A Comprehensive Review of Lemborexant to Treat Insomnia

Purpose of Review

This is a comprehensive review of the literature regarding Lemborexant for the treatment of insomnia. It covers the background and management of insomnia and then reviews the body of existing evidence evaluating the use of Lemborexant for this purpose.

Recent Findings

Insomnia leads to significant decreased in quality of life and economic burden due to decreased workplace performance and increased health care costs. Insomnia manifests as a single common pathway of hyperarousal due to a highly complex network of interactions between activation of the sympathetic system and the endocrine system. Lemborexant is a dual orexin 1/2 antagonist that blocks cortical arousal and promotes sleep state transition. Lemborexant was approved by the FDA in 2019 for use in insomnia. It belongs to a class of orexin neuropeptide inhibitors that is growing in popular clinical application.

Summary

Insomnia is a crippling disorder of the sleep wake cycle that drives significant morbidity and mortality in the United States. It carries a high societal and economic toll due to direct and indirect effects to the healthcare system. Lemborexant is a new addition to the orexin antagonist class of drugs that already includes Almorexant and Suvorexant that has superior pharmacokinetic properties. While Lemborexant does have a mild side effect profile, its clinical safety and efficacy make it a promising insomnia drug of the future.

A Comprehensive Review of Solriamfetol to Treat Excessive Daytime Sleepiness

Purpose of Review

This is a comprehensive review of the literature regarding the use of Solriamfetol for excessive daytime sleepiness. It covers the background and current therapeutic approaches to treating excessive daytime sleepiness, the management of common comorbidities, and the existing evidence investigating the use of Solriamfetol for this purpose.

Recent Findings

Excessive daytime sleepiness leads to worse quality of life, a medical sequela and significant economic cost. There are multiple phenotypes of excessive daytime sleepiness depending on the comorbidity making treatment challenging. Due to the complexity of etiology there is not a cure for this ailment. Solriamfetol is a norepinephrine/dopamine dual reuptake antagonist that can be used to manage daytime sleepiness. Solriamfetol was first approved by the FDA in 2018 for use in excessive daytime sleepiness associated with obstructive sleep apnea and narcolepsy. Ongoing literature has proved this drug to be a safe and effective alternative pharmacotherapy.

Summary

Recent epidemiological data estimate up to one-third of the general adult population suffers from excessive daytime sleepiness. There is no cure to daytime somnolence and current pharmacotherapeutic regimens have worrisome side effect profiles. Solriamfetol is a new class of drug that offers a safe and effective alternative option for clinical providers treating excessive daytime sleepiness.

Microsurgical breast reconstruction and primary hypercoagulable disorders

BACKGROUND

Primary hypercoagulable disorders pose a significant challenge to microsurgeons and have traditionally been regarded as a relative contraindication to free tissue transfer. Since free flaps offer numerous advantages in breast reconstruction, there is an effort to expand the population to whom these operations can be safely offered. The purpose of this study is to describe our chemoprophylaxis regimen in cases of primary hypercoagulability, as well as to compare flap outcomes and complications between women with and without hypercoagulability.

PATIENTS AND METHODS

A single institution retrospective review identified 15 patients (25 flaps) with known primary hypercoagulability who underwent microsurgical breast reconstruction from 2010 through 2020. There were 785 patients (1268 flaps) without primary hypercoagulability who underwent microsurgical breast reconstruction, including 40 patients (73 flaps) with a history of venous thromboembolism (VTE), evaluated for comparison. Patient characteristics, thromboprophylaxis regimen, and surgical outcomes were collected. In carrying out this cohort study, we have adhered to Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) guidelines.

RESULTS

Fifteen patients with primary hypercoagulability were identified, including heterozygous factor V Leiden mutation (n = 12), protein S deficiency (n = 1), prothrombin mutation (n = 1), and primary antiphospholipid syndrome (n = 1). Thirteen of these (87%) were discharged with an extended LMWH course. There was no postoperative VTE or mortality in this cohort, and no significant difference in hematoma or transfusion compared with the control group (p = .31, p = .87, respectively). The flap loss rate was 4% in the hypercoagulable group compared with 0.92% in the control group (p = .15). The salvage for arterial or venous compromise in the hypercoagulable group was poor (0% vs. 52%, p = .3).

CONCLUSION

Microsurgical breast reconstruction in women with primary hypercoagulability disorders is feasible with acceptable risk of flap loss but poor salvage potential. Postoperative thromboprophylaxis with extended prophylactic LMWH in this population appears to be a safe regimen.

Self-reported concussion history among midwestern skiers and snowboarders

Aim

To assess the rate of self-reported concussion in midwestern skiers and snowboarders.

Patients

Recreational skiers and snowboarders between the ages of 14 and 69 years during a single winter ski season (2020-2021) at a ski area in Wisconsin, USA.

Methods

Survey study.

Results

Among this survey population (n = 161), 9.32 and 19.25% reported one or more diagnosed concussion and suspected concussion respectively as a result of a skiing- or snowboarding-related incident. Skiers and snowboarders that self-identified as advanced, those who utilized terrain park features, and those that participated in freestyle competition had significantly higher self-reported rates of concussion.

Conclusion

Self-reported concussion history indicates a concussion prevalence that is higher than expected based on previous studies. Participants reported significantly more suspected concussions than diagnosed concussions, indicating a possible issue with underreporting in this population.

The longitudinal relationship between child emotional disorder and parental mental health in the British Child and Adolescent Mental Health surveys 1999 and 2004

BACKGROUND

Research suggests parental psychopathology has an adverse effect on child mental health. However, due to the interactional nature of parent-child relationships and with a high rate of emotional disorders reported in school-age children, it is important to know whether the effect is reciprocal.

METHODS

We explored the longitudinal relationship between child and parent mental health in the British Child and Adolescent Mental Health Surveys (N=7,100 child-parent dyads) and their three-year follow-ups. The Development and Well-Being Assessment with DSM-IV diagnostic criteria was used to measure child psychiatric diagnoses, while parental mental health was assessed using the General Health Questionnaire. Multivariable logistic regression was used to explore the longitudinal association between child emotional disorder and parent mental health.

