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Biomedical subjects

M Shafi

Publications and source records attributed to M Shafi.

At least 19 recordsLinked to original sources
PubMed2005

Patterned firing of parietal cells in a haptic working memory task.

Abstract Cells in the somatosensory cortex of the monkey are known to exhibit sustained elevations of firing frequency during the short-term mnemonic retention of tactile information in a haptic delay task. In this study, we examine the possibility that those firing elevations are accompanied by changes in firing pattern. Patterns are identified by the application of a pattern-searching algorithm to the interspike intervals of spike trains. By sequential use of sets of pattern templates with a range of temporal resolutions, we find patterned activity in the majority of the cells investigated. In general, the degree of patterning significantly increases during active memory. Surrogate analysis suggests that the observed patterns may not be simple linear stochastic functions of instantaneous or average firing frequency. Therefore, during the active retention of a memorandum, the activity of a 'memory cell' may be characterized not only by changes in frequency but also by changes in pattern.

Action Potentials↗
PubMed2003

A survey of the safety of doctors driving home after a night 'on call'.

The 'on-call' system for doctors within the health service maintains a continuity of care. However, allowing doctors to drive home after a night on call may pose a public hazard. The aim of this survey was to assess doctors' opinions regarding the safety of driving without adequate sleep.

After-Hours Care↗
PubMed2000

Cutaneous and paranasal aspergillosis in an immunocompetent patient.

A 26-year-old Libyan woman presented with asymptomatic nodulo-ulcerative skin lesions present for 1 year. Three years prior to presentation, she had experienced a nasal discharge followed by the development of a nodule in the nasal cavity and a plaque on the hard palate. These lesions had gradually increased in size and ulcerated, resulting in perforation of the nasal septum and palate. Two years later, the patient noticed the appearance of skin lesions: a nodule on the right thumb and numerous nodulo-ulcerative lesions on the extremities. General physical examination was normal with no significant lymphadenopathy. Examination of the oral cavity revealed perforation of the distal nasal septum, with a perforated nodular plaque involving the entire palate, associated with subluxation of the upper incisors (Fig. 1a). On skin examination, multiple firm nodules and nodulo-ulcerative lesions with a central eschar and raised margins were observed. The lesions ranged in size from 0.5 to 5 cm and were distributed on the right hand and fingers, left upper arm (Fig. 1b), left calf, and right thigh. Routine laboratory investigations (liver function tests, serum calcium, electrolytes, lipid profile, urine and stool culture studies) were normal. Immunoelectrophoresis disclosed normal levels of immunoglobulins IgG, IgA, and IgM. Serologic studies for human immunodeficiency virus (HIV) and syphilis, and a tuberculin test, were all negative. A Giemsa-stained tissue smear was negative for Leishmania tropica organisms. Radiological studies disclosed a slight haziness of the maxillary sinuses with perforation of the nasal septum. A chest X-ray was normal. Histopathologic examination of biopsies taken from both the palate and from ulcerated and nonulcerated skin lesions was performed, and all showed similar findings. The biopsy of a nonulcerated skin lesion showed pseudoepitheliomatous epidermal hyperplasia with neutrophilic microabscesses (Fig. 2a). A dermal diffuse and nodular granulomatous mixed infiltrate of lymphocytes, histiocytes, giant cells, numerous eosinophils, and neutrophilic microabscesses was seen in all tissues examined. Septate hyphae were present both within giant cells and free in the dermis (Fig. 2b). The hyphae were branching at a 45 degrees angle and were positive on periodic acid-Schiff and Grocott methenamine silver stains (Fig. 2c). Fungal culture studies of material taken from an ulcerated skin lesion grew Aspergillus flavus. Blood cultures were negative for Aspergillus sp. or other microorganisms. The patient was treated with intravenous amphotericin B, but the medication was discontinued due to her intolerance to the drug. She was subsequently lost to follow-up.

Adult↗
PubMed1999

Xeroderma pigmentosum in Libya.

