Conjunctival flaps

PURPOSE: The authors reviewed their experience with total conjunctival flaps (TCF) and partial conjunctival flaps (PCF) for the past 5 years in 61 patients. METHODS: Forty-eight patients had TCF and 13 had PCF. Diagnoses for surgery included severe bullous keratopathy for chronic graft failure (not candidates for keratoplasty) (19), herpes zoster ophthalmicus (7), chronic ulcerative keratitis (14), neurotrophic keratitis (2), and herpes simplex keratitis (9). RESULTS: There were seven complications. Four flap retractions occurred in the TCF group, requiring resuturing in two. Three complications occurred in the PCF group. One patient had two flap retractions and recurrent ulceration, requiring tarsorrhaphy. One patient with PCF suffered a perforation after flap retraction, necessitating penetrating keratoplasty. CONCLUSION: The authors believe conjunctival flaps are underused and should be considered seriously for bullous keratopathy, neurotrophic keratitis, recalcitrant keratitis, and persistent nonhealing epithelial defects.     

Comparison of immunoaffinity chromatography enrichment and nuclease P1 procedures for 32P-postlabelling analysis of PAH-DNA adducts

32P-postlabelling analysis for detecting DNA adducts formed by polycyclic aromatic compounds is one of the most widely used techniques for assessing genotoxicity associated with these compounds. In cases where the formation of adducts is extremely low, a crucial step in the analysis is an enrichment procedure for adducts prior to the radiolabelling step. The nuclease P1 enhancement procedure is the most established and frequently used of these methods. An immunoaffinity procedure developed for class specific recognition for polycyclic aromatic hydrocarbon (PAH)-DNA adducts has therefore been compared with the nuclease P1 method for a range of DNA adducts formed by PAHs. The evaluation was carried out with skin DNA from mice treated topically with benzo[a]pyrene, 7,12-dimethylbenz[a]anthracene, 5-methylchrysene or chrysene. The immobilised antibody had the highest affinity for adducts structurally similar to the BPDE-I-deoxyguanosine adduct ([+/-]-N2-(7r,8t,9r-trihydroxy-7,8,9,10-tetrahydrobenzo[a]pyrene-1 0t-yl)-2'-deoxyguanosine) against which the antibody had been raised. Of the PAH-modified DNAs evaluated, the maximum adduct recovery was obtained for DNA containing the BPDE I-deoxyguanosine adduct. With DMBA-modified DNA, the profiles of adducts recovered from the column were similar when the column material was treated either with a digest of DMBA-modified DNA or with 32P-labelled DMBA adducts. I-compounds (endogenous adducts in tissue DNA of unexposed animals), which had similar chromatographic properties to PAH-DNA adducts, were not enriched by the immunoaffinity procedure. Compared to the simple nuclease P1 enhancement procedure, the immunoaffinity methods were lengthier and more labour intensive. Advantages of the immunoaffinity procedure include: specificity, allowing the selective detection of a certain class of adducts: efficient adduct enrichment, providing a viable alternative to other enrichment procedures; adequate sensitivity for model studies and the potential to purify adducts for further characterisation. However, as a general screen for detecting the formation of DNA adducts, the nuclease P1 procedure was viewed as the initial method of choice since it was capable of detecting a wider range of PAH-DNA adducts.     

Analysis of the regulatory phosphorylation site in Acanthamoeba myosin IC by using site-directed mutagenesis

The actin-activated ATPase activity of Acanthamoeba myosin IC is stimulated 15- to 20-fold by phosphorylation of Ser-329 in the heavy chain. In most myosins, either glutamate or aspartate occupies this position, which lies within a surface loop that forms part of the actomyosin interface. To investigate the apparent need for a negative charge at this site, we mutated Ser-329 to alanine, asparagine, aspartate, or glutamate and coexpressed the Flag-tagged wild-type or mutant heavy chain and light chain in baculovirus-infected insect cells. Recombinant wild-type myosin IC was indistinguishable from myosin IC purified from Acanthamoeba as determined by (i) the dependence of its actin-activated ATPase activity on heavy-chain phosphorylation, (ii) the unusual triphasic dependence of its ATPase activity on the concentration of F-actin, (iii) its Km for ATP, and (iv) its ability to translocate actin filaments. The Ala and Asn mutants had the same low actin-activated ATPase activity as unphosphorylated wild-type myosin IC. The Glu mutant, like the phosphorylated wild-type protein, was 16-fold more active than unphosphorylated wild type, and the Asp mutant was 8-fold more active. The wild-type and mutant proteins had the same Km for ATP. Unphosphorylated wild-type protein and the Ala and Asn mutants were unable to translocate actin filaments, whereas the Glu mutant translocated filaments at the same velocity, and the Asp mutant at 50% the velocity, as phosphorylated wild-type proteins. These results demonstrate that an acidic amino acid can supply the negative charge in the surface loop required for the actin-dependent activities of Acanthamoeba myosin IC in vitro and indicate that the length of the side chain that delivers this charge is important.     