RESULTS

Parents of children who had an emotional disorder at baseline were more likely to have poor mental health three years later compared with parents whose children had no psychiatric diagnosis (33.3% versus 16.7%; crude odds ratio=2.52; adjusted odds ratio=2.19, 95% CI=1.58 to 3.05, p<0.001). Children of parents with poor mental health at baseline were more likely to develop an emotional disorder three years later compared with children whose parents had good mental health (5.2% versus 2.5%; crude odds ratio=2.08; adjusted odds ratio=1.63, 95% CI=1.18 to 2.25, p=0.003).

LIMITATIONS

The findings of this research are limited by the survey data collected, the measures used and survey dropout.

CONCLUSIONS

We detected a bi-directional relationship between child and parent mental health, suggesting that effective intervention for one individual may benefit other family members.

Seropositivity of HBsAg, anti HCV and anti HIV among blood donors: a comparative study on three years of 5 years interval

Blood safety comprises the provision of safe, adequate and quality blood components to the needy patients. A total of 6,179 donation were reviewed with 2377, 1561 and 2241 donations occurring in June to July in 1993, 1998 and 2003 respectively. Majority of the donors were males. 94.38% donors were in the age group of 18 - 45 years. The seropositivity of HBV infection declined over the three years but HCV and HIV infections showed an increase in 2003 following an initial decrease in 1998.

A novel mutation in the connexin 46 gene (GJA3) causes autosomal dominant zonular pulverulent cataract in a Hispanic family

PURPOSE

A five-generation Hispanic pedigree with autosomal dominant zonular pulverulent cataract was studied to identify the causative mutation in connexin 46 (Cx46), a gap junction protein responsible for maintaining lens homeostasis.

METHODS

Twenty-six individuals from the family were comprehensively clinically examined. DNA was extracted from their peripheral blood samples. The DNA was used for automated genotyping with fluorescently labeled microsatellite markers and for mutation detection by automated sequencing.

RESULTS

A novel D3Y missense mutation in GJA3 segregated with autosomal dominant (AD) zonular pulverulent cataract throughout the family. The mutation was absent in the unaffected individuals in the family and in 230 control chromosomes.

CONCLUSIONS

A novel mutation causing AD zonular pulverulent cataract has been identified in a Hispanic Central American family. This is the first report of a mutation in GJA3 causing autosomal dominant congenital cataract (ADCC) in this ethnic group. It is also the first reported cataract-causing mutation in the NH2-terminal region of the Cx46 protein.

Posterior polar cataract is the predominant consequence of a recurrent mutation in the PITX3 gene

BACKGROUND

The authors recently identified three large genetically unrelated families with an identical 17 base pair duplication mutation in exon 4 of the PITX3 gene. Here, they report the detailed clinical phenotype.

METHODS

Affected and unaffected individuals in the three families with autosomal dominant posterior polar cataract underwent full clinical examination and donated blood samples for DNA extraction and molecular genetic studies.

RESULTS

In all three families, an identical 17 base pair duplication mutation in PITX3 was identified which co-segregated with disease status in the family. All affected individuals had bilateral progressive posterior polar cataracts. In one family, posterior polar cataract was the only clinical abnormality but in the other two families, one of 10 affected individuals and four of 11 affected individuals also had anterior segment mesenchymal dysgenesis (ASMD).

CONCLUSION

Mutations in the PITX3 gene in humans result in posterior polar cataract and variable ASMD. The gene encodes a transcription factor which has a key role in lens and anterior segment development. The mechanism by which the mutant protein gives rise to such a regional pattern of lens opacity remains to be elucidated.

Characterization of the G91del CRYBA1/3-crystallin protein: a cause of human inherited cataract

Congenital cataract is a leading cause of visual disability in children. Inherited isolated (non-syndromic) cataract represents a significant proportion of cases and the identification of genes responsible for inherited cataract will lead to a better understanding of the mechanism of cataract formation at the molecular level both in congenital and age-related cataract. Crystallins are abundantly expressed in the developing human lens and represent excellent candidate genes for inherited cataract. A genome-wide search of a five-generation family with autosomal dominant lamellar cataract demonstrated linkage to the 17p12-q11 region. Screening of the CRYBA1/3 gene showed a 3 bp deletion, which resulted in a G91del mutation within the tyrosine corner, that co-segregated with disease and was not found in 96 normal controls. In order to understand the molecular basis of cataract formation, the mutant protein was expressed in vitro and its unfolding and refolding characteristics assessed using far-UV circular dichroism spectroscopy. Defective folding and a reduction in solubility were found. As the wild-type protein did not refold into the native conformation following unfolding, a corresponding CRYBB2 mutant was genetically engineered and its refolding characteristics analysed and compared with wild-type CRYBB2. Its biophysical properties support the hypothesis that removal of the glycine residue from the tyrosine corner impairs the folding and solubility of beta-crystallin proteins. This study represents the first comprehensive description of the biophysical consequences of a mutant beta-crystallin protein that is associated with human inherited cataract.

A clinical and molecular genetic study of a rare dominantly inherited syndrome (MRCS) comprising of microcornea, rod-cone dystrophy, cataract, and posterior staphyloma

AIM

To phenotype and genetically map the disease locus in a family presenting with autosomal dominant microcornea, rod-cone dystrophy, cataract, and posterior staphyloma.

METHODS

Six affected and three unaffected members of the pedigree were examined. All individuals provided a history and underwent a full clinical examination with A-scan and B-scan ultrasonography and electrophysiological testing where appropriate. PCR based microsatellite marker genotyping using a positional candidate gene approach was then performed on DNA samples extracted from venous blood provided by each subject.

