Analysis of the Perception and Treatment of Osteoarthritis of the Knee Through Social Media: An Observational Study of the Top 100 Viral TikTok Videos

BACKGROUND

 TikTok is a popular platform that can be used for medical insights. However, spreading inaccurate information about diagnosing or treating medical conditions can undermine the quality of patient care. Our assessment focused on the discourse surrounding knee osteoarthritis on TikTok, with two primary objectives: 1) identifying the creators behind osteoarthritis-related content, and 2) examining whether a connection exists between the reach of video content and the strength of recommendations provided.

METHODS

 The top 100 TikTok videos were chosen based on likes on March 29, 2023. Posts were identified using the hashtag ("#Osteoarthritis"). Videos were classified by the following: number of likes, comments, shares, date of upload, uploader (medical professional, non-medical professional, or business), and video content (medical treatment, home remedy, personal story). Treatments were rated according to the American Academy of Orthopaedic Surgeons (AAOS) Evidence-Based Clinical Practice Guideline for Osteoarthritis using the strength of evidence criteria (1-4 stars). Descriptive and univariate analyses were performed.

RESULTS

 Among the top videos, 67.7% were uploaded by medical professionals. Private companies, despite having the highest average likes (29,681.2) and shares (1,367.5) per video, had a limited average evidence strength of 2.13. Physician-created videos had the second-highest average number of likes (25,440.1) and shares (1,224.5) per video with a strength of evidence of 3.03. Non-medical professional videos had the lowest evidence support (0.89). Medical treatments, the most liked and shared content, had the lowest evidence strength (1). There was no statistically significant correlation between the number of likes (p=0.808), comments (p=0.647), or shares (p=0.439) to the strength of evidence regarding the intervention.

DISCUSSION

 TikTok can be unreliable for knee osteoarthritis treatment information. It is common to find non-physicians sharing medical advice on the platform, with medical treatments demonstrating the weakest level of supporting evidence. Orthopaedic surgeons should advise their patients that TikTok treatment recommendations may not align with established guidelines.

The effect of obesity on complications following isolated posterior cruciate ligament reconstruction

BACKGROUND

This study assessed the risk of 30-day complications for obese patients compared to non-obese patients undergoing isolated posterior cruciate ligament (PCL) reconstruction.

METHODS

From 2006 to 2019, the National Surgical Quality Improvement Program database was queried for patients undergoing isolated PCL reconstruction. Two patient cohorts were defined: patients with obesity (BMI ≥ 30.0 kg/m²) and patients without obesity (BMI < 30 kg/m²). Patients' baseline demographics and medical comorbidities were collected and compared between the cohorts. Postoperative outcomes were assessed using bivariate and multivariate analyses.

RESULTS

414 patients underwent PCL reconstruction. 258 patients (62.3%) were non-obese and 156 patients (37.7%) were obese. Obese patients were more likely to be older, have a higher American Society of Anesthesiologists classification, and have hypertension compared to non-obese patients (p < 0.05 for all). The rates of superficial surgical site infections, wound dehiscence, transfusion necessity, deep vein thrombosis, and re-operation were not significant between obese and non-obese patients. Following adjustment on multivariate analyses, relative to patients without obesity, those with obesity had an increased risk of admission to the hospital overnight (OR 1.66; p = 0.048).

CONCLUSIONS

To our knowledge, this is the first study to evaluate obesity on complications in isolated PCL reconstruction. Our results and the heterogeneity in the literature indicate that obesity significantly impacts the rates of hospital readmission for PCL reconstruction. Therefore, surgeons should carefully weigh the risks and benefits of operating on obese patients and plan accordingly as obese patients may require postoperative hospital admission after PCL reconstruction.

LEVEL OF EVIDENCE

III.

An Analysis of Underrepresented in Medicine Away Rotation Scholarships in Surgical Specialties

BACKGROUND

Underrepresented in medicine (UIM) visiting student clerkship scholarships provide an opportunity for supporting diversity. Although these scholarships have become a popular initiative to recruit diverse surgical applicants, they have not been thoroughly analyzed regarding which programs offer scholarships and the characteristics of the scholarships. UIM scholarship opportunity disparities may exist depending on location, funding, reputation, and program size among different specialties.

OBJECTIVE

To describe the characteristics and prevalence of UIM visiting student scholarships by examining institutional and program websites for the surgical specialties.

