The National Survey of Local Anaesthesia for Ocular Surgery. II. Safety profiles of local anaesthesia techniques

PURPOSE

To describe the adverse events associated with local anaesthesia (LA) for intraocular surgery.

METHODS

An observational study of practice of LA in the whole of the United Kingdom was conducted over 3 months in late 1996. Staff in all ophthalmology theatres in the National Health Service were invited to report every LA given for the purpose of intraocular surgery during the first week, and thereafter to report adverse events only.

RESULTS

During the first week, the reported incidence of all adverse events within the orbit was 2.7%, and for 'systemic' adverse events it was 0.9%. Serious adverse events were reported in association with all LA techniques. In 3 months, 18 events were described as 'life-threatening' by respondents, and further patients were reported to have had epileptic fits or were transferred directly from the operating theatre to an intensive care unit. The voluntary nature of the survey introduces some bias from under-reporting, making the incidence of these severe events difficult to assess. Reported incidence of severe 'systemic' adverse events was similar for all LA techniques.

CONCLUSIONS

Serious adverse events were reported in association with with all LA techniques. This implies that we should be prepared for such events in all patients who have intraocular surgery.

The National Survey of Local Anaesthesia for Ocular Surgery. I. Survey methodology and current practice

PURPOSE

To describe the current usage of the various techniques of local anaesthesia (LA) in the United Kingdom, and safety precautions taken.

METHODS

An observational study of practice of LA in the whole of the United Kingdom was carried out over 3 months in late 1996. Staff in all ophthalmology theatres in the National Health Service were invited to report every LA given for the purpose of intraocular surgery during the first week, and thereafter to report adverse events only.

RESULTS

Participation during the first week was calculated to be 72.8% overall. Anaesthesia techniques for intraocular surgery were: 70% LA alone, 5.8% LA with sedation and 24.2% general anaesthesia. LA techniques were: 65.6% peribulbar, 16.9% retrobulbar, 6.7% sub-Tenon's, 4.4% subconjunctival, 2.9% topical and 2.3% combinations. Of patients who were given LA, 96% were monitored, 84% had an anaesthetist available in theatres in case of a problem and intravenous access was established in 60%.

CONCLUSION

Local anaesthesia is frequently used for intraocular surgery in the United Kingdom. A variety of techniques are used, and safety precautions are taken in most cases.

The size and form of the medulla of human scalp hair is regulated by the hair cycle and cross-sectional size of the hair shaft

Hairs were sampled from long-haired Caucasian females, and cross-sectional measurements were performed using a rotating profile method at fixed humidity (100%). The effect of the hair cycle on medullation was investigated by examining medulla size and form along the lengths of anagen and telogen terminal hairs and also from a composite model of the entire medulla, as produced from a full cycle's growth, by amalgamating the results from the anagen and telogen hairs. The effect of hair shaft cross-sectional size on medullation has been investigated by controlling any effect of the hair cycle on terminal hairs and by use of the maximal medulla size in short, fine (vellous) hairs from the same subjects. All terminal hairs were medullated for the majority of their lengths. The presence and size of the medulla, in terminal hairs, was profoundly affected by the hair cycle. It was largest early in anagen, where the medulla minor axis, major axis and cross-sectional area represented about 26%, 23% and 7% of the corresponding whole hair shaft parameters (at 100% humidity). The medulla was virtually absent towards the end of anagen. The shape of the medulla cross-section was less elliptical than that of the whole hair shaft and was close to circular. There was no significant change in medulla shape through anagen. The form of the medulla was also affected by the hair cycle; approximately, it was continuous for the first 50% of anagen, discontinuous for the next 25% and virtually absent or absent for the final 25%. The maximal size of the medulla, as occurred in early anagen, was markedly associated with the cross-sectional size of the whole hair shaft, both within terminal hairs and between all scalp hairs. The medulla was large in terminal hairs and small or absent in very small hairs. The proportion of the whole hair shaft occupied by the medulla increased with increase in hair size and reached a maximum in terminal hairs, in which the medulla minor axis represented about 30% of the whole hair shaft minor axis. Furthermore, this proportion was constant in the terminal hairs and was not related to whole hair shaft size. Such maximal proportional medullation might represent a defining feature of terminal hairs. Variation in size of the medulla is not the cause of the previously reported cycle-dependent change in cross-sectional size of the whole hair shaft of terminal hairs.