RESULTS

The disorder is inherited as an autosomal dominant trait with variable expressivity and has a complex phenotype. Affected individuals had bilateral microcornea, pulverulent-like lens opacities, a rod-cone dystrophy and posterior staphyloma (MRCS). Using a positional candidate gene approach, the authors have evidence suggestive of linkage of this disorder to a region on 11q13 within the nanophthalmos 1 (NNO1) genetic interval. The small family size militates against achieving a LOD score of 3, but the haplotype data and the position of the putative MRCS locus within a known nanophthalmos locus are suggestive of linkage. A candidate gene within this region (ROM1) was screened and no mutations were found in affected members of the family.

CONCLUSION

This rare developmental disorder has some phenotypic similarities to nanophthalmos and possibly maps to a locus within the genetic interval encompassing the NNO1 locus. Screening of candidate genes within this region continues.

A locus for isolated cataract on human Xp

PURPOSE

To genetically map the gene causing isolated X linked cataract in a large European pedigree.

METHODS

Using the patient registers at Birmingham Women's Hospital, UK, we identified and examined 23 members of a four generation family with nuclear cataract. Four of six affected males also had complex congenital heart disease. Pedigree data were collated and leucocyte DNA extracted from venous blood. Linkage analysis by PCR based microsatellite marker genotyping was used to identify the disease locus and mutations within candidate genes screened by direct sequencing.

RESULTS

The disease locus was genetically refined to chromosome Xp22, within a 3 cM linkage interval flanked by markers DXS9902 and DXS999 (Zmax=3.64 at theta=0 for marker DXS8036).

CONCLUSIONS

This is the first report of a locus for isolated inherited cataract on the X chromosome. The disease interval lies within the Nance-Horan locus suggesting allelic heterogeneity. The apparent association with congenital cardiac anomalies suggests a possible new oculocardiac syndrome.

Alpha-B crystallin gene (CRYAB) mutation causes dominant congenital posterior polar cataract in humans

Congenital cataracts are an important cause of bilateral visual impairment in infants. In a four-generation family of English descent, we mapped dominant congenital posterior polar cataract to chromosome 11q22-q22.3. The maximum LOD score, 3.92 at recombination fraction 0, was obtained for marker D11S898, near the gene that encodes crystallin alpha-B protein (CRYAB). By sequencing the coding regions of CRYAB, we found in exon 3 a deletion mutation, 450delA, that is associated with cataract in this family. The mutation resulted in a frameshift in codon 150 and produced an aberrant protein consisting of 184 residues. This is the first report of a mutation, in this gene, resulting in isolated congenital cataract.

Visual outcome in patients with isolated autosomal dominant congenital cataract

OBJECTIVE

To determine the visual outcome and surgical complication rates of patients with isolated inherited congenital cataract.

DESIGN

Retrospective noncomparative case series.

PARTICIPANTS

Patients and their families were ascertained from the genetic eye clinic and outpatient databases of Moorfields Eye Hospital, London, and invited to participate in the study. Four hundred twenty-two individuals from 72 pedigrees with this form of autosomal dominant cataract underwent ophthalmologic assessment.

MAIN OUTCOME MEASURES

Visual acuity and surgical complications (glaucoma, retinal detachment, amblyopia).

RESULTS

In this study 49.4% of patients (46.8% of those operated) achieved a visual acuity (VA) of 20/40 or better, 35.9% (36.1% of those operated) a VA between 20/50 and 20/200, and 14.7% (17.1% of those operated) worse than 20/200. Opacities that were more diffuse or did not lie close to the visual axis were associated with a better prognosis for vision; 6.6% had glaucoma and 5.0% had retinal detachment develop.

CONCLUSIONS

Patients with isolated inherited congenital cataract have a better visual and surgical outcome than those with coexisting ocular and systemic abnormalities. The improved prognosis is related in part to the lack of other developmental abnormalities of the eye, and, because inherited cataracts are often partial at birth, surgery may be delayed to later infancy and childhood when there is a lower incidence of surgical complications and refractive correction is easier. Certain inherited phenotypes (lamellar, pulverulent, polymorphic, coralliform, and cortical) also seem to have a better prognosis, and this should be borne in mind when counseling these families. A large number of the patients in this study underwent surgery many years previously, when surgical outcomes were less favorable, and thus the results of this study establish only a minimum acuity dataset for the purposes of counseling.

Congenital progressive polymorphic cataract caused by a mutation in the major intrinsic protein of the lens, MIP (AQP0)

BACKGROUND

Congenital cataract, when inherited as an isolated abnormality, is phenotypically and genetically heterogeneous. Although there is no agreed nomenclature for the patterns of cataract observed, a recent study identified eight readily identifiable phenotypes.

METHODS

The Moorfields Eye Hospital genetic eye clinic database was used to identify a four generation family with isolated autosomal dominant congenital cataracts. All individuals (affected and unaffected) underwent a full ophthalmic assessment.

RESULTS

The results of the molecular linkage study identifying a missense mutation in the gene encoding the major intrinsic protein of the lens (MIP) have been published elsewhere. Affected individuals had bilateral discrete progressive punctate lens opacities limited to mid and peripheral lamellae with additional asymmetric polar opacification. One young female had predominantly cortical cataract and another had serpiginous nuclear opacities.

CONCLUSIONS

This phenotype has not been recorded in human families before and has been termed polymorphic. The pattern of opacification appears to reflect the distribution of MIP in the lens. Furthermore, this is the first clear evidence of allelic heterogeneity in this condition following the identification of a family with lamellar cataracts who have a different mutation within the MIP gene.

Functional impairment of lens aquaporin in two families with dominantly inherited cataracts

Opacities in the crystalline lens of eye appear with high frequency in the general population. Dominantly inherited cataracts with differing clinical features were found in two families carrying different point mutations in the gene encoding lens water channel protein AQP0 (major intrinsic protein, MIP). Families with E134G have a uni-lamellar cataract which is stable after birth, whereas families with T138R have multi-focal opacities which increase throughout life. To establish pathophysiological relevance of cataract formation, the Xenopus laevis oocyte expression system was employed to evaluate functional defects in the mutant proteins, E134G and T138R. Both substitutions cause loss of membrane water channel activity due to impaired trafficking of the mutant proteins to the oocyte plasma membrane. Although missense mutations in AQP1 and AQP2 proteins are known to result in recessive traits in vivo and in vitro, when E134G or T138R are co-expressed with wild-type AQP0 protein, the mutant proteins exhibit dominant negative behaviour. To our knowledge, these studies represent the first in vitro demonstration of functionally defective AQP0 protein from humans with congenital cataracts. Moreover, these observations predict that less severe defects in the AQP0 protein may contribute to lens opacity in patients with common, less fulminant forms of cataracts.