BACKGROUND: A preliminary study of 24 cases of xeroderma pigmentosum (XP) was presented in 1990 and later published in 1992. Since then we have seen 18 further cases. OBJECTIVE: To study the clinical profile of Libyan cases of XP. METHODS: With the help of a special protocol, all 42 cases (23 girls and 19 boys from 29 families) treated and followed between 1981 and 1994 were subjected to detailed analysis. RESULTS: A history of consanguinity was present in the parents of 39 patients. XP in Libya is characterized by a relatively high incidence (approximately 15-20 per million of the population), early onset of initial manifestations (median age, 12 months) and malignant tumors (median age, 8 years), severe ocular and oral lesions in a high percentage of patients, and early death (median age, 15.5 years). The malignant skin tumors seen were squamous cell carcinoma (SCC) in 23 patients, basal cell carcinoma (BCC) in 17 patients, and basosquamous carcinoma in two patients. Malignant melanoma was not seen, but lentigo maligna was found in one case. SCC of the tongue, carcinoma of the thyroid, and lymphatic leukemia affected individual patients. Subnormal physical growth was observed in six patients, but none of the patients had significant neurologic abnormalities. The results of etretinate therapy in nine patients revealed that it is an effective preventive agent against carcinogenesis, but not a curative one. CONCLUSIONS: Severe ophthalmic manifestations affected a higher percentage of patients at an early age. Malignant melanoma did not develop in any case, except for lentigo maligna in one patient.

Age of Onset↗
PubMed1997

Fine needle aspiration cytology in parotid lumps.

Over a period of two years, Fine Needle Aspiration Cytology (FNAC) was performed on 33 patients presenting with a parotid lump. Five patients were excluded as they were treated medically after FNAC report. The FNAC results of 28 cases were compared with histopathological diagnoses of surgically resected specimens. There were 8 true positive, 17 true negative, 1 false positive and 2 false negative cases. Sensitivity was 80%, specificity 94.4% and diagnostic accuracy 89.3%. FNAC is a simple quick, accurate and virtually complications free investigative modality. It is also helpful adjunct to assess preoperatively the suitability and extent of the surgical treatment.

Adolescent↗
PubMed1994

Cigarette smoking and histological outcome in women with mildly dyskaryotic cervical smears.

OBJECTIVE: To determine which patient related variables, available at the point of referral, predict the presence of high grade intraepithelial neoplasia when the smear result is mild dyskaryosis with or without co-existent koilocytosis. DESIGN: Multivariate analysis of prospective programme trial. SETTING: Academic Department Colposcopy clinics at Dudley Road Hospital, Birmingham, UK. SUBJECTS: One hundred and sixty-seven women, whose worst ever cervical smear was mild dyskaryosis with or without koilocytosis, referred to colposcopy clinics. All the women had complete data sets, as determined by the format of an ongoing programme, and all were treated by diathermy loop excision of the cervical transformation zone. MAIN OUTCOME MEASURES: Age, parity, contraceptive practice, smoking habit, duration of abnormal cytology and the grade of histology in the excised transformation zone. RESULTS: Forty-seven out of 78 (60%) smokers, compared with 18 out of 73 (25%) nonsmokers, had high grade disease. The other variables considered in the analysis were not significant or very weakly associated with histological grade when analysed in a univariate analysis. Stepwise logistic regression identified cigarette smoking as a powerful independent predictor of high grade disease. CONCLUSION: These data suggest a strong association between smoking and high grade intraepithelial neoplasia in a population of women whose worst ever smear report was mild dyskaryosis. Smoking is a variable that could be built into models to facilitate referral for colposcopic assessment.

Adolescent↗
PubMed1992

Xeroderma pigmentosum. A clinical study of 24 Libyan cases.

BACKGROUND: Despite a high incidence of xeroderma pigmentosum, there is no previous publication from Libya. OBJECTIVE: The purpose was to study the clinical profile of Libyan cases of xeroderma pigmentosum. METHODS: With the help of a special protocol, 24 cases of xeroderma pigmentosum treated between 1981 and 1990 were subjected to detailed analysis. RESULTS: The age of onset of initial manifestations ranged between 6 and 18 months whereas that of malignant lesions ranged from 2 to 10 years. Malignant lesions observed were squamous cell carcinoma in 15 patients, basal cell carcinoma in 12, and basosquamous carcinoma in 2 patients; squamous cell carcinoma of the tongue, carcinoma of the thyroid, and lymphatic leukemia affected individual cases. None of our patients developed malignant melanoma. Six patients have died; the age at death ranged between 9 and 18 years. A history of consanguinity in the parents of patients was recorded in all but two patients. CONCLUSION: We observed early onset of severe ophthalmic lesions affecting a higher percentage of the patients.

Adolescent↗
PubMed1992

The occurrence of IgA-nephropathy in patients with diabetes mellitus may not be coincidental: a report of five cases.

We describe five patients with IgA-nephropathy complicating diabetes mellitus. In four cases, diabetic glomerulosclerosis was present at the same time. One patient suffered from dermatitis herpetiformis. The observation of the present five cases together with the notion of an increased prevalence in diabetes mellitus of celiac disease and dermatitis herpetiformis suggests that the occurrence of IgA-nephropathy in diabetic patients is not mere coincidence.

Aged↗