A glucan synthase FKS1 homolog in cryptococcus neoformans is single copy and encodes an essential function

Cryptococcal meningitis is a fungal infection, caused by Cryptococcus neoformans, which is prevalent in immunocompromised patient populations. Treatment failures of this disease are emerging in the clinic, usually associated with long-term treatment with existing antifungal agents. The fungal cell wall is an attractive target for drug therapy because the syntheses of cell wall glucan and chitin are processes that are absent in mammalian cells. Echinocandins comprise a class of lipopeptide compounds known to inhibit 1,3-beta-glucan synthesis, and at least two compounds belonging to this class are currently in clinical trials as therapy for life-threatening fungal infections. Studies of Saccharomyces cerevisiae and Candida albicans mutants identify the membrane-spanning subunit of glucan synthase, encoded by the FKS genes, as the molecular target of echinocandins. In vitro, the echinocandins show potent antifungal activity against Candida and Aspergillus species but are much less potent against C. neoformans. In order to examine why C. neoformans cells are less susceptible to echinocandin treatment, we have cloned a homolog of S. cerevisiae FKS1 from C. neoformans. We have developed a generalized method to evaluate the essentiality of genes in Cryptococcus and applied it to the FKS1 gene. The method relies on homologous integrative transformation with a plasmid that can integrate in two orientations, only one of which will disrupt the target gene function. The results of this analysis suggest that the C. neoformans FKS1 gene is essential for viability. The C. neoformans FKS1 sequence is closely related to the FKS1 sequences from other fungal species and appears to be single copy in C. neoformans. Furthermore, amino acid residues known to be critical for echinocandin susceptibility in Saccharomyces are conserved in the C. neoformans FKS1 sequence.

The therapy of amblyopia: an analysis comparing the results of amblyopia therapy utilizing two pooled data sets

CONTEXT

We previously presented the results of an original pooled data set of 961 amblyopic patients who underwent patching therapy for amblyopia from 1965 to 1994 (study group 1). Three types of amblyopia were considered: anisometropic, anisometropic-strabismic, and strabismic. Analysis of this group's success was related to the age at which therapy was initiated, the type of amblyopia, and the depth of visual loss before treatment was begun. The purpose of the current study is to test the validity of these findings on a second group of 961 amblyopes employing the data set used by Woodruff and associates in their publications (study group 2). These 2 data sets, after adjustment to conform to the definitions of age, amblyopia, anisometropia, and similar items utilized in common between the 2 study groups, will be compared for the risk factors predictive of successful occlusion therapy.

OUTCOME

As in the previous study, the success of occlusion therapy is defined as a visual acuity of 20/40 or better at the end of treatment.

RESULTS

Success by the 20/40 criteria was achieved in 73.7% in study group 1 and in 59.9% in study group 2. By category, the rate of success in study group 1 was 77.2% in strabismic amblyopia, 67.2% in anisometropic-strabismic amblyopia, and 66.0% in anisometropic amblyopia. In study group 2, success was 61.2% in strabismic amblyopia, 51.2% in anisometropic-strabismic amblyopia, and 63.0% in anisometropic amblyopia. Study group 1 univariate analysis related success in each group to the age at which therapy was initiated, the type of amblyopia, and the depth of visual loss before treatment in each group. In study group 2, univariate analysis related success of occlusion therapy to age and the depth of visual loss before treatment. Type of amblyopia was not related to outcome success in this group. When the 2 data sets were pooled, the risk factors for success were age and depth of visual loss at onset of treatment.

CONCLUSIONS

Factors that appeared closely related to a successful outcome of patching therapy were patient age and depth of visual loss before treatment. These conclusions further support the value of early detection and screening for amblyopia, its prevention, where possible, and its adequate and vigorous treatment when it is detected and diagnosed.