The genetics of childhood cataract

Human congenital cataract has a diverse aetiology. In the proportion of cases where the cause is genetic, the disease shows wide phenotypic and genetic heterogeneity. Over the past few years, much research has been devoted to mapping the genes that underlie the disorder. This has been helped by the extensive array of naturally occurring and genetically engineered mouse cataract models and the abundance of human candidate genes. Most progress to date has been in the identification of genetic mutations causing autosomal dominant congenital cataract where eight genes have been implicated in cataractogenesis. Overall there is good correlation between the genetic mutations so far identified and the resulting lens phenotype but it is clear that mutations at more that one locus may give rise to similar forms of cataract. The identification of genes causing inherited forms of cataract will improve our understanding of the mechanisms underlying cataractogenesis in childhood and provide further insights into normal lens development and physiology. Perhaps more importantly, it is likely that some of the genes causing early onset cataract will be implicated in age related cataract which remains the commonest cause of blindness in the world.

Missense mutations in MIP underlie autosomal dominant 'polymorphic' and lamellar cataracts linked to 12q

Human inherited cataract is both clinically diverse and genetically heterogeneous. Here we report the identification of the first mutations affecting the major intrinsic protein of the lens, MIP, encoded by the gene MIP on 12q14. MIP is a member of the aquaporin family of membrane-bound water channels. The mutations identified are predicted to disturb water flux across the lens cell membrane.

Comparative efficacy of gemifloxacin in experimental models of pyelonephritis and wound infection

Gemifloxacin (SB-265805) is a potent, novel fluoroquinolone with broad-spectrum antimicrobial activity. In this study, the efficacy of gemifloxacin was studied in experimental models of Gram-negative pyelonephritis (caused by Escherichia coli or Proteus mirabilis) and Gram-positive wound infection resulting from Streptococcus pyogenes, Staphylococcus epidermidis or Staphylococcus aureus. Gemifloxacin activity against these pathogens was compared with those of amoxycillin-clavulanate, ciprofloxacin, cefuroxime, azithromycin, trovafloxacin, grepafloxacin, levofloxacin and tosufloxacin. Oral treatment was initiated 1 h after infection and continued once or twice daily for 3 days. Around 17 h after the end of treatment, animals were killed and the infected kidneys or the skin around the wound site were excised for the enumeration of viable bacteria. In the pyelonephritis model (either microorganism), gemifloxacin reduced bacterial numbers significantly (P < 0.01) compared with no treatment. No comparator agent had a greater effect than gemifloxacin. Notably, grepafloxacin and azithromycin were significantly less effective (P < 0.01) than gemifloxacin against E. coli pyelonephritis, and amoxycillin-clavulanate, azithromycin and trovafloxacin were inferior (P < 0.01) against P. mirabilis infection. In the S. pyogenes wound infection model, gemifloxacin, amoxycillin-clavulanate, cefuroxime and azithromycin reduced bacterial numbers significantly compared with controls (P < 0.01). Results for the comparator quinolones were not significantly different from untreated controls (P > 0.05). Gemifloxacin was also effective against staphylococcal infection, as were grepafloxacin and levofloxacin, while ciprofloxacin, trovafloxacin and tosufloxacin were significantly less effective against these pathogens than gemifloxacin (P < 0.01). No comparator agent had greater activity than gemifloxacin against S. pyogenes or S. aureus infections. These data demonstrate the potential benefit of gemifloxacin in the treatment of Gram-negative urinary tract infection and Gram-positive skin and soft tissue infection.

Comparative in vivo activity of gemifloxacin in a rat model of respiratory tract infection

The in vivo efficacy of the novel quinolone gemifloxacin (SB-265805) was examined in a rat respiratory tract infection (RTI) model against four strains of Streptococcus pneumoniae and two strains of Haemophilus influenzae with varying susceptibilities to standard antimicrobial agents. Animals were infected intrabronchially to produce pneumonia and therapy with oral gemifloxacin, amoxycillin-clavulanate, ciprofloxacin, cefuroxime, azithromycin, trovafloxacin, grepafloxacin or levofloxacin was started 24 h after infection. The doses administered were chosen to approximate in the rat the serum or tissue concentrations measured in humans following therapeutic dosing. Therapy continued once- or twice-daily for 3 days, and approximately 17 h after the end of therapy the lungs were excised for bacterial enumeration. Following infection with strains of S. pneumoniae, gemifloxacin produced a 3-5 log reduction in bacterial numbers compared with untreated animals. Gemifloxacin was as effective as amoxycillin- clavulanate, and was as potent or more potent than all other comparators. Notably, the quinolone agents trovafloxacin, ciprofloxacin, grepafloxacin and levofloxacin were significantly less effective (P < 0.01) than gemifloxacin: these agents reduced bacterial numbers by < or =3 log compared with untreated animals. Gemifloxacin produced a marked response against H. influenzae infection, reducing bacterial numbers significantly (P < 0.01) compared with untreated controls. Gemifloxacin was significantly more potent than cefuroxime and azithromycin. None of the other comparator agents was more potent than gemifloxacin. The excellent efficacy seen in these experimental models of RTI with S. pneumoniae and H. influenzae confirms the in vitro activity of gemifloxacin against these organisms. This indicates that gemifloxacin may be of significant benefit in the treatment of RTI.

Clinical and genetic heterogeneity in autosomal dominant cataract

AIMS

To determine the different morphologies of autosomal dominant cataract (ADC), assess the intra- and interfamilial variation in cataract morphology, and undertake a genetic linkage study to identify loci for genes causing ADC and detect the underlying mutation.

