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Biomedical subjects

A Riaz

Publications and source records attributed to A Riaz.

18 recordsLinked to original sources
PubMed2004

Effect of collection frequency on the semen quality of broiler breeder.

1. Seven 35-week-old Hubbard broiler breeder males were subjected to three semen collection frequencies either once every 2 d (48 h), daily (24 h) or twice daily (12 h). 2. Semen characteristics including motility, volume, concentration and sperm numbers per ejaculate were determined for each ejaculate. 3. Sperm motility was unaffected by collection interval, but semen volume was lower at 12 than 24h intervals. Sperm concentration was lower at 12 than 48h intervals. 4. At 24 and 48 h number of sperm per collection (1.7+/-0.2, 1.8+/-0.2 x 10(9)) were higher than at 12 h (1.2+/-0.1 x 10(9)). 5. The number of semen doses over a 6-d period increased linearly as the frequency of collection increased from once every 2 d to twice daily. 6. It is concluded that output was theoretically maximal at twice daily collection, but in practice not all cockerels may be able to maintain full performance with such a demanding regime.

Animals↗
PubMed2003

A novel form of pontocerebellar hypoplasia maps to chromosome 7q11-21.

OBJECTIVE: To describe a novel form of pontocerebellar hypoplasia (PCH) and map its genetic locus. BACKGROUND: PCH is a heterogeneous group of disorders that are characterized by abnormally small cerebellum and brainstem. Autosomal recessive inheritance has been implied in many cases, but no genetic loci have been mapped to date. METHODS: The authors studied a consanguineous family from the Sultanate of Oman with three siblings with a novel form of PCH. The authors performed clinical studies and linkage analysis of this pedigree. RESULTS: The clinical features of the affected children include developmental delay, progressive microcephaly with brachycephaly, seizures during the first year of life, hypotonia with hyperreflexia, short stature, and optic atrophy. Imaging studies showed a small pons and cerebellum, prominent sulci and lateral ventricles, and decreased cerebral white matter volume. A lack of dyskinesias distinguishes this pedigree from PCH type 2. Genetic studies of this family revealed evidence of significant linkage to chromosome 7q11-21 (maximum multipoint lod score 3.23). CONCLUSIONS: This pedigree represents a novel form of autosomal recessive PCH, which the authors propose to call cerebellar atrophy with progressive microcephaly (CLAM). This disorder maps to chromosome 7q11-21, and this locus was named CLAM. This report represents the first identification of a genetic locus for PCH.

Abnormalities, Multiple↗
PubMed2001

Outcome in patients with end-stage renal disease following heart or heart--lung transplantation receiving peritoneal dialysis.

BACKGROUND: End-stage renal disease (ESRD) complicates 5--10% of heart and heart--lung transplant patients. We report our experience of peritoneal dialysis (PD) in 17 such patients. METHODS: Between March 1995 and February 1999, 13 heart transplant and four heart--lung transplant patients (11 male, 6 female) joined our PD programme (10 continuous ambulatory PD, seven automated PD). Median time from heart or heart--lung transplantation to ESRD was 9 years (range 1--13 years), and median age at introduction of renal replacement therapy was 51 years (range 23--66 years). The frequency of exit-site infections, peritonitis, and PD survival (including technique failure and death) in the transplant group (TxP) was calculated retrospectively. These were compared with two contemporary control groups: PD patients immunosuppressed for other indications (ISP, n=19) and, all other patients recruited onto the PD programme (NISP, n=132). RESULTS: Median follow-up was 10 months (range 2--27 months) for TxP, 7 months (range 2--29 months) for ISP, and 14 months (range 1--48 months) for NISP groups. The frequency of exit-site infections was similar in each group: 1 in 26 months for TxP; 1 in 30 months for ISP, and 1 in 27 months for NISP (P=NS). The frequency of peritonitis was greater in the TxP group at 1 in 15 months, compared with 1 in 20 months for ISP and 1 in 29 months for NISP (TxP vs NISP, P<0.05). PD failure following infection was 23.5% for TxP, 10.5% for ISP, and 12.9% for NISP. Actuarial PD survival at 24 months was only 25.2% in the TxP group compared with 79% in the NISP group. There were no deaths related to immediate complications of PD. CONCLUSIONS: Increased risk of PD peritonitis and reduced PD survival is reported in this cohort of 17 heart and heart--lung recipients with ESRD. Nevertheless, for patients with severely impaired cardiac function, PD may still offer therapeutic advantage.

