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Biomedical subjects

A Hassan

Publications and source records attributed to A Hassan.

At least 91 records · Page 5Linked to original sources
PubMed1996

The role of surveillance in a 'high risk' approach to the elimination of neonatal tetanus in Egypt.

BACKGROUND: Despite an international resolution to eliminate neonatal tetanus (NT) as a public health problem by the year 1995, 490000 cases occurred worldwide in 1994. An analysis of the NT elimination programme in Egypt was conducted to determine the utility of a 'high risk' approach in controlling this disease. METHODS: Three of the indicators for identifying districts at high risk of NT were evaluated. NT rates, tetanus toxoid coverage (TT2+), and urban or rural status. The reduction in NT incidence from 1992 to 1994 was compared between those high risk districts (> or = 1 NT case/1000 live births in 1992) which did or did not conduct supplementary immunization (P = 0.035). RESULTS: In a multivariate analysis, the strongest indicator of the NT risk in a district was the presence of > or = 1 case/1000 live births in the previous year (Rate ratios [RR] = 3.34 in 1993 and 3.07 in 1994, P < 0.001). The TT2+ coverage was not a reliable indicator of NT risk. Urban areas had a significantly lower risk than rural areas (RR = 0.62) in 1993 and 0.49 in 1994, P < 0.001). The decline in NT rates was greatest in the 'high risk' districts that conducted supplementary immunization in both 1993 and 1994. CONCLUSIONS: Although tetanus toxoid immunization of pregnant women will protect newborns from NT, TT2+ coverage calculated by the administrative method may not reflect a population's risk of NT. Surveillance data, however, can be used to identify areas where the ongoing risk NT is high. Conducting supplementary immunization in areas that are identified as 'high risk' on the basis of previous NT rates can significantly reduce the number of cases in subsequent years.

Egypt↗
PubMed1996

Endothelial vasodilator production by uterine and systemic arteries. I. Effects of ANG II on PGI2 and NO in pregnancy.

Uterine vasculature is less responsive than systemic vasculature to angiotensin II (ANG II)-induced vasoconstriction. We hypothesized that pregnancy augments basal and ANG II-stimulated endothelial prostacyclin (PGI2) and/or nitric oxide (NO) production, which locally increase vascular smooth muscle (VSM) adenosine 3',5'-cyclic monophosphate (cAMP) and guanosine 3',5'-cyclic monophosphate (cGMP), respectively. Uterine (UA) and systemic arteries (SA) from pregnant (P) and nonpregnant (NP) sheep were incubated with isobutylmethylxanthine. Basal PGI2, cAMP, and cGMP production was 2.4-, 1.6-, and 5.9-fold greater (P < 0.01) in UA from P vs. NP sheep; endothelium removal lowered (P < 0.05) values 69, 44, and 88%. Basal SA PGI2 and cAMP, but not cGMP, also were elevated by pregnancy. Indomethacin (Indo; 100 microM) decreased PGI2 and cAMP, but not cGMP production; N omega-nitro-L-arginine methyl ester (L-NAME; 10 microM) and methylene blue (MB, 10 microM) only decreased cGMP. Basal UA, but not SA, NO synthase activity (conversion of [3H]arginine to [3H]citrulline), was 1.8-fold higher in pregnancy and decreased (P < 0.01) after endothelium removal and with L-NAME. ANG II (50 nM) increased PGI2 (86%) and cAMP (56%) production only in UA from P sheep (P < 0.05); this was abolished by endothelium removal or Indo. ANG II also increased (P < 0.01) cGMP production by UA from both groups but only by SA from P ewes; this was absent in denuded, L-NAME-, or MB-treated vessels. Stimulation of VSM cGMP production with sodium nitroprusside (50 microM) was inhibited by MB, but not L-NAME or endothelium removal. In pregnancy, endothelial PGI2 and NO production are enhanced and may contribute to attenuated ANG II vasoconstriction via VSM cAMP and cGMP.

Angiotensin II↗
PubMed1996

Gene transfer by naked DNA into adult mouse brain.

Nonviral gene transfer into the central nervous system could provide a basis for therapeutic uses and fundamental research. We show that naked DNA injected intracerebrally into the mouse brain can provide expression of a reporter protein. Expression is dose dependent, being maximal for 150 mu g DNA injected. We observed less than 5 days expression of the luciferase transgene, which is not improved with plasmid preparations virtually free of lipopolysaccharide. Thus, the adult brain behaves as striated muscle for naked DNA uptake and transcription, albeit at a much lower efficiency. In neither adult brain nor muscle did complexation of DNA with cationic lipid improve transgene expression. Double immunolabeling using cell-specific markers shows that both neurons and glia are transfected by naked DNA gene transfer methodology.

