE: To study the long-term effect of early foetal irradiation on the learning and memory in the adult mouse. MATERIALS AND METHODS: The abdominal area of pregnant Swiss albino mice was exposed to a single dose of 0.25-1.5Gy gamma-radiation on the 14th day of gestation and the mice were left to deliver their offspring. At 6 months of age, the learning and memory functions of the F(1) mice were tested by hole-board activity, conditioned avoidance response and radial arm maze performance. The animals were again subjected to the radial arm maze test at 12 and 18 months of age. RESULTS: There was a significant dose-dependent decrease in the learning ability and memory retention of 6-month-old mice at doses > 0.25Gy. The significant changes persisted to 18 months of age in mice exposed to >or= 0.5Gy. All changes showed a linear dose-response at doses < 1Gy. CONCLUSIONS: The gestational day 14 of Swiss albino mice is a sensitive stage in brain development to gamma-ray-induced impairment of learning and memory during the adult life. Permanent deficits in these functions can be induced by a dose of approximately 0.5Gy at this stage, when the developmental activity of the cerebral cortex is at its peak.

Age Factors↗
PubMed2001

Treatment of lymphangioma with Nd:YAG laser irradiation: a case report.

OBJECTIVE: In this case report, the treatment of a buccal lymphangioma in a 9-year-old female was done using the Nd:YAG laser and the clinical outcome was evaluated. BACKGROUND DATA: The treatment of lymphangioma with the laser surgery using Nd:YAG and CO2 laser has become favorable due of a lack of postoperative pain and hemorrhage. METHODS: The lesion was treated with a pulsed Nd:YAG laser (d-lase 300, American Dental Laser, Detroit, MI). An exposure of 10 min each was performed at an interval of 10 days by the noncontact method with the energy density of 1 W, 10 Hz. RESULTS: It was observed that there was a great reduction of the lesion and a considerable reduction of the external facial volume. As the excision of the lesion was avoided in our present study, there was no pain and hemorrhage. A remarkable reduction of the tumor size could be observed visually within the five laser exposures. CONCLUSIONS: It can be concluded that if Nd:YAG laser therapy is used for reducing the tumor size as a primary treatment, the operation becomes easy and the recurrence may be less than with the conventional treatment, and an option of a surgical or laser excision could be reserved.

Child↗
PubMed2001

Comparison between the removal effect of mechanical, Nd:YAG, and Er:YAG laser systems in carious dentin.

OBJECTIVE: The purpose of this study was to compare the effectiveness of carious dentin removal by using an Er:YAG laser irradiation and Nd:YAG laser under a continuous water spray with that of the conventional mechanical treatment in vitro. BACKGROUND DATA: Lasers are being considered as a potential replacement of conventional mechanical systems to remove diseased and healthy dental hard tissues. METHODS: First, one half of the 10 carious lesions were treated with the round steel bur and then removed. The other half were treated with the Er:YAG laser at 200-mJ pulse energy at 2 Hz. After that, one half of another set of 10 teeth was subjected to the round steel bur in which the other half was removed using the Nd:YAG laser at 6-W output power, 20 pps, and under a continuous water spray (120 mL/min). Thermal change during each treatment and the time required for carious dentin removal was determined, and the surface characteristic was observed using the scanning electron microscopic (SEM). RESULTS: The Er:YAG or Nd:YAG laser irradiation time was almost two or three times longer than the bur treatment, respectively. From the SEM study, it was found that the lased cavity surface revealed various patterns of microirregularity, and there was also no smear layer. CONCLUSIONS: It can be suggested that under adequate water spray and with a careful irradiation technique, cavities without sign of thermal damage to the surrounding tissues as well as dental pulp could be produced with the Er:YAG and Nd:YAG laser.

Dental Caries↗
PubMed2001

Removal of carious dentin by Er:YAG laser irradiation with and without carisolv.