Adolescent↗
PubMed2000

Further delineation of the DOOR syndrome.

Two related sibships from an extended family have been observed with the features of the DOOR syndrome. These features included deafness, onychodystrophy, osteodystrophy, microcephaly, and global developmental retardation with progressive blindness. Seizures, which were associated with hypsarrhythmia, were frequent and difficult to control and ultimately were the cause of death in two patients. An MRI brain scan of case 1 showed a number of abnormalities including markedly reduced myelination. The urine organic acid analysis showed a ten-fold increase of 2-oxoglutarate. In one patient the placenta was noted to have multiple fluid filled cysts, which is a feature reported in other metabolic diseases. It is suggested that there may be genetic heterogeneity in the syndrome, and the presence of increased 2-oxoglutarate is associated with a more severe phenotype which is frequently lethal.

Abnormalities, Multiple↗
PubMed1999

A novel method of guideline development for the diagnosis and management of mild to moderate hypertension.

BACKGROUND: There are large numbers of clinical guidelines available covering many clinical areas. However, the variable quality of their content has meant that doctors may have been offered advice that has been poorly researched or is of a conflicting nature. It has been shown that local involvement in guideline development increases the likelihood of their use. AIM: To develop a guideline to be used by general practitioners in six practices in Birmingham from existing evidence-based guidelines. METHOD: Recommendations from the four most cited international hypertension guidelines, and the more recently published New Zealand guidelines, were divided into subject areas and tabulated to facilitate direct comparison. Where there was complete or majority (> or = 3/5) agreement, the recommendation was taken as acceptable for inclusion in the new guideline. Where there was disagreement (< or = 2/5), recommendations were based on the best available evidence following a further MEDLINE literature search and critical appraisal of the relevant literature. Each recommendation was accompanied by a grade of evidence (A-D), as defined by the Canadian Hypertension Society, and an 'action required' statement of either 'must', 'should', or 'could', based on the Eli-Lilly National Clinical Audit Centre Hypertension Audit criteria. The recommendations were summarized into a guideline algorithm and a supporting document. The final format of both parts of the guideline was decided after consultation with the practice teams. The practices individually decided on methods of data collection. RESULTS: The guideline was presented as a double-sided, A4 laminated sheet and an A4 bound supporting document containing a synthesis of the original guidelines in tabular form, a table of the resulting recommendations, and appendices of current literature reviews on areas of disagreement. The content of the final Birmingham Clinical Effectiveness Group (BCEG) guideline differed minimally from any of the original guidelines. CONCLUSION: The main strength of this method of guideline development may lie, not in the actual content of the resulting guideline, but in the strength of ownership felt by the BCEG and the practices following its development. While the full process is unlikely to be possible for general practitioners working outside an academic environment, the techniques used could provide a framework for practitioners to adapt national and international guidelines for use at a local level.

Decision Trees↗
PubMed1998

Ethanol and neurotransmitter interactions--from molecular to integrative effects.