The murine Hoxb1 3' RAIDR5 enhancer contains multiple regulatory elements

Homeobox genes play key roles in specifying body part identity during vertebrate embryonic development. Retinoids are signaling molecules involved in the regulation of expression of homeobox genes. We have previously identified an retinoic acid (RA)-inducible enhancer (RAIDR5) located approximately 6.5 kb 3' of the coding region of the murine Hoxb1 gene. This 3' enhancer contains three sequences that are highly conserved in similar RA-inducible enhancers identified in the murine and human Hoxa1 genes and in the chicken Hoxb1 gene. One element, a DR5 RA response element, contributes to the RA inducibility of a Hoxb1 reporter gene construct in F9 cells. In this report, further analysis of the other two elements of the Hoxb1 3' enhancer is reported. The two other sequences, conserved element (CE) 1 and CE2, act as negative elements in cultured F9 cells; when either is mutated, an increase in the beta-galactosidase activity of a Hoxb1 reporter gene construct results. A single Hoxb1 CE2 DNA element:protein binding complex was detected in F9 stem cells, and experiments suggest that this is the same binding protein that recognizes the CE2 element of Hoxa1. In a variant F9 cell line in which both allelic copies of the RA receptor gamma (RARgamma) gene are disrupted, the CE2 binding complex is absent, and this absence correlates with the inability of the CE2 element to function as a repressor of Hoxb1 reporter gene expression in these cells. A single Hoxb1 CE1 binding complex is also detected by gel shift assays in nuclear extracts prepared from both stem and RA-treated F9 cells. This complex contains an Mr approximately 200,000 protein as shown by UV cross-linking. Although the sequences of the CE1 elements of Hoxb1 and Hoxa1 are highly conserved, they differ by two nucleotides. Gel shift analysis shows that either of these nucleotide changes prevents binding of F9 cell protein extracts. When gel shift assays were performed using nuclear extracts prepared from mouse embryos at a time when Hoxb1 mRNA is expressed, i.e., day 9.0, CE1 and CE2 binding complexes identical in mobility to those detected in F9 cells were observed. This suggests roles for both the CE1 and CE2 elements in regulating Hoxb1 gene expression during development.

Randomised, prospective study comparing cemented and cementless total knee replacement: results of press-fit condylar total knee replacement at five years

Early implants for total knee replacement were fixed to bone with cement. No firm scientific reason has been given for the introduction of cementless knee replacement and the long-term survivorship of such implants has not shown any advantage over cemented forms. In a randomised, prospective study we have compared cemented and uncemented total knee replacement and report the results of 139 prostheses at five years. Outcome was assessed both clinically by independent examination using the Nottingham knee score and radiologically using the Knee Society scoring system. Independent statistical analysis of the data showed no significant difference between cemented and cementless fixation for pain, mobility or movement. There was no difference in the radiological alignment at five years, but there was a notable disparity in the radiolucent line score. With cemented fixation there was a significantly greater number of radiolucent lines on anteroposterior radiographs of the tibia and lateral radiographs of the femur. At five years, our clinical results would not support the use of the more expensive cementless fixation whereas the radiological results are of unknown significance. Longer follow-up will determine any changes in the results and conclusions.

Successful isolation of a rat chromosome 1 blood pressure quantitative trait locus in reciprocal congenic strains

Linkage analyses in experimental crosses of hypertensive and normotensive rats have strongly suggested the presence of a quantitative trait locus (QTL) influencing blood pressure on rat chromosome 1, at or near the Sa gene. To confirm the presence of such a locus and move toward identification of the causative gene, we have developed, through targeted breeding over 10 generations using an Sa gene polymorphism to select breeders at each generation, 2 congenic strains, 1 containing a segment of spontaneously hypertensive rat (SHR) chromosome 1 in a Wistar-Kyoto rat (WKY) genetic background (WKY.SHR-Sa), and the other a segment of WKY chromosome 1 in an SHR background (SHR.WKY-Sa). WKY.SHR-Sa contains at least approximately 26 cM of SHR chromosome 1, between markers mD7mit206 and D1Mit2 (and including the SHR allele of the Sa gene), and SHR.WKY-Sa carries at least approximately 15 cM of WKY chromosome 1, between mD7mit206 and D1Wox34 (and including the WKY allele of the Sa gene). Blood pressure of WKY.SHR-Sa rats measured at 16, 20, and 25 weeks of age was significantly higher than that of WKY, whereas blood pressure of SHR.WKY-Sa rats was significantly lower than that of SHR. At 25 weeks, the mean differences in systolic and diastolic blood pressure between WKY.SHR-Sa and WKY were +11.5 mm Hg (P=0.001) and +11.6 mm Hg mm Hg (P<0.001), respectively. The corresponding differences between SHR.WKy-Sa and SHR were -11.3 mm Hg (P=0.002) and -9.1 mm Hg (P=0.005), respectively. The differences represent about one fifth of the blood pressure difference between SHR and WKY. Renal Sa mRNA levels in the congenic strains reflected their Sa allele with a high level in WKY. SHR-Sa and a low level in SHR.WKY-Sa, consistent with previous data suggesting that the level of Sa expression is primarily determined by cis-acting elements in or near the Sa gene. Our results show that we have successfully isolated a major rat chromosome 1 blood pressure QTL located in the vicinity of the Sa gene in reciprocal congenic strains derived from SHR and WKY. The strains can now be used to further define the region containing the QTL and also to characterize intermediary mechanisms through which the QTL influences blood pressure. In addition, comparison of the regions introgressed in our congenic strains with the location of the peak LOD score for chromosome 1 blood pressure QTL in second filial generation progeny derived from our SHRxWKY cross suggests that there may be at least 1 further QTL influencing blood pressure on this rat chromosome.