Animals↗
PubMed1995

Formation in vitro of the 3,4,6-trihydroxyphenylalanine quinone cofactor.

An Escherichia coli K-12 2-phenylethylamine oxidase gene with a mutated leader sequence region produced a largely inactive form of the enzyme in the cytoplasm. This form of the enzyme was activated 30-50-fold on incubation at 30 degrees C in the absence of any added cofactors. After activation the enzyme contained a quinone which was not detected in the non-activated form. This is the first report of the formation in vitro of any quinoenzyme cofactor.

Amine Oxidase (Copper-Containing)↗
PubMed1995

Head injuries in lateral impact collisions.

Individual non-minor injuries (Abbreviated Injury Scale (AIS) > or = 2) to the head that occurred to belted and unbelted drivers and front seat passengers on the stuck side of impacted vehicles were examined. Injury type, injury combination, collision severity in relation to type of injury as well as contact sources were assessed. Forty-eight percent of injuries were moderate in severity (AIS 2). The most common type of injury was the diffuse brain injury, typically marked by a short period of unconsciousness, which occurred in collisions of lower severity than focal brain and skull fracture injuries. One-hundred and five out of 216 (48.6%) of contact sources for all injury types originated from outside the vehicle and such exterior sources were more likely to result in high severity injuries. Thirty percent of injuries resulted from head contacts with other vehicles. The most frequent vehicle interior contact source was the side window glass. Diffuse injuries tended to occur independently of other injury types and were more likely to originate from an interior rather than exterior contact. Preventative measures for head injury reduction in lateral collisions are discussed. Overall, the data show that proposed and present European and U.S. lateral impact test methods do not address many head injury problems such as those included in this study.

Abbreviated Injury Scale↗
PubMed1995

High prevalence of hepatitis C virus among urban and rural population groups in Egypt.

Hepatitis C is a major health problem for Egypt. The aim of this study was to determine the seroprevalence of antibodies to hepatitis C virus among different population groups living in urban and in two different rural areas (Suez Canal and North Sinai) of Egypt. Secondary objectives were to study the possible association between multiple blood transfusions, haemodialysis or Schistosomiasis and the seroprevalence of antibodies to hepatitis C. A seroprevalence of hepatitis C virus in the urban blood donor population of 14.5% was found, confirming other reports. In the two rural areas of the Suez Canal and the North Sinai the seroprevalence was 14.4% and 15.5% respectively, showing a comparable seroprevalence in these three different populations. The seroprevalence was 70.4% in haemodialysis patients, 7.7% in health care workers, and 75.6% in thalassaemic children, thus a seroprevalence among multitransfused or haemodialysed patients comparable to the one described in many other countries. Schistomiasis does not seem to play a role in the seroprevalence of this disease in Egypt.

Adult↗
PubMed1995

[Dynamic obstruction of the left ventricular outflow tract by prosthesis dysfunction].

We report on a case of dynamic left ventricular (LV) outflow tract obstruction combined with a prosthetic valve dysfunction 13 years following mitral valve replacement with a Hancock bioprosthesis in a 46-year-old patient. Previously, repeated echocardiographic controls had been performed at regular intervals and the prosthesis had been found to be oversized and seated in abnormal position, with projection of the struts into the LV outflow tract. Moreover, a mild chronic LV outflow tract obstruction had been diagnosed upon intermittent findings of relatively high velocity in the outflow tract. Clinically, however, the patient had been stable and the function of the prosthesis had been good. With the onset of the mitral regurgitation due to prosthesis failure, a dynamic obstruction to LV outflow occurred, with severe narrowing of the LV outflow tract by a strut of the bioprosthesis during systole. Subsequently, a low cardiac output syndrome developed. The patient was referred for a mitral valve reoperation. The valve was replaced with a Sorin Bileaflet Carbon prosthesis. On the setting of a mild chronic LV outflow obstruction due to the oversized prosthesis and its abnormal position, hypercontractile cardiac function as a result of mitral regurgitation may have caused the dynamic and symptomatic LV outflow tract obstruction.

Bioprosthesis↗
PubMed1994

Precocious auto-induction of thyroid hormone receptors in embryonic chick hypothalamic neurons.