There is extensive evidence that ethanol interacts with a variety of neurotransmitters. Considerable research indicates that the major actions of ethanol involve enhancement of the effects of gamma-aminobutyric acid (GABA) at GABAA receptors and blockade of the NMDA subtype of excitatory amino acid (EAA) receptor. Ethanol increases GABAA receptor-mediated inhibition, but this does not occur in all brain regions, all cell types in the same region, nor at all GABAA receptor sites on the same neuron, nor across species in the same brain region. The molecular basis for the selectivity of the action of ethanol on GaBAA receptors has been proposed to involve a combination of benzodiazepine subtype, beta 2 subunit, and a splice variant of the gamma 2 subunit, but substantial controversy on this issue currently remains. Chronic ethanol administration results in tolerance, dependence, and an ethanol withdrawal (ETX) syndrome, which are mediated, in part, by desensitization and/or down-regulation of GABAA receptors. This decrease in ethanol action may involve changes in subunit expression in selected brain areas, but these data are complex and somewhat contradictory at present. The sensitivity of NMDA receptors to ethanol block is proposed to involve the NMDAR2B subunit in certain brain regions, but this subunit does not appear to be the sole determinant of this interaction. Tolerance to ethanol results in enhanced EAA neurotransmission and NMDA receptor upregulation, which appears to involve selective increases in NMDAR2B subunit levels and other molecular changes in specific brain loci. During ETX a variety of symptoms are seen, including susceptibility to seizures. In rodents these seizures are readily triggered by sound (audiogenic seizures). The neuronal network required for these seizures is contained primarily in certain brain stem structures. Specific nuclei appear to play a hierarchical role in generating each stereotypical behavioral phases of the convulsion. Thus, the inferior colliculus acts to initiate these seizures, and a decrease in effectiveness of GABA-mediated inhibition in these neurons is a major initiation mechanism. The deep layers of superior colliculus are implicated in generation of the wild running behavior. The pontine reticular formation, substantia nigra and periaqueductal gray are implicated in generation of the tonic-clonic seizure behavior. The mechanisms involved in the recruitment of neurons within each network nucleus into the seizure circuit have been proposed to require activation of a critical mass of neurons. Achievement of critical mass may involve excess EAA-mediated synaptic neurotransmission due, in part, to upregulation as well as other phenomena, including volume (non-synaptic diffusion) neurotransmission. Effects of ETX on receptors observed in vitro may undergo amplification in vivo to allow the excess EAA action to be magnified sufficiently to produce synchronization of neuronal firing, allowing participation of the nucleus in seizure generation. GABA-mediated inhibition, which normally acts to limit excitation, is diminished in effectiveness during ETX, and further intensifies this excitation.

Animals↗
PubMed1998

A study in contrasts: eligibility criteria in a twenty-year sample of NSABP and POG clinical trials. National Surgical Adjuvant Breast and Bowel Program. Pediatric Oncology Group.

We studied changes in eligibility criteria--the largest impediment to patient accrual--in two samples of clinical trials. Trials from the NSABP (National Surgical Adjuvant Breast and Bowel Program) and POG (Pediatric Oncology Group) were analyzed. After eliminating duplications, the criteria in each protocol were enumerated and classified according to a novel schema. NSABP trials contained significantly more criteria than POG trials, and added precision criteria (making study populations homogeneous) at a faster rate than POG studies. The difference between NSABP studies (explanatory trials) and POG studies (pragmatic trials) suggest that large numbers of eligibility criteria are not necessary for quality studies. We recommend that: (1) the inclusion/exclusion criteria distinction be abandoned; (2) eligibility criteria be explicitly justified; (3) the need for each criterion be assessed when new trials are planned; (4) criteria in phase III trials restricting patient accrual be minimized; and (5) further research be done to assess the impact of criteria on generalizability.

Breast Neoplasms↗
PubMed1998

Patient attitudes to over-the-counter drugs and possible professional responses to self-medication.

BACKGROUND: There is a paucity of research about patients' attitudes towards their doctor's recommending over-the-counter (OTC) remedies or about how patients respond to the doctor's suggestion to try an OTC remedy. OBJECTIVES: The aim of this study was to ascertain the attitudes of patients to OTC drugs. METHODS: 505 consecutive patients from each of six participating practices filled in a questionnaire. RESULTS: A total of 2765 (91.3%) patients responded. The responses from 2624 patients were from adults and are presented here. Based on the number of valid responses to each question, 53.8% of these patients were exempt from prescription charges, 55.1% took regular prescribed medication and 24.6% stated that they used OTC remedies regularly. There were generally positive attitudes to doctors enquiring about prior OTC use as well as to doctors making OTC recommendations in the consultation. However, patients expressed fairly negative attitudes towards pharmacists making generic substitutions and were even more hostile to the idea that pharmacists should make therapeutic substitutions. CONCLUSION: In conclusion, GPs should consider asking their patients regularly about their use of OTC medicines and also consider recommending OTC use if this is cheaper than FP10s. However, the public at present do not appear to be prepared for interventions by the pharmacist.

Adolescent↗
PubMed1997

Fibrolamellar hepatocellular carcinoma: results of partial liver resection.