An improved protocol for the preparation of yeast cells for transformation by electroporation

Pretreatment of yeast cells with lithium acetate (LiAc) and dithiothreitol (DTT) enhances the frequency of transformation by electroporation. The method shows improvements of 6-67-fold in wild-type strains derived from commonly used Saccharomyces cerevisiae genetic backgrounds. In addition, 15-300-fold improvement in transformation frequency was achieved with several mutant strains of S. cerevisiae that transformed poorly by conventional procedures. Both DTT and lithium acetate were necessary for maximal transformation frequencies. Pretreatment with lithium and DTT also resulted in an approximately 3-5-fold increase in the electroporation transformation frequency of the pathogenic fungus Candida albicans.

Rex-1, a gene encoding a transcription factor expressed in the early embryo, is regulated via Oct-3/4 and Oct-6 binding to an octamer site and a novel protein, Rox-1, binding to an adjacent site

The Rex-1 (Zfp-42) gene, which encodes an acidic zinc finger protein, is expressed at high levels in embryonic stem (ES) and F9 teratocarcinoma cells. Prior analysis identified an octamer motif in the Rex-1 promoter which is required for promoter activity in undifferentiated F9 cells and is involved in retinoic acid (RA)-associated reduction in expression. We show here that the Oct-3/4 transcription factor, but not Oct-1, can either activate or repress the Rex-1 promoter, depending on the cellular environment. Rex-1 repression is enhanced by E1A. The protein domain required for Oct-3/4 activation was mapped to amino acids 1 to 35, whereas the domain required for Oct-3/4 repression was mapped to amino acids 61 to 126, suggesting that the molecular mechanisms underlying transcriptional activation and repression differ. Like Oct-3/4, Oct-6 can also lower the expression of the Rex-1 promoter via the octamer site, and the amino-terminal portion of Oct-6 mediates this repression. In addition to the octamer motif, a novel positive regulatory element, located immediately 5' of the octamer motif, was identified in the Rex-1 promoter. Mutations in this element greatly reduce Rex-1 promoter activity in F9 cells. High levels of a binding protein(s), designated Rox-1, recognize this novel DNA element in F9 cells, and this binding activity is reduced following RA treatment. Taken together, these results indicate that the Rex-1 promoter is regulated by specific octamer family members in early embryonic cells and that a novel element also contributes to Rex-1 expression.

Inter-observer and intra-observer agreement in the interpretation of visual fields in glaucoma

Visual field changes are one of the main parameters used to monitor progression of glaucoma. This study assesses the degree of intra-observer and inter-observer agreement among nine observers in grading visual fields in glaucoma patients using a visual field system previously described by Jay. The results show a median inter-observer agreement of 61% (median kappa = 0.52) and a median intra-observer agreement of 72% (median kappa = 0.65). This system for grading fields in glaucoma has a high degree of intra-observer agreement, suggesting it is a useful system for longitudinal follow-up of patients by a single observer. The higher degree of disagreement between observers points to the need for careful pretraining of observers in clinical management and research where the results from visual field examinations are to be graded by more than one clinician.

