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Biomedical subjects

N Saeed

Publications and source records attributed to N Saeed.

At least 19 recordsLinked to original sources
PubMed2005

Schizophrenia syndromes associated with changes in ventricle-to-brain ratios: a serial high-resolution three-dimensional magnetic resonance imaging study in first-episode schizophrenia patients using subvoxel registration and semiautomated quantification.

A cohort of patients with first-episode schizophrenia was dichotomised into two age- and sex-matched groups of clinical syndromes, the active and withdrawn, and underwent high-resolution three-dimensional magnetic resonance imaging at baseline and 8 months later. A cohort of age- and sex-matched normal controls was also imaged at the same time intervals. The application of subvoxel registration and semiautomated quantification techniques demonstrated a significantly different outcome in ventricular changes between the two groups of patients. Compared with the controls, the withdrawn patients showed progressive ventricular enlargement, with an increase in ventricle-to-brain volume ratio, whereas the active group showed a reduction in ventricle-to-brain volume ratio, with a change opposite in sign and smaller in magnitude. These findings lend further support for the aetiological validity of this syndromal model of schizophrenia and are likely to be of importance in furthering our understanding of its pathogenesis and in the development of suitable therapeutic strategies.

Adult↗
PubMed2003

Rapid reversal of hepatic steatosis, and reduction of muscle triglyceride, by rosiglitazone: MRI/S studies in Zucker fatty rats.

AIM: This study aimed to chart the time course and durability of the effects of rosiglitazone, a potent thiazolidinedione-based peroxisome proliferator-activated receptor gamma agonist, on hepatic steatosis and intramyocellular lipid in an animal model of obesity, the Zucker Fatty (ZF) rat. METHODS AND RESULTS: Rosiglitazone (3 mg/kg/day p.o.) significantly reduced both liver fat content (by 59%; p < 0.05) and size (11.5%; p < 0.05) in male ZF rats that received between 3 days and 1 week of treatment, and these reductions were maintained for at least 12 weeks. Liver fat content measured by magnetic resonance spectroscopy (MRS) correlated closely and positively with plasma insulin levels (reduced by 89% within a week, r = 0.8) and with postmortem histological fat fractional volume (r = 0.89). Similarly, liver volume measured by magnetic resonance imaging (MRI) correlated closely with postmortem wet weight (r = 0.99). MRS also showed, and numbers of lipid vacuoles counted in transmission electron micrographs confirmed, that rosiglitazone significantly reduced the elevated intramyocellular lipid seen in ZF rat skeletal muscle by at least 40% (p < 0.05). CONCLUSIONS: Localized MRS and MRI showed that rosiglitazone reversed the hepatic steatosis, hepatomegaly and intramyocellular lipid, characteristic of the ZF rat, an animal model of obesity.

Animals↗
PubMed2002

Reconstruction of the temporomandibular joint autogenous compared with alloplastic.

The aims of and indications for temporomandibular joint (TMJ) reconstruction are well-established but the method of reconstruction is controversial. We describe a retrospective, two-centre audit of 49 patients treated with costochondral grafting and 50 patients treated with alloplastic joints. The characteristics of the patients were similar in both centres and the minimum follow-up period was 2 years. For each patient a number of variables were recorded including both subjective scores (pain and interference with eating) and objective data (interincisal distance). Patients in both groups showed an improvement in symptoms but more patients required reoperation in the autogenous group.

Adolescent↗
PubMed2002

Cerebellum segmentation employing texture properties and knowledge based image processing: applied to normal adult controls and patients.

A semi-automated method is described for segmenting the cerebellum from T(1)-weighted 3-dimensional magnetic resonance imaging scans of adult controls and patients. The method relies on prior knowledge involving a user-defined template as a guide to aid the segmentation of the cerebellum. As the gray and white matter intensity distribution in the cerebellum has a complex pattern, texture information that identified the "graininess" was employed to capture the intensity distribution of voxels. The textural information was used to group voxels in a small circular structuring element as belonging to the cerebellum region. The cerebella from scans of 15 of the 20 subjects were segmented both manually and using the semi-automated procedure; the results were strongly correlated (r = 0.985, n = 15, p < 0.0001), and the volumes obtained from the two methods differed by 2.3%. The cerebellar volumes in 10 normal subjects and 10 age- and sex-matched patients with a neuropsychiatric disorder (schizophrenia) did not differ significantly (p = 0.18). The whole cerebellum was segmented in approximately 30 min using the semi-automated procedure. The method described is robust, easy-to-use, fairly fast and gives objective measurements.