AIM: To assess the results of partial hepatic resection in the treatment of fibrolamellar hepatocellular carcinoma. PATIENTS AND RESULTS: We present six cases of Fibrolamellar hepatocellular carcinoma treated by partial hepatic resection. There were five females and one male with a mean age of 20 (2.6) yr. Five patients were stage IVA and 1 IVB based on the Union International Against Cancer Classification. Two patients, due to recurrent disease, needed further pulmonary resection and a hilar lymphadenectomy. All six cases underwent major resection, three with vascular reconstruction. No operative mortality was recorded; half of the patients displayed some degree of morbidity. One patient died six months after the operation and the rest are alive at 78, 41, 24, 12 and 9 months. We believe that even in advanced cases, an aggressive surgical policy even with vascular reconstruction is justified in patients with fibrolamellar hepatocellular carcinoma.

Adolescent↗
PubMed1995

Ethanol withdrawal induces increased firing in inferior colliculus neurons associated with audiogenic seizure susceptibility.

Ethanol withdrawal (ETX) in ethanol-dependent rats results in susceptibility to seizures, including generalized tonic-clonic audiogenic seizures (AGS). The inferior colliculus (IC) is strongly implicated in AGS initiation during ETX, but IC neuronal mechanisms subserving AGS are unclear. The present study examined IC (central nucleus) single neuronal firing during repeated (4 day) intragastric ethanol administration and during ETX. This involved microwire electrodes implanted chronically into freely moving rats and acoustic stimulation in intensities up to 105 dB SPL. During initial ethanol administration the animals were stuporous, and IC spontaneous neuronal firing and acoustically evoked firing at high stimulus intensities were significantly reduced. This firing reduction is consistent with the action of ethanol to enhance gamma-aminobutyric acid (GABA)-mediated inhibition, which is prominent in IC neurons at high stimulus intensities. During ETX the animals were agitated, and spontaneous IC neuronal firing and acoustically evoked firing at all stimulus intensities were significantly increased during the period of AGS susceptibility. Previous studies indicate that IC neuronal responses are tightly regulated by GABA and glutamate. The IC firing increases during ETX in the present study may involve the down-regulation of GABAA receptors and supersensitivity of glutamate receptors reported to occur during ETX. Previous studies also indicate that focal blockade of GABAA receptors or activation of glutamate receptors produces AGS susceptibility in normal rats. Therefore, the IC neuronal firing increases observed in the present study may play a critical role in initiation of AGS during ethanol withdrawal.

Acoustic Stimulation↗
PubMed1994

Increased responsiveness of pontine reticular formation neurons associated with audiogenic seizure susceptibility during ethanol withdrawal.

Susceptibility to audiogenic seizures (AGS) is observed during ethanol withdrawal (ETX). The pontine reticular formation (PRF) is implicated in the propagation pathway for AGS during ETX. The present study examined the changes in single PRF neuronal firing patterns produced by ethanol and during ETX following repeated intragastrically administered ethanol. Microwire electrode bundles were implanted into PRF and single neuronal responses in freely moving rats were examined. During initial ethanol administration the animals were stuporous, and spontaneous and acoustically-evoked PRF neuronal firing were reduced significantly. During ETX the animals were susceptible to AGS and displayed agitated and irritable behavior. At this time a significant increase in spontaneous and acoustically-evoked PRF neuronal firing was observed. Repetition-induced response attenuation (habituation) of PRF neuronal responses was significantly diminished during ETX, leading to an exaggerated acoustic startle response, which may be a physiological basis for AGS. Previous reports indicate that ethanol enhances the effects of GABA and decreases the effects of glutamate. The PRF neuronal firing increases during EXT in the present study may involve the down-regulation of GABAA receptors and supesensitivity of glutamate receptors reported to occur during ETX, which could contribute to AGS susceptibility. The PRF neuronal firing increases observed in the present study in concord with previous observation of AGS blockade by PRF microinjections during ETX further support an important role of this brain region in the propagation of AGS during ethanol withdrawal.

Acoustic Stimulation↗
PubMed1994

Seizures during ethanol withdrawal are blocked by focal microinjection of excitant amino acid antagonists into the inferior colliculus and pontine reticular formation.