METHODS

Patients were recruited from the ocular genetic database at Moorfields Eye Hospital. All individuals underwent an eye examination with particular attention to the lens including anterior segment photography where possible. Blood samples were taken for DNA extraction and genetic linkage analysis was carried out using polymorphic microsatellite markers.

RESULTS

292 individuals from 16 large pedigrees with ADC were examined, of whom 161 were found to be affected. The cataract phenotypes could all be described as one of the eight following morphologies-anterior polar, posterior polar, nuclear, lamellar, coralliform, blue dot (cerulean), cortical, and pulverulent. The phenotypes varied in severity but the morphology was consistent within each pedigree, except in those affected by the pulverulent cataract, which showed considerable intrafamilial variation. Positive linkage was obtained in five families; in two families linkage was demonstrated to new loci and in three families linkage was demonstrated to previously described loci. In one of the families the underlying mutation was isolated. Exclusion data were obtained on five families.

CONCLUSIONS

Although there is considerable clinical heterogeneity in ADC, the phenotype is usually consistent within families. There is extensive genetic heterogeneity and specific cataract phenotypes appear to be associated with mutations at more than one chromosome locus. In cases where the genetic mutation has been identified the molecular biology and clinical phenotype are closely associated.

Connexin 50 mutation in a family with congenital "zonular nuclear" pulverulent cataract of Pakistani origin

Inherited cataract is a clinically and genetically heterogeneous disease that most often presents as a congenital autosomal dominant trait. Here we report linkage of a three-generation family of Pakistani origin with autosomal dominant cataract "zonular nuclear" pulverulent type (CZNP) on chromosome 1q21.1. Genome wide-linkage analysis excluded all the known cataract loci except on chromosome 1q. Significantly positive 2-point lod score values (Z=3.01 at theta=0) were obtained for markers D1S305 and D1S2721, which are known to flank the gene for connexin 50 (Cx50) or gap junction protein alpha-8 (Gja8). Previously a mutation in this gene has been reported in a British family with zonular pulverulent cataract (CZP). Here we describe a second mutation (E48K) in connexin 50 that confirms the involvement of this gene in cataractogenesis.

Lens biology: development and human cataractogenesis

Cataract, or opacification of the lens of the eye, is the commonest cause of visual impairment world-wide. It is only treatable at present by surgical removal. Recent advances in our understanding of the genetics of human cataract, in particular the inherited congenital form, together with the development of an array of animal models have provided valuable new insights into normal vertebrate lens biology and the mechanisms that underlie cataract formation. In this article, we review the current state of research in these areas and discuss thinking regarding the relationship between the phenotypes observed and the underlying genotype in inherited cataract.

Connexin46 mutations in autosomal dominant congenital cataract

Loci for autosomal dominant "zonular pulverulent" cataract have been mapped to chromosomes 1q (CZP1) and 13q (CZP3). Here we report genetic refinement of the CZP3 locus and identify underlying mutations in the gene for gap-junction protein alpha-3 (GJA3), or connexin46 (Cx46). Linkage analysis gave a significantly positive two-point LOD score (Z) at marker D13S175 (maximum Z [Zmax]=>7.0; maximum recombination frequency [thetamax] =0). Haplotyping indicated that CZP3 probably lies in the genetic interval D13S1236-D13S175-D13S1316-cen-13pter, close to GJA3. Sequencing of a genomic clone isolated from the CZP3 candidate region identified an open reading frame coding for a protein of 435 amino acids (47,435 D) that shared approximately 88% homology with rat Cx46. Mutation analysis of GJA3 in two families with CZP3 detected distinct sequence changes that were not present in a panel of 105 normal, unrelated individuals. In family B, an A-->G transition resulted in an asparagine-to-serine substitution at codon 63 (N63S) and introduced a novel MwoI restriction site. In family E, insertion of a C at nucleotide 1137 (1137insC) introduced a novel BstXI site, causing a frameshift at codon 380. Restriction analysis confirmed that the novel MwoI and BstXI sites cosegregated with the disease in families B and E, respectively. This study identifies GJA3 as the sixth member of the connexin gene family to be implicated in human disease, and it highlights the physiological importance of gap-junction communication in the development of a transparent eye lens.

The antifungal activity of mupirocin

The antibacterial agent mupirocin (pseudomonic acid A) is used as a topical agent in the treatment of superficial infections by Gram-positive bacteria, particularly Staphylococcus aureus. However, we demonstrate here that the compound also inhibits the growth of a number of pathogenic fungi in vitro, including a range of dermatophytes and Pityrosporum spp. It inhibited the incorporation of amino acids and precursors of RNA, but not that of acetate, by Trichophyton mentagrophytes. It also inhibited the isoleucyl-tRNA synthetase from Candida albicans, indicating a mechanism of action similar to that in bacteria. When administered topically, mupirocin was efficacious in a T. mentagrophytes ringworm model in guinea pigs. These results suggest that mupirocin could have clinical utility for superficial infections caused by dermatophytes.

Efficacy of high-dose amoxicillin-clavulanate against experimental respiratory tract infections caused by strains of Streptococcus pneumoniae

The purpose of the present investigation was to determine if the efficacy of amoxicillin-clavulanate against penicillin-resistant Streptococcus pneumoniae could be improved by increasing the pediatric amoxicillin unit dose (90 versus 45 mg/kg of body weight/day) while maintaining the clavulanate unit dose at 6.4 mg/kg/day. A rat pneumonia model was used. In that model approximately 6 log10 CFU of one of four strains of S. pneumoniae (amoxicillin MICs, 2 microg/ml [one strain], 4 microg/ml [two strains], and 8 microg/ml [one strain]) were instilled into the bronchi of rats. Amoxicillin-clavulanate was given by computer-controlled intravenous infusion to approximate the concentrations achieved in the plasma of children following the administration of oral doses of 45/6.4 mg/kg/day or 90/6.4 mg/kg/g/day divided every 12 h or saline as a control for a total of 3 days. Infusions continued for 3 days, and 2 h after the cessation of infusion, bacterial numbers in the lungs were significantly reduced by the 90/6.4-mg/kg/day equivalent dosage for strains for which amoxicillin MICs were 2 or 4 microg/ml. The 45/6.4-mg/kg/day equivalent dosage was fully effective only against the strain for which the amoxicillin MIC was 2 microg/ml and had marginal efficacy against one of the two strains for which amoxicillin MICs were 4 microg/ml. The bacterial load for the strain for which the amoxicillin MIC was 8 microg/ml was not reduced with either dosage. These data demonstrate that regimens which achieved concentrations in plasma above the MIC for at least 34% of a 24-h dosing period resulted in significant reductions in the number of viable bacteria, indicating that the efficacy of amoxicillin-clavulanate can be extended to include efficacy against less susceptible strains of S. pneumoniae by increasing the amoxicillin dose.

