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Biomedical subjects

H Chana

Publications and source records attributed to H Chana.

13 recordsLinked to original sources
PubMed2003

[An unusual case of major restriction of eye motility: severe myopia].

Severe restrictive disorders of ocular motility are rarely described in high myopia. Their cause is still unknown. Several theories have been suggested: structural changes in the ocular muscles, sixth-nerve palsy or an elongation of the ocular globe. We report the case of a 44 years old man with high myopia of the left eye and disturbed ocular motility. Medical imaging techniques (echography, CT, MRI) allowed us to objectify the cause of ocular motility problem.

Adult↗
PubMed2002

[Olfactory esthesioneuroblastoma with an ophtalmological presentation: a case report].

Esthesioneuroblastoma (ENB) is a rare malignant tumor, which develops from the olfactory neuroepithelium and is one of the rarest tumors of the nasal cavity. Revelation by ocular signs is unusual. We report the original observation of a case of ENB of the olfactive placodes in a 28-year-old adult discovered during exophthalmia. The authors studied the clinical, radiological, pathological, and therapeutic aspects. ENB should not be forgotten in case of unilateral tumorous exophthalmia associating rhinological signs.

Adult↗
PubMed2000

Clinical evaluation of resin-bonded gold alloy veneers.

STATEMENT OF PROBLEM: Clinical performance of resin-bonded alumina-abraded type III cast gold alloy veneers has not been reported. PURPOSE: This retrospective study evaluated the survival of such restorations for the management of tooth wear and other restorative problems. MATERIAL AND METHOD: This clinical study evaluated 25 patients between 14 and 60 years of age treated with a total of 158 cast gold veneers cemented with Panavia Ex cement. Restorations placed between January 1990 and February 1996 (mean age 48 months) were evaluated. Factors, including age, gender, operator, site, design, the extent of dentin exposure, the presence of previous restorations, dynamic and static occlusion, rubber dam, cause, and methods of interocclusal space creation, were evaluated with Cox regression. Survival probability was evaluated with Kaplan-Meier analyses. Significance was taken as P <.05. RESULTS: Failures occurred for 7.6% of restorations in 28% of patients. Alumina-abraded gold alloys cemented with Panavia Ex cement had an estimated 89% survival probability at 60 months using Kaplan-Meier analyses. The only variable to statistically influence survival was operator (P <.0001). Operator differences were due to a single operator who placed only 2 restorations in the same patient, both of which failed unusually quickly. CONCLUSION: Resin-bonded alumina-abraded type III cast gold alloys can be successfully used to restore both anterior and posterior teeth and were associated with an estimated 89% survival probability at 60 months.

Adolescent↗
PubMed2000

The occlusal management of maxillary anterior single-unit implant-supported restorations.

This paper, with the aid of clinical examples, highlights some of the common occlusal problems that can be associated with maxillary anterior single-unit implant-supported restorations. The authors stress the importance of thorough pre-operative planning to identify any likely occlusal problems. This allows patients to be fully informed of the impact of any necessary clinical compromise and of the need for and nature of modifications to the natural dentition.

Adult↗
PubMed1998

Carnosine protects proteins against methylglyoxal-mediated modifications.

Methylglyoxal (MG) (pyruvaldehyde) is an endogenous metabolite which is present in increased concentrations in diabetics and implicated in formation of advanced glycosylation end-products (AGEs) and secondary diabetic complications. Carnosine (beta-alanyl-L-histidine) is normally present in long-lived tissues at concentrations up to 20 mM in humans. Previous studies showed that carnosine can protect proteins against aldehyde-containing cross-linking agents such as aldose and ketose hexose and triose sugars, and malon-dialdehyde, the lipid peroxidation product. Here we examine whether carnosine can protect protein exposed to MG. Our results show that carnosine readily reacts with MG thereby inhibiting MG-mediated protein modification as revealed electrophoretically. We also investigated whether carnosine could intervene when proteins were exposed to an MG-induced AGE (i.e. lysine incubated with MG). Our results show that carnosine can inhibit protein modification induced by a lysine-MG-AGE; this suggests a second intervention site for carnosine and emphasizes its potential as a possible non-toxic modulator of diabetic complications.

Carnosine↗
PubMed1998

Degradation of a silver point in association with endodontic infection.

This paper describes an unusual clinical report of degradation of an endodontic silver point within the root canal of a lower right first premolar. Its apical portion was found to be degrading and at one stage a small portion became separated from its main body and was displaced apically. The tooth, despite past apical surgery, displayed signs of endodontic failure. Conventional retreatment and removal of the silver point improved the endodontic problems associated with this tooth. The silver point was analysed using both scanning electron microscopy and x-ray microanalyses. These tests revealed that the silver point had deteriorated significantly with a surface coating of a silver-chloride salt. Microleakage with infection and galvanic reaction are possible hypotheses as to the reason for the degradation of the silver point. Although other reports have demonstrated corrosion of silver points, this method of presentation appears unique.

Biodegradation, Environmental↗
PubMed1998

Young adult patients with established dental erosion--what should be done?