Physical dependence on ethanol can result in seizure susceptibility during ethanol withdrawal. In rats, generalized tonic-clonic seizures are precipitated by auditory stimulation during the ethanol withdrawal syndrome. Excitant amino acids (EAAs) are implicated as neurotransmitters in the inferior colliculus and the brain stem reticular formation, which play important roles in the neuronal network for genetic models of audiogenic seizures (AGSs). Ethanol blocks the actions of EAAs in various brain regions, including the inferior colliculus. In this study, dependence was produced by intragastric administration of ethanol for 4 days. During ethanol withdrawal, AGSs were blocked by systemic administration of competitive or noncompetitive NMDA antagonists 3-((+/-)-2-carboxypiperazin-4-yl)-propyl-1-phosphonic acid (CPP) or dizocilpine (MK-801). Focal microinjections of NMDA or non-NMDA antagonists into the inferior colliculus or the pontine reticular formation also inhibited AGSs. MK-801 was the most potent anticonvulsant systemically. When injected into the inferior colliculus, CPP had a more potent anticonvulsant effect than either MK-801 or the non-NMDA antagonist 6-cyano-7-nitroquinoxaline-2,3-dione. The inferior colliculus was more sensitive than the pontine reticular formation to the anticonvulsant effects of both competitive NMDA and non-NMDA antagonists. The results of the present support the idea that continued ethanol administration may lead to development of supersensitivity to the action of EAAs in inferior colliculus and pontine reticular formation neurons. This may be a critical mechanism subserving AGS susceptibility during ethanol withdrawal.

Acoustic Stimulation↗
PubMed1992

Glutamate in the inferior colliculus plays a critical role in audiogenic seizure initiation.

Alterations of excitant amino acid (EAA) action are implicated in seizure susceptibility in the genetically epilepsy-prone rat (GEPR). The inferior colliculus (IC) is critical for audiogenic seizure (AGS) initiation in the GEPR. The present study observed that bilateral microinjection into the IC of L-canaline, a glutamate synthesis inhibitor, decreased AGS severity in the GEPR and also decreased potassium-evoked release of glutamate from IC slices. Bilateral microinjection of NMDA receptor antagonists, 2-amino-7-phosphonoheptanoate (AP7) or 3-((+/-)-2-carboxypiperazin-4-yl)-propyl-1-phosphonate (CPP) into IC blocked AGS, and an antagonist at non-NMDA EAA receptors, 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX), also blocked AGS. NMDA receptor antagonists were 5-200 times more effective than CNQX. Microinjection of a non-competitive NMDA receptor antagonist, dizocilpine (MK-801), into IC had little effect except with very high doses. Microinjection of CPP or AP7 into the IC blocked AGS at considerably lower doses as compared to pontine reticular formation (PRF). However, MK-801 attenuated AGS when microinjected into PRF at doses that were ineffective in IC. Systemically administered CPP blocked AGS and significantly reduced IC neuronal firing in the behaving GEPR, suggesting an important action of systemically administered NMDA receptor antagonists on brainstem auditory nuclei critical to AGS. The present results support a critical role for glutamate acting, in part, through NMDA receptors in IC in initiation of AGS.

Acoustic Stimulation↗
PubMed1979

Idiopathic subclinical enteropathy in southern Iran.

A study of 100 normal subjects from villages in southern Iran revealed that almost one third of this population had one (or more) absorptive or morphological abnormality of the small-bowel mucosa. The finding of morphologically normal bowel mucosa in stillborn fetuses and in newborns who died within two weeks of birth was consistent with the possibility that the abnormalities noted in the village population were postnatally acquired. Finally, speculations are offered regarding the relationship of idiopathic enteropathy and "immunoproliferative small intestinal disease," which is often seen in the region.

Adolescent↗
PubMed1978

Preoperative angiographic diagnosis of small bowel leiomyomas.

Two patients with gastrointestinal (GI) tract bleeding underwent preoperative selective visceral arteriography that demonstrated small-bowel tumors compatible with leiomyoma. A review of the material indicates that 42% of patients with small-bowel leiomyomas also have GI tract bleeding. Arteriography is valuable in obtaining a preoperative diagnosis.

Adult↗