Two pharmacodynamic models for assessing the efficacy of amoxicillin-clavulanate against experimental respiratory tract infections caused by strains of Streptococcus pneumoniae

Two models of respiratory tract infection were used to investigate the pharmacodynamics of amoxicillin-clavulanate against Streptococcus pneumoniae. Eight strains of S. pneumoniae were used in a mouse model in which the animals were infected intranasally and were then treated with a range of doses and dose intervals. The time that the plasma amoxicillin concentration remained above the MIC (T>MIC) correlated well with bacterial killing, such that if T>MIC was below 20% there was no effect on bacterial numbers in the lungs. As T>MIC increased, the response, in terms of decreased bacterial load, improved and at T>MICs of greater than 35 to 40% of the dosing interval, bacteriological cure was maximal. On the basis of equivalent T>MICs, these data would suggest that in humans a dosage of 500 mg three times daily (t.i.d.) should have efficacy equal to that of a dosage of 875 mg twice daily (b.i.d.). This hypothesis was evaluated in a rat model in which amoxicillin-clavulanate was given by computer-controlled intravenous infusion to achieve concentrations that approximate the concentrations achieved in the plasma of humans following oral administration of 500/125 mg t.i.d. or 875/125 mg b.i.d. Infusions continued for 3 days and bacterial numbers in the lungs 2 h after the cessation of the infusion were significantly reduced (P < 0.01) by both treatments in strains of S. pneumoniae for which amoxicillin MICs were below 2 microg/ml. When tested against a strain of S. pneumoniae for which the amoxicillin MIC was 4 microg/ml, the simulated 500/125-mg dose was ineffective but the 875/125-mg dose demonstrated a small but significant (P < 0. 01) reduction in bacterial numbers. These data confirm the findings in the mouse and indicate that amoxicillin-clavulanate administered at 875/125 mg b.i.d. would be as effective clinically as amoxicillin-clavulanate administered at 500/125 mg t.i.d.

Bacteriological efficacies of three macrolides compared with those of amoxicillin-clavulanate against Streptococcus pneumoniae and Haemophilus influenzae

Comparative antibacterial efficacies of erythromycin, clarithromycin, and azithromycin were examined against Streptococcus pneumoniae and Haemophilus influenzae, with amoxicillin-clavulanate used as the active control. In vitro, the macrolides at twice their MICs and at concentrations achieved in humans were bacteriostatic or reduced the numbers of viable S. pneumoniae slowly, whereas amoxicillin-clavulanate showed a rapid antibacterial effect. Against H. influenzae, erythromycin, clarithromycin, and clarithromycin plus 14-hydroxy clarithromycin at twice their MICs produced a slow reduction in bacterial numbers, whereas azithromycin was bactericidal. Azithromycin at the concentrations achieved in the serum of humans was bacteriostatic, whereas erythromycin and clarithromycin were ineffective. In experimental respiratory tract infections in rats, clarithromycin (equivalent to 250 mg twice daily [b.i.d.]) and amoxicillin-clavulanate (equivalent to 500 plus 125 mg b.i.d., respectively) were highly effective against S. pneumoniae, but azithromycin (equivalent to 500 and 250 mg once daily) was significantly less effective (P < 0.01). Against H. influenzae, clarithromycin treatment (equivalent to 250 or 500 mg b.i.d.) was similar to no treatment and was significantly less effective than amoxicillin-clavulanate treatment (P < 0.01). Azithromycin demonstrated significant in vivo activity (P < 0.05) but was significantly less effective than amoxicillin-clavulanate (P < 0.05). Overall, amoxicillin-clavulanate was effective in vitro and in vivo. Clarithromycin and erythromycin were ineffective in vitro and in vivo against H. influenzae, and azithromycin (at concentrations achieved in humans) showed unreliable activity against both pathogens. These results may have clinical implications for the utility of macrolides in the empiric therapy of respiratory tract infections.

Anterior polar cataract: clinical spectrum and genetic linkage in a single family

Anterior polar cataract can occur as a sporadic finding, in association with other ocular abnormalities or as an inherited, autosomal dominant disorder. We have demonstrated linkage in a family with autosomal dominant anterior polar cataract to the short arm of chromosome 17, locating the gene to the region 17p12-13. All affected members of this large family had an opacity at the anterior pole of the lens that varied only in size and the effect on visual acuity. Anterior polar cataract is thought to have a minimal effect on visual acuity although in the affected members of this family there was a high incidence of unilateral amblyopia.

A missense mutation in the human connexin50 gene (GJA8) underlies autosomal dominant "zonular pulverulent" cataract, on chromosome 1q

CZP1, a locus for autosomal dominant "zonular pulverulent" cataract, previously had been linked with the Duffy blood-group-antigen locus on chromosome 1q. Here we report genetic refinement of the CZP1 locus and show that the underlying mutation is present in GJA8, the gene for connexin50. To map the CZP1 locus we performed linkage analysis using microsatellite markers on two distantly related branches of the original Ev. pedigree, which now spans eight generations. Significantly positive two-point LOD score (Z) values were obtained for markers D1S2669 (maximum Z [Zmax] = 4.52; maximum recombination frequency [thetamax] = 0) and D1S514 (Zmax = 4.48; thetamax = 0). Multipoint analysis gave Zmax = 5.22 (thetamax = 0) at marker D1S2669. Haplotyping indicated that CZP1 probably lies in the genetic interval D1S2746-(20.6 cM)-D1S2771. Sequence analysis of the entire protein-coding region of the GJA8 gene from the pedigree detected a C-->T transition in codon 88, which introduced a novel MnlI restriction-enzyme site that also cosegregated with the cataract. This missense mutation is predicted to result in the nonconservative substitution of serine for a phylogenetically conserved proline (P88S). These studies provide the first direct evidence that GJA8 plays a vital role in the maintenance of human lens transparency and identify the genetic defect believed to underlie the first inherited disease to be linked to a human autosome.