This clinical paper discusses the problem of managing established erosion in the young patient. For a significant number of these patients it is not possible to establish conclusively the erosive source. Intermediate composite restorations, in addition to the use of normal preventive measures, can be used to protect eroded teeth from further damage. The main goal of such restorations is to protect the viability of the worst-affected teeth until such time as the aetiological factors can be identified and controlled. They can also improve overall aesthetics and create interocclusal space.

Adolescent↗
PubMed1994

Transplacental IgG subclass concentrations in pregnancies at risk of haemolytic disease of the newborn.

The relationship of haemolytic disease of the newborn (HDN) to the transplacental passage of the four IgG subclasses was assessed at various gestational ages by comparing the maternal and fetal IgG subclass concentrations in 34 pregnancies at risk of HDN with those in 30 pregnancies not at risk. Higher maternal and fetal IgG1 levels were attained in pregnancies at risk of HDN than in pregnancies not at risk. In contrast, a slight decrease in maternal IgG2 and IgG4 levels occurred in pregnancies at risk of HDN, as compared with a slight rise in maternal IgG2 and IgG4 levels in pregnancies not at risk of HDN. Changes in fetal IgG2 and 4 concentrations in either type of pregnancy were very similar, showing only slight increases between the 19th and 34th week of gestation. A slight decrease in maternal IgG3 occurred in both types of pregnancy. In contrast, higher and fairly steady levels of fetal IgG3 were observed in fetuses not at risk of HDN throughout gestation, when compared with those in 'at risk' pregnancies. However, the statistical reliability of these results is not clear since only small numbers of samples were tested and because wide variations in IgG concentrations were observed. The IgG subclass concentrations in 50 paired maternal and cord blood samples were also measured and revealed that IgG1 levels were substantially higher in cord rather than maternal blood; cord and maternal IgG2, 3 and 4 levels, on the other hand, were fairly similar.

Erythroblastosis, Fetal↗
PubMed1994

Prenatal determination of human platelet antigen type using DNA amplification following amniocentesis.

OBJECTIVES: To demonstrate that fetal human platelet antigen (HPA1) type can be determined, without the need for fetal blood sampling, by amplification of fetal DNA from amniotic fluid cells using polymerase chain reaction and allele specific oligonucleotide hybridisation. DESIGN: Oligonucleotide DNA primers were designed to amplify a portion of the platelet glycoprotein GpIIIa gene which spans the site of the single base change which differentiates HPA1a from HPA1b. Specific oligonucleotides were designed to hybridise either to the amplified HPA1a allele or to the HPA1b allele. Amniotic cells were used as the DNA template both directly and following formal isolation of DNA. Fetal HPA1 type, determined by this method in fifteen pregnancies not at risk of perinatal alloimmune thrombocytopaenia, was compared to typing of fetal blood obtained following cordocentesis. The methodology was then used to HPA type the fetus in two pregnancies at risk of the disease. SETTING: Department of Molecular Biology and Centre for Fetal Care, Queen Charlotte's Hospital. SUBJECTS: Fifteen women undergoing amniocentesis and fetal blood sampling for other indications and two women at risk of perinatal allo-immune thrombocytopaenia whose partners were heterozygotes. RESULTS: In the 15 control cases and the two clinical cases, determination of fetal HPA1 type from amniotic fluid cells agreed with typing of fetal blood. There was no difference in the efficiency of amplification from amniotic fluid cells directly or from isolated DNA. CONCLUSIONS: Fetal HPA type may be reliably determined by amplification of DNA from amniotic fluid cells, eliminating the need for fetal blood sampling or immunoglobulin administration when the fetus is HPA1a negative.

Amniocentesis↗
PubMed1994

Hepatocellular carcinoma metastatic to the orbit in an African patient.

Primary hepatocellular carcinoma rarely metastasizes to the orbit. We report a 19-year-old black man from Zimbabwe who had hepatomegaly and an orbital mass. An orbital biopsy suggested a diagnosis of hepatocellular carcinoma. Immunohistochemical stains supported the diagnosis. To our knowledge, this is only the second reported case of hepatocellular carcinoma metastasizing to the orbit and the first such reported case from Africa.

Adult↗
PubMed1992

Western blotting is a sensitive technique for the detection of anti-PlA1.

Western (immuno-) blotting was evaluated as a technique for anti-PlA1 detection, using untreated and chloroquine or low pH-treated platelets. Chloroquine-treated platelet membranes generated the cleanest blots, giving end-point titres of 4000-16,000 for three different anti-PlA1 sera. These titres were between three and eight doubling dilutions higher than those obtained in solid phase, ELISA or indirect immunofluorescence tests. Nitrocellulose strips used for blotting could be stored for at least six months at room temperature without significant loss of PlA1 activity. However, immunoblotting still failed to detect anti-PlA1 in the sera of four of fivePl (A1-) women whose infants were born with neonatal thrombocytopenia of probable alloimmune origin.

Antibodies↗
PubMed1983

[Gyrate atrophy of the choroid and retina with hyperornithinemia in an African family].

The authors report on a Kenyan family in which 4 of the 5 siblings were suffering from gyrate atrophy of the choroid and retina with hyperornithinemia. All the affected members of the family had myopia, hemeralopia, loss of vision and constricted visual fields but no cataract. To the authors' knowledge this is the first African family with gyrate atrophy to be reported.

Adolescent↗