An evolutionary conserved element is essential for somite and adjacent mesenchymal expression of the Hoxa1 gene

The murine Hoxa1 gene is a member of the vertebrate Hox complex and plays a role in defining the body plan during development. At day 8.0-9.0 post coitus, Hoxa1 transcripts are detected extensively throughout the embryo in the neural tube, adjacent mesenchyme, paraxial mesoderm, somites and gut epithelium; expression extends from the most caudal region of the embryo to the rhombomere 3/4 border. This spatiotemporal expression of Hoxa1 mRNA is critical for normal embryonic development. We have previously identified a 10 bp element, called CE2, which is located approximately 3 kilobases 3' of the Hoxa1 coding region in the RAIDR5 enhancer, and which binds to an approximately 170 kd protein in retinoic acid treated P19 embryonal carcinoma cells. CE2 elements were also identified 3' of the murine Hoxb1 gene, the chicken Hoxb1 gene and the human Hoxa1 gene. To examine the role of this CE2 element in regulating Hoxa1 expression in vivo, transgenic mice were generated which express a Hoxa1 beta-galactosidase reporter gene that contains a mutation in the CE2 element. Relative to transgenic mice bearing a wild type CE2 element, the mutant CE2 construct recapitulated rhombomeric, neural, and gut epithelium expression but failed to show beta-galactosidase expression in somites and adjacent mesenchymal tissue. Gel shift analysis showed that binding activity similar to that detected in extracts prepared from retinoic acid treated P19 cells was present in nuclear extracts prepared from day 9.0 embryos. However, an additional binding complex not detected in P19 cells was also observed. These results indicate that in transgenic animals, the evolutionary conserved CE2 element is a somite and adjacent mesenchymal enhancer of Hoxa1 expression.

Associations between lens features assessed in the Oxford Clinical Cataract Classification and Grading System

PURPOSE

To study the associations between eleven lens features graded according to the Oxford Clinical Cataract Classification and Grading System (OCCCGS).

METHOD

560 subjects taking part in the Melton Eye Study had their lenses graded according to the OCCCGS by one of two examiners. Associations between features were examined using log-linear models for categorised grades. Adjustment was made for age, sex and grader.

RESULTS

Within subjects, the two nuclear features, white nuclear scatter and brunescence, are closely related with one another, as are coronary flakes and focal-dots, but these two groupings are negatively associated. Cortical spoke, fibrefolds and waterclefts are all associated with one another and this group is positively associated with coronary flakes and focal-dots. Posterior subcapsular and anterior subcapsular opacity are associated with one another and with cortical spokes. A within-eye analysis gives similar results.

CONCLUSION

These associations may be important in defining cataract subtypes and in identifying minor features that indicate early cataract development.

LOCS III versus the Oxford Clinical Cataract Classification and Grading System for the assessment of nuclear, cortical and posterior subcapsular cataract

PURPOSE

To compare two methods of cataract grading for nuclear cataract, cortical cataract and posterior subcapsular cataract.

METHODS

The Melton Eye Study is an English community-based epidemiological study of the natural history of eye disease in people aged 55 to 74 years. The lenses of both eyes of 560 subjects were graded at the slit lamp using two cataract grading systems. The Oxford Clinical Cataract Classification and Grading System (OCCCGS) employs standard diagrams and Munsell colour samples for the grading of cortical, posterior subcapsular and nuclear cataract. The Lens Opacities Classification System III (LOCS III) uses photographic transparencies of the lens as standards. In both systems a decimalised score is assigned. We also graded the LOCS III standard images using the OCCCGS. Interobserver variation was calculated for both grading systems. Linear calibration lines are plotted for each type of lens opacity.

RESULTS

The relationship between LOCS III and OCCCGS for nuclear cataract and posterior subcapsular cataract is linear. The relationship for cortical cataract is linear once the LOCS III scores are squared. The intervals between the LOCS III images when ranked by the human eye using the OCCCGS are linear. Interobserver variation for both systems is good.

CONCLUSIONS

The linear calibration lines may be used to convert from one system to another and will be useful in comparing studies or performing meta-analysis. These results show that data from cataract studies using different clinical grading schemes can be compared.

Prevalence of lenticular abnormalities in a population-based study: Oxford Clinical Cataract Grading in the Melton Eye Study

PURPOSE

To describe the distribution of the 11 features assessed by the Oxford Clinical Cataract Classification and Grading System (OCCCGS) in a population-based study.

METHODS

The Melton Eye Study is an English community-based epidemiological study of the natural history of eye disease in people aged 55 to 74 years. Both lenses of 560 subjects were graded at the slit lamp using a decimalised version of the OCCCGS. Subject prevalences were estimated by logistic regression and the extent, when present, against normal errors regression.