OBJECTIVE: The purpose of this study was to investigate the effectiveness of caries removal by using an Er:YAG laser irradiation with and without Carisolv, in vitro. BACKGROUND DATA: Effective ablation of dental hard tissues using Er:YAG laser has been reported and its application to caries removal has been expected. METHODS: Five extracted human teeth were selected for Carisolv and burr treatment. One-half of the lesion was treated with the Carisolv and then removed. The other half was removed using burr treatment. Fifty teeth were subjected to Er:YAG laser treatment with and without Carisolv. First, Carisolv was applied on one-half of each carious lesions for 1 min and followed by the Er:YAG laser irradiation at 60-140 mJ, 2 Hz for another 1 min; the other half was treated with Er:YAG laser only. The cavity was carefully assessed by DIAGNOdent. Each lesion was photographed before and after treatment, and the treated cavity was observed by microscopy and with scanning electron microscope (SEM). RESULTS: Our results revealed that application of Carisolv followed by Er:YAG laser irradiation at 100-140 mJ pulse energy effectively removed dentin caries. From the SEM study, it was found that the cavity surface treated with the laser revealed various patterns of microirregularity, often accompanied by microfissure propagation. There was also no smear layer. CONCLUSIONS: It was revealed that Er:YAG laser and Carisolv could provide an alternative technique for caries removal for conventional mechanical drilling and cutting.

Dental Caries↗
PubMed2001

Study on acid resistance of human dental enamel and dentin irradiated by semiconductor laser with Ag(NH3)2F solution.

OBJECTIVE: The purpose of this study was to investigate the acquired acid resistance of human dental enamel and dentin treated by 38% diamine silver fluoride [Ag(NH3)2F] solution and semiconductor (diode) laser irradiation in vitro. BACKGROUND DATA: There have been no reports on the acid-resistant effect by combined use of fluoride and semiconductor laser. METHODS: Sixty crowns of extracted human molars were divided into two groups for enamel and dentin samples, and each group was subdivided into three subgroups of 10 each. Each subgroup of enamel and dentin samples served as a control; one was treated with Ag(NH3)2F and the other was treated with Ag(NH3)2F and semiconductor laser irradiation at 2 W for 30 sec. Then all samples were immersed in 5 ml of 0.1 M lactic acid (pH 4.8) at 37 degrees C for 24 h. The concentration of calcium ion (Ca2+) dissolved in the solution was measured by atomic absorption spectrophotometry, and the samples were observed by stereoscopy and scanning electron microscopy (SEM). RESULTS: In both enamel and dentin samples, dissolved Ca2+ concentration in Ag(NH3)2F- or Ag(NH3)2F- and laser-treated group was significantly decreased compared with that in the control (p < 0.01). SEM findings showed that numerous cubic particles ranging from 0.1 to 0.5 mcirom were observed only in the combined treated groups of both enamel and dentin samples. CONCLUSIONS: A significantly decreased solubility of human enamel and dentin was acquired after treatment by Ag(NH3)2F and semiconductor laser irradiation, which suggested that this combined use has the capability of a more efficient acid-resistant effect on human dental hard tissues.

Cariostatic Agents↗
PubMed2001

A study on acquired acid resistance of enamel and dentin irradiated by Er,Cr:YSGG laser.

OBJECTIVE: This investigation was performed to evaluate the acid resistance of lased enamel and dentin by Er,Cr:YSGG laser to artificial caries-like lesions by spectrophotometry, and the ultrastructure of lased areas was investigated by scanning electron microscopy (SEM) in vitro. BACKGROUND DATA: In recent years, many studies have been performed to evaluate the effects of Er,Cr:YSGG laser on dental hard tissues. However, there have been only a few studies to determine if this laser is suitable for caries preventive treatments. METHODS: An Er,Cr:YSGG laser was used to irradiate the enamel or dentin samples from 30 extracted human molars at 6 W (67.9 J/cm2) or 5 W (56.6 J/cm2) pulse energy, respectively, with or without water mist. Samples were subjected to 2 microl of 0.1 M lactic acid solution (pH 4.8) for 24 h at 36 degrees C. The parts per million (ppm) of calcium ion (Ca2+) dissolved in each solution was determined by atomic absorption spectrophotometery, and the morphological changes were investigated by SEM. RESULTS: The lowest mean Ca2+ ppm was recorded in the lased samples. SEM observation showed that the lased areas were melted and seemed to be thermally degenerated. After acid demineralization, the thermally degenerated enamel or dentin surfaces were almost unchanged. CONCLUSIONS: The results of this study suggested that Er,Cr:YSGG laser irradiation with and without water mist appears to be effective for increasing acid resistance.

Dental Enamel↗