Cerebellum↗
PubMed2002

Bispectral index-guided management of anaesthesia in permanent vegetative state.

A patient in a permanent vegetative state required general anaesthesia for dental surgery. Because of the uncertainties involved in the appropriate monitoring and assessment of the conscious level of patients in a permanent vegetative state, it was decided to use the bispectral index to help guide the anaesthetic depth during surgery. We found that the bispectral index profile during anaesthesia and surgery was similar to that of a normal subject. The findings raise the possibility that patients in permanent vegetative states might sense noxious stimuli at a cortical level.

Anesthesia, Dental↗
PubMed2002

Subvoxel image registration of multislice (2D) magnetic resonance images in patients with high-grade gliomas of the brain.

AIMS: To implement a multislice two-dimensional (2D) T2-weighted sequence suitable for subvoxel image registration and to assess its usefulness in detecting change in high-grade intracranial gliomas. MATERIALS AND METHODS: Twenty patients with high-grade gliomas were studied on two or more occasions. T2-weighted multislice pulse sequences with a Gaussian slice profile, 50% overlapping slices and nearly isotropic voxels were acquired. The images were registered and subtraction images were produced. The images were compared with three-dimensional (3D) T1-weighted registered images and conventional unregistered T2-weighted images. All images were scored for changes in the lesions and ventricular system. RESULTS: The 2D and 3D registered subtraction images were the most sensitive for detecting changes in both the lesions and other regions in the brain. The mean rank scores were significantly higher for the lesions (chi2=86.742; df=5, n=38, P<0.0001) and for the ventricles (chi2=63.837; df=5, n=35, P<0.0001) compared with the unregistered and registered anatomical images. The subtraction images were also most sensitive for detecting signal intensity changes irrespective of the direction of change. CONCLUSION: Rigid body subvoxel registration can be successfully performed with both multislice 2D and 3D imaging. In principle, virtually all forms of clinical MR images of the brain can be accurately registered and subtracted.

Adult↗
PubMed2002

Magnetic resonance imaging in preeclampsia and eclampsia complicated by visual disturbance and other neurological abnormalities.

This study describes magnetic resonance imaging findings in women presenting with neurological complications associated with preeclampsia and eclampsia. One eclamptic and two preeclamptic women were studied after presenting with postpartum neurological events. In two women the brain increased in size on the initial follow-up images, following the same pattern seen in normal pregnancy. In the other woman, the brain was decreased in size at 13 days postpartum but increased in size at six weeks postpartum. This initial reduction in brain size may reflect the resolution of cerebral oedema resulting from underlying pathological processes.

Journal Article↗
PubMed2001

A serial longitudinal quantitative MRI study of cerebral changes in first-episode schizophrenia using image segmentation and subvoxel registration.

Lateral ventricular enlargement is the most consistently replicated brain abnormality found in schizophrenia. This article reports a first episode, longitudinal study of ventricular volume using high-resolution serial magnetic resonance imaging (MRI) and recently developed techniques for image registration and quantitation. Baseline and follow-up (on average 8 months later) MRI scans were carried out on 24 patients and 12 controls. Accurate subvoxel registration was performed and subtraction images were produced to reveal areas of regional brain change. Whereas there were no differences between patients and controls with respect to the mean change in ventricular volume, the patients were much more variable in this respect and showed larger increases and decreases. The percentage increase in ventricular size was greater than one standard deviation of control values for 14 patients and the percentage decrease exceeded one standard deviation in eight patients. Although the finding of progressive ventricular enlargement in a proportion of patients supports other studies indicating an ongoing neuropathological process in the early stages of schizophrenia, the reduction of ventricular size in the remaining patients is more difficult to explain. It is suggested that this may reflect improvement in nutrition and hydration following treatment.

Adult↗
PubMed2001

Visceral adipose tissue and metabolic complications of obesity are reduced in Prader-Willi syndrome female adults: evidence for novel influences on body fat distribution.