Etiological and clinical characteristics of infectious optic neuritis

Infection by the tapeworm Echinococcus granulosus in the intermediate host results in the development of a hydatid cyst which contains the protoscoleces within a fluid-filled cavity enclosed by the bilayered cyst membrane. N-glycans were enzymatically released from crude extracts of homogenates of hydatid cyst membranes and protoscoleces and their structures were defined by high sensitivity fast atom bombardment mass spectrometry in conjunction with sequential exoglycosidase digestions. The major N-glycans from the cyst membrane were found to be non-charged structures having complex-type antennae and core fucosylation. The antennae are either truncated at the first N-acetylglucosamine or are extended with beta-galactose to form N-acetyllactosamine (lacNAc). A significant proportion of the lacNAc backbones are capped by alpha-galactose. The resulting Gal alpha-Gal beta-terminal structures may account for the earlier observation that antibodies against the blood group P1 epitope recognise components of hydatid cyst extracts. The complex-type N-glycans identified in the protoscoleces extracts were the same as the neutral structures found in the cyst membrane but a small proportion of high mannose structures and truncated di- and trimannosyl core structures were also identified. Sialylated N-glycans were identified as minor constituents of the cyst membrane preparation but were not observed in protoscoleces extracts. Whether the sialylated glycans are host derived or endogenously synthesized by the parasite remains to be established. This is the first reported structural analysis of N-glycans from cestodes and provides new insights into protein glycosylation in helminths.     

Removal and reinsertion of cemented femoral components during acetabular revision

The Mayo block is an extremely efficacious regional anesthetic technique used to provide anesthesia of the forefoot. Patients requiring surgical correction of hallux deformity, bunionectomy, and first metatarsal surgery may benefit from this technique. The Mayo block is a field block that anesthetizes the specific nerves of the forefoot that innervate the surgical field. This technique requires less local anesthesia than that required by direct local anesthetic infiltration and does not distort the surgical tissue planes. The Mayo block is effective. This technique has been used at one military hospital on more than 275 patients. The failure rate of the block is less than 1%. Learning this technique adds to the anesthetist's armamentarium of regional anesthesia, aids in rapid case turnover, and avoids the risks associated with major conduction and general anesthesia.     

Estimates of food and macronutrient intake in a random sample of Northern Ireland adolescents

Estimates of food consumption and macronutrient intake were obtained from a randomly selected population sample (2%) of 1015 adolescents aged 12 and 15 years in Northern Ireland during the 1990/1991 school year. Dietary intake was assessed by diet history with photographic album to estimate portion size. Reported median energy intakes were 11.0 and 13.1 MJ/d for boys aged 12 and 15 years respectively and 9.2 and 9.1 MJ/d for girls of these ages. Protein, carbohydrate and total sugars intakes as a percentage of total energy varied little between the age and sex groups and were approximately 11, 49 and 20% respectively of daily total energy intakes. Median dietary fibre intakes were approximately 20 and 24 g/d for boys aged 12 and 15 years respectively and 18 and 19 g/d for girls of these ages. Major food sources of energy (as a percentage of total energy intakes) were bread and cereals (15-18%), cakes and biscuits (12-14%), chips and crisps (13-14%), dairy products (9-11%), meat and meat products (9-11%) and confectionery (9%). Fruit and vegetable intakes were low at about 2.5% and 1.5% respectively of total energy intakes. Median fat intakes were high at 39% of total daily energy intakes. Major food sources of fat as a percentage of total fat intakes were from the food groupings: chips and crisps (16-19%), meat and meat products (14-17%), fats and oils (14-16%), cakes and biscuits (13-16%) and dairy products (12-15%). Median intakes of saturated fatty acids were also high at approximately 15% of daily total energy intake while intakes of monounsaturated fatty acids averaged 12% of daily total energy intake. Median polyunsaturated fatty acid (PUFA) intakes were low, comprising 5.2 and 5.5% of daily total energy intake for boys aged 12 and 15 years respectively and were lower than the PUFA intakes (5.9 and 6.3% of daily total energy intake) for girls of these ages. About 1.3% for boys and 1.4% for girls of daily total energy intake was in the form of n-3 PUFA. Ca and Mg intakes were adequate for both sexes. Based on these results, some concern about the dietary habits and related health consequences in Northern Ireland adolescents appears justified.     

Surgical procedure for modifying the duodenum in cattle to measure bile flow and the diurnal variation in biliary manganese, iron, copper and zinc excretion

A surgical procedure is described for modifying the duodenum of cattle so that bile can be sampled and its rate of flow measured for long periods. In 12 steers, aged three months to three years and weighing between 50 and 650 kg, bile flow ranged from 2 to 12 ml per minute, the rate of flow increasing with bodyweight. The rate of flow expressed as ml per minute per 100 kg bodyweight decreased as bodyweight increased, the regression equation being in (ml per minute per 10 kg) = 1.65-0.0022 x where x = bodyweight (kg), r = 0.871. The mean concentrations of copper, iron, manganese and zinc in bile were 8.2, 6.2, 17.1 and 3.3 mumol per litre respectively. The concentration of iron was the least variable between the steers. The average total cholate concentration was 100 mmol per litre and total solids ranged from 5.4 to 7.2 per cent. Diurnal patterns in bile flow and trace element excretion were measured in four adult steers during a period of 38.5 hours. Although the rate of excretion of iron, zinc and copper and bile flow varied throughout the period, changes could not be associated with feeding or time of day. The concentration of manganese in bile and its excretion rate varied in a reproducible manner which may be related to feeding activity. The mean output of the four trace elements in bile from the four steers during 24 hours was, copper 37.7 mumol, iron 68.0 mumol, manganese 80.3 mumol and zinc 59.6 mumol.