A new locus for dominant "zonular pulverulent" cataract, on chromosome 13

Inherited cataract is a clinically and genetically heterogeneous disease that most often presents as a congenital autosomal dominant trait. Here we report the linkage of a new locus for dominant "zonular pulverulent" cataract (CZP) to chromosome 13. To map the CZP locus we performed molecular-genetic linkage analysis using microsatellite markers in a five-generation English pedigree. After exclusion of eight known loci and several candidate genes for autosomal dominant cataract, we obtained significantly positive LOD scores (Z) for markers D13S175 (maximum Z [Zmax] = 4.06; maximum recombination frequency [theta max] = 0) and D13S1236 (Zmax = 5.75, theta max = 0). Multipoint analysis gave Zmax = 6.62 (theta max = 0) at marker D13S175. Haplotype data indicated that CZP probably lies in the centromeric region of chromosome 13, provocatively close to the gene for lens connexin46.

A locus for autosomal dominant posterior polar cataract on chromosome 1p

Autosomal dominant congenital cataract is a clinically and genetically heterogeneous lens disease. Here we report the linkage of a locus for autosomal dominant posterior polar cataract (CPP) to the distal short arm of chromosome 1. To map the CPP locus we performed molecular genetic linkage analysis using microsatellite markers in a three-generation pedigree. After exclusion of 13 known loci and candidate lens genes for autosomal dominant cataract, we obtained significantly positive LOD scores for markers D1S508 (Z = 3.14, theta = 0) and D1S468 (Z = 2.71, theta = 0). Multipoint analysis gave a maximum LOD score of 3.48 (theta = 0.07) between markers D1S508 and D1S468. From haplotype data, however, CPP probably lies in the telomeric interval D1S2845-1pter, which includes the locus for the clinically distinct Volkman congenital cataract (CCV). This study provides the first evidence for genetic heterogeneity of autosomal dominant posterior polar cataract for which a locus had been linked previously to chromosome 16q.

A locus for autosomal dominant anterior polar cataract on chromosome 17p

Inherited cataract is a clinically and genetically heterogeneous disease. Here we report the identification of a new locus for an autosomal dominant anterior polar cataract on the short arm of chromosome 17. To map this new locus we performed genetic linkage analysis with microsatellite markers in a four-generation pedigree. After exclusion of seven candidate loci for cataract, we obtained significant positive LOD scores for markers D17S849 (Z = 4.01 / theta = 0.05) and D17S796 (Z = 4.17 / theta = 0.05). Multipoint analysis gave a maximum LOD score of 5.2 (theta max = 0.06) between these two markers. From haplotype analysis, the cataract locus lies in the 13 cM interval between markers D17S849 and D17S796. This study provides the first genetic mapping of an autosomal dominant anterior polar cataract.

Effect of protein binding on penetration of beta-lactams into rabbit peripheral lymph

The relevance of protein binding to penetration of beta-lactams into body fluids was investigated by examining the distribution of amoxicillin, ceftriaxone, clavulanic acid, temocillin, and ticarcillin into rabbit peripheral lymph after intravenous administration. The elimination half-lives in rabbit plasma varied between 0.34 h (temocillin) and 1.80 h (ceftriaxone), and the half-lives measured in lymph were similar to those in plasma (0.37 to 1.76 h). The percent penetration (area under the concentration-time curve in lymph/area under the concentration-time curve in plasma x 100) was high for amoxicillin (97.6%), temocillin (89.4%), and clavulanic acid (90.8%) but was lower for ticarcillin (76.0%) and for ceftriaxone (67.3%). There was a direct correlation between plasma protein binding and percent penetration. Correction for plasma and tissue binding increased the percent penetration for all compounds, and figures approached 100%. The results presented demonstrate the use of this model to examine the relationships between plasma pharmacokinetics, protein binding, and distribution of antibiotics.

The influence of uptake from the gastrointestinal tract and first-pass effect on oral bioavailability of (Z)-alkyloxyimino penicillins

We have investigated the contribution of uptake from the gastrointestinal tract and first-pass effect to the poor oral bioavailability of a series of (Z)-alkyloxyimino penicillins in mice. Investigative studies in gut sacs and perfused small intestine demonstrated that these penicillins were able to pass across the mucosal epithelium although to a lesser extent than amoxycillin and cyclacillin, both of which exhibit excellent oral bioavailability in man and animals. In the jejunal gut sacs the mucosal to serosal flux for BRL 44154 was approximately half that of amoxycillin and four times less than that of cyclacillin, and for all, uptake was pH dependent. The serosal to mucosal fluxes were however similar for these compounds and significantly lower than mucosal to serosal fluxes, suggesting involvement of carrier mechanisms in uptake from the mucosal surface. The order of results for the alkyloxyimino penicillins paralleled that observed for oral bioavailability in the mouse. For the alkyloxyimino penicillins, between 5.5 and 9.9% was taken up from the perfused intestine, values which were significantly less than those for amoxycillin (13.2%) and cyclacillin (33.3%). However, uptake was concentration-dependent for BRL 44154 as it was for amoxycillin, thus confirming the possible use of carrier mechanisms in absorption. These observations suggest that the poor peripheral blood concentrations of the alkyloxyimino penicillins achieved after oral dosing were not a consequence of the inability of the compounds to cross the mucosal epithelium. The biliary clearance of the alkyloxyimino penicillins was, however, considerably greater than for amoxycillin and cyclacillin, a finding which may well have been a contributory factor to the comparatively low peripheral concentrations of BRL 44154 and its analogues achieved after oral administration.