Visceral obesity is detrimental to health, but the mechanisms controlling body fat distribution are not fully understood. In premenopausal adult females (30 nonobese, 14 obese [body mass index >30 kg/m(2)]), variance in fasting insulin, glucose, insulin/glucose ratio, C-peptide/insulin ratio, triglycerides, and high-density lipoprotein/low-density lipoprotein-cholesterol ratio, were independently influenced by visceral but not total sc or abdominal sc adipose tissue, as measured by whole-body magnetic resonance imaging. Adult females with Prader-Willi syndrome (n = 13) had significantly reduced visceral adiposity, compared with obese controls (visceral/total sc adipose tissue ratio: 0.067 +/- 0.017 vs. 0.108 +/- 0.021), independent of their total adiposity (P < 0.001), or use of exogenous sex steroids. This is in contrast to that expected by their physical inactivity, hypogonadism, adult GH deficiency, and psychiatric problems. Females with Prader-Willi syndrome not receiving sex steroids (n = 8) had significantly reduced fasting insulin, insulin/glucose ratio, and triglycerides and increased C-peptide/insulin ratio, compared with obese controls, adjusting for total (P < 0.05) but not visceral adiposity (P = 0.3-0.6), supporting their association. The cause of the reduced visceral adiposity in Prader-Willi syndrome may reflect novel hormonal, hypothalamic, and/or genetic influences on body fat distribution.

Adipose Tissue↗
PubMed2000

Reduced development of cerebral cortex in extremely preterm infants.

Most growth in cortical connections and complexity occurs after 25 weeks. The cerebral cortex of extremely preterm infants when imaged at gestational age 38-42 weeks had less cortical surface area and was less complex than in normal infants born around term (p<0.0148 and p<0.0002, respectively), despite similar term-corrected cerebral tissue volumes. Since deficits acquired during critical periods of brain development may be permanent, these results suggest a neural substrate for the neurocognitive impairment that is frequent among such preterm infants.

Cerebral Cortex↗
PubMed2000

Preferential loss of visceral fat following aerobic exercise, measured by magnetic resonance imaging.

The aim of this study was to use whole-body magnetic resonance imaging (MRI) together with biochemical and anthropometric measurements to study the influence of regular moderate exercise with no dietary intervention on adipose tissue distribution in nonobese healthy women. We found significant decreases in both total (28.86+/-2.24 vs. 27.00+/-2.27 liters, P < 0.05) and regional fat depots (visceral fat: 1.68+/-0.21 vs. 1.26+/-0.18 liters, P < 0.01) using whole-body MRI despite no significant change in body weight, body mass index, or the waist-to-hip ratio. Interestingly, no changes in body fat content were found using anthropometry or impedance. There was a significant increase in high density lipoprotein cholesterol (1.58+/-0.06 vs. 1.66+/-0.08 mmol/L P < 0.02) following exercise although there were no changes in other blood lipids such as triglycerides. In summary, moderate aerobic exercise over a period of 6 mon resulted in a preferential loss in visceral fat in nonobese healthy women, and this may help to explain some of the health benefits associated with regular and moderate physical activity.

Adipose Tissue↗
PubMed2000

In vivo evaluation of the effects of continuous exercise on skeletal muscle triglycerides in trained humans.

Magnetic resonance spectroscopy (1H MRS) and imaging (MRI) were used to investigate the effects of a bout of moderate prolonged exercise on intra (IMCL)- and extramyocellular lipid (EMCL) utilization in the soleus, tibialis anterior, and gastrocnemius muscles of five trained human subjects. MRI and 1H MRS measurements were obtained before and after a 90 min run on a calibrated treadmill at a velocity corresponding to 64 +/- 1.5% of each subjects' maximal rate of oxygen consumption. There were significant decreases in IMCL following exercise in the tibialis (pre: 22.37 +/- 4.33 vs. post: 15.16 +/- 3.25 mmol/kg dry wt; P < 0.01) and soleus (pre: 36.93 +/- 1.45 vs. post: 29.85 +/- 2.44 mmol/kg dry wt; P < 0.01) muscles. There was also a decrease in the gastrocnemius muscle, although this did not reach the level of significance (pre: 33.78 +/- 5.35 vs. post: 28.48 +/- 5.44 mmol/kg dry weight; P < 0.10). No significant changes were observed in EMCL or subcutaneous fat. In conclusion, this study showed that IMCL were significantly utilized in the tibialis and soleus muscles of aerobically endurance-trained humans. The absence of significant utilization of IMCL in the gastrocnemius may reflect differences in fiber type and/or intensity of contraction for each muscle group.