RESULTS

White nuclear scatter (WNS), brunescence, cortical spoke (CS), anterior subcapsular opacity (ASC), fibre folds (FF), waterclefts (WC) and perinuclear retro-dots all increased with age (p < 0.05). Posterior subcapsular opacity (PSC), vacuoles, focal dots (FD) and coronary flakes (CF) did not significantly increase with age. Subject prevalences of the features and the mean Oxford scores when present were: WNS (1.33), brunescence (0.88), CS 36% (0.34), PSC 11% (0.52), ASC 2% (0.53), FF 18% (0.53), WC 17% (0.29), retro-dots 11% (1.15), vacuoles 59% (0.43), FD 98% (1.79) and CF 39% (1.24). Significantly more common in women were both coronary flakes (p < 0.001) and waterclefts (p < 0.05).

CONCLUSIONS

These are the first data on the distribution of these minor lesions in a population-based study. Coronary flakes and waterclefts are more common in women.

Seven year follow-up of age-related maculopathy in an elderly British population

Despite age-related macular degeneration (AMD) being the commonest cause of blindness amongst the elderly in Western society, the incidence of new lesions is poorly documented and the natural history of existing disease remains ill understood.

PURPOSE

To document in an elderly population the incidence of new AMD lesions and the progression of pre-existing AMD over time.

METHOD

Baseline ophthalmic examinations were performed on a geographically defined random population sample of elderly people in 1982-4, and retinal photographs taken. The present study re-examined and re-photographed survivors after approximately 7 years using the same fundus camera. Photographs were randomly encoded, and independently graded for AMD features by two masked observers using the Wisconsin AMD grading system. Disagreements were resolved by review to reach a consensus.

RESULTS

Eighty-two of the 88 participating survivors had photographs of gradable quality on both occasions in at least one eye. Mean age at follow-up was 87 years (range 84-97 years) and 70.7% of subjects were female. Paired photographs were available on 158 eyes, and showed important differences in drusen type, drusen area and characteristics of the retinal pigment epithelium (RPE) between initial and subsequent examinations. The 7 year incidence (and regression) of lesions was: drusen 30.6% (20.0%), RPE degeneration 54.5% (8.8%), increased pigment 11.6% (64.7%), subretinal haemorrhage 1.3%, subretinal scar/fibrin 1.3% and geographic study 1.3%.

CONCLUSION

These unique population-based results provide new insight into the natural history of AMD in an elderly population.

Prevalence of age-related maculopathy at two points in time in an elderly British population

As the demography of Western society changes, the population prevalence of diseases such as age-related macular degeneration (AMD) is expected to rise. Despite this, there remains a paucity of quality data concerning the population prevalence of AMD, the commonest cause of blindness in the elderly.

PURPOSE

To report the prevalence of AMD at two points in time in an elderly population.

METHOD

A geographically defined random population sample of elderly people was defined in 1980, and studied in 1982-4. In 1990, a cohort of survivors was identified. Participants underwent full ophthalmic examination with fundus photography using the same camera on each occasion. Photographs were randomly encoded and graded by two independent masked observers using the Wisconsin Age-related Maculopathy Grading System. Disagreements were resolved by consensus.

RESULTS

Eighty-eight survivors participated in the follow-up examinations. Of these, 82 subjects had gradable retinal photographs for both examination points in at least one eye. There were 158 pairs of images (initial and subsequent) available for analysis. The mean age was 80 years (range 77-90 years) at the initial examination, and 87 years (range 84-97 years) at the subsequent examination; 70.7% of subjects were female. Prevalence rates for the initial examination were: drusen 72.8%, drusen confluence 37.3%, degeneration of the retinal pigment epithelium (RPE) 51.3%, increased pigment 22.2%, exudative AMD 1.9% and geographic atrophy 1.9%. Rates at second examination were: drusen 62.7% drusen confluence 41.8%, RPE degeneration 72.8%, increased pigment 16.5%, exudative AMD 3.8% and geographic atrophy 3.2%.

CONCLUSION

This 'double' prevalence study provides detailed data on AMD lesions at two points in time in a population-based group of elderly people.