Bactericidal and morphological effects of amoxicillin on Helicobacter pylori

The growth kinetics of Helicobacter pylori after it has been exposed to amoxicillin have been investigated in conjunction with studies of cell morphology. A potent bactericidal effect was observed at concentrations 10-fold higher than the MIC, but this was accompanied by an increase in the residual numbers of coccoid forms observed. In the presence of 10 micrograms of amoxicillin per ml, these forms could be detected as rapidly as 6 h after exposure to the antibiotic. Although the clinical relevance of coccoid forms remains unknown, such forms should be considered when potential anti-Helicobacter agents are tested in vitro.

Characterization of a subtype of primary osteoclastoma: extracellular calcium but not calcitonin inhibits aggressive HLA-DR-positive osteoclastoma possessing 'functional' calcitonin receptors

We report here a case of primary osteoclastoma that despite possessing HLA-DR-positive status and 'functional' calcitonin receptors, exhibited aggressive in vitro and in vivo bone resorptive activity. In the osteoclast bone slice assay employing scanning electron microscopy, the giant cell-mediated bone resorption was uninhibited by salmon calcitonin (10 nM) and significantly inhibited by raised extracellular calcium (20 mM). In Fura-2AM based microspectrofluorimetric assays, the presence of the 'functional' calcitonin receptors was ascertained by a rise in intracellular calcium induced by calcitonin and high extracellular calcium. These findings provide evidence for a hitherto unrecognized subtype of giant cells that have HLA-DR-positive status, exhibit avid bone resorptive activity, but remain insensitive to calcitonin despite possessing calcitonin receptors.

Immunofluorescent evidence for the abundance of focal adhesion kinase in the human and avian osteoclasts and its down regulation by calcitonin

We show here that osteoclasts possess an abundant level of focal adhesion kinase, a novel cytosolic tyrosine kinase with unique structural features that may play an important role in the action of pp60c-src, cell surface integrins, and hormonal peptides. The presence of focal adhesion kinase in the bone cell osteoclast was determined using monoclonal antibodies to the kinase by employing immunofluorescent staining. The expression of focal adhesion kinase in the osteoclast was markedly suppressed following exposure to calcitonin. However, calcitonin-induced down regulation of the kinase was apparent only following a prolonged exposure. Our hypothesis that focal adhesion kinase is maximally expressed in the osteoclasts was confirmed when the transfection of avian osteoclasts and fibroblasts, with v-src containing plasmid pATV-8, induced increased expression of the kinase in the fibroblasts but did not alter the expression level of FAK in the osteoclasts.

Simulation of human serum pharmacokinetics of cefazolin, piperacillin, and BRL 42715 in rats and efficacy against experimental intraperitoneal infections

Studies were performed to determine the effects of BRL 42715, a potent beta-lactamase inhibitor, on the activity of cefazolin and piperacillin against experimental intraperitoneal infections caused by either Escherichia coli or Serratia marcescens in rats. Compounds were administered to rats as a continuous infusion of an exponentially diluted solution to simulate in rat plasma the concentration-versus-time curves obtained for humans following intravenous bolus administration. A simulated 1-g dose of cefazolin was ineffective in reducing the bacterial counts in blood and peritoneal fluid samples of animals infected with S. marcescens US20, which produced class Ia beta-lactamase, and as a result, mortality was similar to that of infected controls. Similarly, a simulated 2-g dose of piperacillin was ineffective in reducing bacterial numbers and mortality in animals infected with E. coli 41548, producing a TEM-1 beta-lactamase. However, when the antibiotics were coadministered with BRL 42715, bacterial numbers were reduced significantly and all animals survived at least 16 h after infection. These data demonstrate the ability of BRL 42715 to potentiate the activity of cefazolin and piperacillin against beta-lactamase-producing bacteria that would otherwise be resistant to these antibiotics and illustrate the application of a model to simulate human serum concentrations in conscious rats.

Dd-antigen-antibody system in five caste groups in north India

Antigen Dd, a polymorphic antigen found in extracts of certain human dandruff specimens, was investigated in five caste groups of north India. The incidence of antigen Dd-positive type varied from 21.21 per cent in Brahmins to 29.08 per cent in the Jat Sikhs of Punjab. However, a high frequency (45%) was observed in the Sunni Muslims of Kashmir, which differed significantly, when compared with different caste groups of Punjab. Family studies on 44 families indicated its inherited nature, the mode of inheritance being autosomal dominant.

Penetration of amoxycillin, ticarcillin and clavulanic acid into lymph after intravenous infusion in rabbits to simulate human serum pharmacokinetics

The distribution of amoxycillin, ticarcillin and clavulanic acid into lymph collected from the right lymphatic duct of rabbits was examined after intravenous administration. The compounds were administered to simulate, in the plasma of rabbits, the concentrations of amoxycillin, ticarcillin and clavulanic acid measured in human serum after the administration of either an iv bolus dose of amoxycillin 1.0 g plus clavulanic acid 200 mg, ticarcillin 3.0 g plus clavulanic acid 200 mg, or an iv infusion of amoxycillin 2.0 g plus clavulanic acid 200 mg or ticarcillin 3.0 g plus clavulanic acid 200 mg given over 30 min. Lymph concentrations of the compounds reached a peak rapidly after the simulation of a bolus dose (0-1 h) and the concentration-versus-time profiles in plasma and lymph were generally similar after 45 min. Following simulation of an iv infusion, peak concentrations of amoxycillin and clavulanic acid in lymph were reached at approximately the same time as for the bolus simulation, but that of ticarcillin occurred slightly later. The elimination half-lives of the compounds were similar in plasma and lymph. The percentage penetration values were high (greater than 80%) irrespective of the concentration-versus-time curve simulated. The penetration of clavulanic acid was compatible with that of the coadministered penicillin agent and was similar when given with either amoxycillin or ticarcillin.