Adult↗
PubMed1999

Angiotensin-converting-enzyme gene insertion/deletion polymorphism and response to physical training.

BACKGROUND: The function of local renin-angiotensin systems in skeletal muscle and adipose tissue remains largely unknown. A polymorphism of the human angiotensin converting enzyme (ACE) gene has been identified in which the insertion (I) rather than deletion (D) allele is associated with lower ACE activity in body tissues and increased response to some aspects of physical training. We studied the association between the ACE gene insertion or deletion polymorphism and changes in body composition related to an intensive exercise programme, to investigate the metabolic effects of local human renin-angiotensin systems. METHODS: We used three independent methods (bioimpedance, multiple skinfold-thickness assessment of whole-body composition, magnetic resonance imaging of the mid-thigh) to study changes in body composition in young male army recruits over 10 weeks of intensive physical training. FINDINGS: Participants with the II genotype had a greater anabolic response than those with one or more D alleles for fat mass (0.55 vs -0.20 kg, p=0.04 by bioimpedance) and non-fat mass (1.31 vs -0.15 kg, p=0.01 by bioimpedance). Changes in body morphology with training measured by the other methods were also dependent on genotype. INTERPRETATION: II genotype, as a marker of low ACE activity in body tissues, may conserve a positive energy balance during rigorous training, which suggests enhanced metabolic efficiency. This finding may explain some of the survival and functional benefits of therapy with ACE inhibitors.

Adipose Tissue↗
PubMed1999

Cerebral ventricular asymmetry in schizophrenia: a high resolution 3D magnetic resonance imaging study.

Lateral ventricular volume asymmetries in schizophrenia were studied using high resolution 3D magnetic resonance imaging in conjunction with segmentation and quantitation techniques. Comparisons were made between two clinical syndromes that have been associated with opposite patterns of functional hemispheric activation, namely an active and a withdrawn syndrome. Ratios of both left to right ventricular volume and left to right ventricle-to-brain ratios differed significantly between the two groups. These results primarily reflected differences in the left ventricular volume, in keeping with previous reports which have usually implicated left hemispheric structural abnormalities in schizophrenia. It is suggested that a syndromal approach might help to resolve some of the inconsistencies in the existing literature on lateralised neuroanatomical differences in schizophrenia.

Adult↗
PubMed1999

Volumetric change of the lateral ventricles in the human brain following glucose loading.

Lateral ventricular volumes were monitored and quantified using accurately registered magnetic resonance images (MRIs) in six healthy individuals 30 min before and up to 4 h after ingestion of a glucose drink. The volume of the lateral ventricles increased by an average (+/- S.E.M.) of 2.4 +/- 0.4% as blood glucose levels rose from 4.8 +/- 0.2 mmol l-1 to 8.4 +/- 0.4 mmol l-1. This was followed by a peak decrease of 5.99 +/- 3.3% below initial fasting volumes as blood glucose levels fell to 5.0 +/- 0.3 mmol l-1. We suggest that the secondary volume decrease demonstrates a homeostatic process of brain volume regulation for which the mechanism remains uncertain.

Administration, Oral↗
PubMed1998

Two methods for semi-automated quantification of changes in ventricular volume and their use in schizophrenia.

Two semi-automated methods for quantification of ventricular volume change from baseline and follow-up magnetic resonance imaging scans have been developed. Technique 1 employs direct segmentation of the ventricles from both the scans using thresholding and contour extraction. Technique 2 operates on difference images produced by voxel based intensity subtraction of the baseline from the registered follow-up images. Here, all voxels with intensities above a noise threshold and in a restricted area are monitored to compute volumetric changes. In phantom measurements the first technique was accurate to 0.0046%, the second to 0.167% of the phantom volume. Results from normal volunteers was that the average ventricular volume changed by 1.52% and 1.54% for images acquired within 9 months using techniques 1 and 2, respectively. With schizophrenic patients mean change of 10.78% and 9.43% were found employing the first and second procedures, respectively. All measurements agreed with a radiologist's visual grading of the changes. Robust, objective, fast, easy-to-use, and fairly accurate procedures have been developed and validated to quantify volumetric changes.

Adult↗