Qualitative immunocytochemical and quantitative autoradiographic approaches were used to examine the presence of thyroid hormone receptor (TR) proteins in embryonic chick hypothalamic cultures and the effect of T3 on their expression. We used antibodies raised against rat TRs having first verified that they recognised nuclear T3 binding proteins in extracts from chick brains. TRs were expressed in embryonic hypothalamic neurons from 6 day-old chick embryos maintained 4 days in vitro, and their expression was up-regulated by T3. This demonstration of TRs in embryonic hypothalamic neurons suggests that a physiological mechanism for early regulation of the hypothalamic neuropeptide, thyrotropin releasing hormone, is installed prior to the onset of thyroid function.

Animals↗
PubMed1994

Management and follow-up of harlequin siblings.

Harlequin fetus is a rare clinical entity, and survival of affected infants beyond the first year of life is uncommon. Management involves intensive care of the skin and eyes, close monitoring of fluid and electrolyte status, constant support and counselling of parents, and surveillance against infection and side-effects of medication. A well-coordinated multidisciplinary approach can prolong survival beyond the neonatal period. We report our experiences in the management and follow-up of two successive harlequin siblings.

Administration, Topical↗
PubMed1993

Kinetics of Photofrin II in perifocal brain edema.

Photodynamic therapy is under intense investigation as a possible adjuvant for the treatment of malignant tumors of the central nervous system. It relies on the fact that photosensitizers are selectively taken up or retained by malignant tissue. However, most brain tumors are accompanied by substantial vasogenic edema as a consequence of blood-brain barrier disruption within the tumor, leading to extravasation and propagation of plasma constituents into the surrounding brain tissue. Systemically administered photosensitizers may enter healthy tissue together with the edema fluid, possibly leading to sensitization of tissues outside the tumor. To test this hypothesis, vasogenic edema was induced by cold injury to the cortex in rats. The edema thus obtained is highly reproducible and very similar to tumor-associated edema. Just after injury induction, Photofrin II (PF-II), a commonly used photosensitizing agent, was administered at a dose of 5 mg per kilogram of body weight along with fluorescein isothiocyanate (FITC)-labeled albumin to mark edema advancement. After 1, 4, 12, or 24 hours, the brains were removed and frozen, and cryosections were studied with high-sensitivity video fluorescence microscopy for edema extravasation within the lesion and propagation of PF-II into the surrounding gray matter. PF-II advanced with edema along the corpus callosum underlying the cortex to a distance of 5 mm from the lesion after 4 hours. With the exception of the lesion, PF-II fluorescence returned to baseline after 24 hours, indicating subsequent washout. Propagation was comparable to the spreading of FITC-marked albumin. The authors conclude that photosensitizers spread with edema, an observation that may be pertinent to a number of questions concerning photodynamic therapy of cerebral tumors.

Animals↗
PubMed1992

Genetic analyses in neurons and neural crest-derived post mitotic cells.

Cationic lipids are shown to be efficient DNA carriers for gene transfer into neurons and chromaffin cells. Chimeric genes containing the coding sequence for the bacterial gene chloramphenicol acetyl transferase (CAT), under various promoter sequences were used to estimate transfection efficiency and to analyse transcriptional mechanisms. Using a ubiquitously expressed construct (RSV-CAT), and an anti-CAT antibody to identify CAT positive cells transfection efficiency was found to be approximately 70% in cultures of hypothalamic neurons. Proenkephalin gene expression was studied in chromaffin cells by employing a chimeric gene containing the rat pro-enkephalin promoter fused to the CAT reporter gene. Using this model we show that the transfected gene is inducible by neurotransmitters and second messengers. The contribution of a specific kinase (protein kinase A, PKA) to proenkephalin gene regulation is analysed using this model system, and expression vectors coding for the catalytic subunit of PKA.

Animals↗
PubMed1991

[Role of beta thyroid hormone receptor in the modulation of the TRH transcription].

Two genes coding for thyroid hormone (T3) receptors (THR) have been identified: THR alpha and THR beta. To determine their transcriptional effects we transfected reporter genes expressing chloramphenicol acetyl transferase (CAT) alone or with vectors coding for THR alpha or THR beta in primary cultures of embryonic chick hypothalami. Transcription from a promotor containing a T3 Response Element (T3RE-CAT), was activated in the presence of tri-iodo thyronine (T3) and much reduced in the absence of the hormone. In contrast, in the absence of T3, transcription from the Thyrotropin releasing hormone (TRH) promoter (TRH-CAT) was much greater than in cultures grown with T3. In cotransfection experiments where THR alpha or THR beta was expressed with the TRH promoter construct, THR beta-dependent transcription, but not THR alpha-dependent transcription, was significantly reduced in the presence of T3.

Animals↗