Mortality and fatal pulmonary embolism after primary total hip replacement. Results from a regional hip register

We calculated the rates for perioperative mortality and fatal pulmonary embolism (PE) after primary total hip replacement in a single UK health region, using a regional arthroplasty register and the tracing service of the Office of National Statistics. During 1990, there were 2111 consecutive primary replacements in 2090 separate procedures. Within 42 days of operation a total of 19 patients had died (0.91%, 95% CI 0.55 to 1.42). Postmortem examination showed that four deaths (0.19%, 95% CI 0.05 to 0.49) were definitely due to PE. The overall perioperative mortality and fatal PE rates are low and in our study did not appear to be altered by the use of chemical thromboprophylaxis (perioperative mortality rate: one-tailed Fisher's exact test, p = 0.39; fatal PE rate: one-tailed Fisher's exact test, p = 0.56). The routine use of chemical thromboprophylaxis for primary THR is still controversial. The issue should be addressed by an appropriate randomised, prospective study using overall mortality and fatal PE rate as the main outcome measures, but the feasibility of such a study is questioned.

A pharmacogenetic approach to blood pressure in Lyon hypertensive rats. A chromosome 2 locus influences the response to a calcium antagonist

In a backcross population (n = 281) derived from a cross of the Lyon hypertensive rat with Lyon normotensive rat, we investigated whether genetic factors influence the acute cardiovascular responses to pharmacological modulation of the renin-angiotensin system, the sympathetic nervous system, and the voltage-sensitive L-type calcium channels. Using microsatellite markers, a quantitative trait locus was identified and mapped on rat chromosome 2 that specifically influences the systolic (peak LOD score 4.4) and diastolic (peak LOD score 4.1) blood pressure responses to administration of a dihydropyridine calcium antagonist, PY108-068. The locus accounted for 10.3 and 10.4% of the total variances in the systolic and diastolic responses to PY108-068, respectively. In marked contrast, the locus had no effect on either basal blood pressure or on the responses to acute administration of a ganglionic blocking agent, trimetaphan, or of an angiotensin II subtype 1 receptor antagonist, losartan. These findings provide strong direct support for the paradigm that genetic factors may influence the response to antihypertensive drugs and suggest that the heterogeneity seen in the responses to different antihypertensive agents in human essential hypertension may have a significant genetic determination.

Modeling the impact of HIV on the spread of tuberculosis in the United States

Tuberculosis (TB) was thought to be safely in decline in the United States in the mid-1980s because the number of cases had dropped by 74% between 1953 and 1985. An increase in TB cases was reported, however, in 1986, and an upward trend in TB incidence has continued. The turnaround in TB is well correlated with the rise of the HIV (human immunodeficiency virus) epidemic. The purpose of this work is to investigate, through the use of mathematical models, the magnitude and duration of the effect that the HIV epidemic may have on TB. Models are developed which reflect the transmission dynamics of both TB and HIV, and the relative merits of these models are discussed. The models are then linked together to form a model for the combined spread of both diseases. A numerical study is performed to investigate the influence of certain key parameters. The effect that HIV will have on the general population is found to be dependent on the contact structure between the general population and the HIV risk groups, as well as a possible shift in the dynamics associated with TB transmission.

Regulation of protein turnover by glutamine in heat-shocked skeletal myotubes

Skeletal muscle accounts for approximately one-half of the protein pool in the whole body. Regulation of protein turnover in skeletal muscle is critical to protein homeostasis in the whole body. Glutamine has been suggested to exert an anabolic effect on protein turnover in skeletal muscle. In the present work, we characterized the effect of glutamine on the rates of protein synthesis and degradation in cultured rat skeletal myotubes under both normal and heat-stress conditions. We found that glutamine has a stimulatory effect on the rate of protein synthesis in stressed myotubes (21%, P < 0.05) but not in normal-cultured myotubes. Glutamine shows a differential effect on the rate of degradation of short-lived and long-lived proteins. In both normal-cultured and stressed myotubes, the half-life of short-lived proteins was not altered while the half-life of long-lived proteins increased with increasing concentrations of glutamine in a concentration-dependent manner. In normal-cultured myotubes, when glutamine concentration increased from 0 to 15 mM, the half-life of long-lived proteins increased 35% (P < 0.001) while in stressed myotubes, it increased 27% (P < 0.001). We also found that glutamine can significantly (P < 0.001) increase the levels of heat-shock protein 70 (HSP70) in stressed myotubes, indicating that HSP 70 may participate in the mechanism underlying the effect of glutamine on protein turnover. We conclude that in cultured skeletal myotubes the stimulatory effect of glutamine on the rate of protein synthesis is condition-dependent, and that the inhibitory effect of glutamine on the rate of protein degradation occurs only on long-lived proteins.