METHODS

Using the Accreditation Council for Graduate Medical Education (ACGME) Accreditation Data System for 2021, residency training and diversity websites were identified and evaluated for the availability of UIM visiting student scholarships in July 2021. Eight surgical specialties were examined. Scholarships were categorized by how UIM was defined, the funding amount provided, and scholarship application requirements. We analyzed the association of the program's National Institutes of Health funding, size, type, region, reputation, and population density of the program's area via Doximity on scholarship availability using chi-square and multivariate analysis.

RESULTS

Of the 1058 analyzed programs, 314 (29.7%) had a UIM visiting student scholarship. There were 4 different definitions of UIM used among the analyzed programs. The average scholarship amount offered was $1,852.25 ($500-$4,000). Depending on the specialty, different variables were associated with whether a program had a UIM scholarship.

CONCLUSIONS

Currently, UIM scholarship offerings were variable between programs and surgical specialties.

Child and Adolescent Psychiatry Fellowship Program Website Content and Accessibility

OBJECTIVE

When child and adolescent psychiatry fellowship applicants are applying to programs, many will use fellowship websites to gather information. This study assesses the accessibility and content available on child and adolescent fellowship websites.

METHODS

Using the Electronic Residency Application Service (ERAS) list of child and adolescent fellowship programs for 2020, 139 child and adolescent fellowship training websites were compiled. Information on websites was evaluated within the following three categories: program overview, application information and recruitment, and educational opportunities. A total of 22 criteria were evaluated within these three categories. Descriptive statistics were used to analyze the websites.

RESULTS

A list provided by ERAS and a Google search identified child and adolescent fellowship program websites. Analysis of content revealed most websites included an overview of the program (97.8%), but fewer included information such as the number of fellowship spots (51.5%), salary (45.5%), application deadline (41.0%), and call responsibility (19.4%).

CONCLUSION

Results suggest there is room for improvement in the comprehensiveness and accessibility of child and adolescent fellowship websites. Especially during a time when much of the programmatic information will be obtained virtually due to COVID-19, it is critical that fellowship websites are uniformly curated so applicants can more easily find information about programs.

Increased severity of anaemia is associated with 30-day complications following total joint replacement

Aims

The aim of this study was to determine the impact of the severity of anaemia on postoperative complications following total hip arthroplasty (THA) and total knee arthroplasty (TKA).

Methods

A retrospective cohort study was conducted using the American College of Surgeons National Quality Improvement Program (ACS-NSQIP) database. All patients who underwent primary TKA or THA between January 2012 and December 2017 were identified and stratified based upon hematocrit level. In this analysis, we defined anaemia as packed cell volume (Hct) < 36% for women and < 39% for men, and further stratified anaemia as mild anaemia (Hct 33% to 36% for women, Hct 33% to 39% for men), and moderate to severe (Hct < 33% for both men and women). Univariate and multivariate analyses were used to evaluate the incidence of multiple adverse events within 30 days of arthroplasty.

Results

Following adjustment, patients in the THA cohort with moderate to severe anaemia had an increased odds of 6.194 (95% confidence interval (CI) 5.679 to 6.756; p < 0.001) for developing any postoperative complication. Following adjustment, patients in the TKA cohort with moderate to severe anaemia had an increased odds of 5.186 (95% CI 4.811 to 5.590; p < 0.001) for developing any postoperative complication. Among both cohorts, as severity increased, there was an increased risk of postoperative complications.

Conclusion

Preoperative anaemia is a risk factor for complications following primary arthroplasty. There is a significant relationship between the severity of anaemia and the odds of postoperative complications. Patients who had moderate to severe anaemia were at increased risk of developing postoperative complications relative to patients with mild anaemia. When considering elective primary THA or TKA in a moderately or severely anaemic patient, surgeons should strongly consider correcting anaemia prior to surgery if possible. Cite this article: Bone Joint J 2020;102-B(4):485–494.

Gross motor skills of South African preschool-aged children across different income settings

OBJECTIVES

No studies have investigated gross motor skill (GMS) proficiency of preschool-aged children across different income settings in South Africa. Research from high-income countries suggests that children from low-income settings display poorer GMS proficiency compared to higher-income peers. This study aimed to (1) describe GMS proficiency of preschool-aged children in urban high-income (UH), urban low-income (UL) and rural low-income (RL) settings; and (2) explore differences in proficiency between income settings and sex.

DESIGN

Descriptive cross-sectional study.

METHODS

The Test of Gross Motor Development-Edition 2 (TGMD-2) was used to assess GMS. The TGMD-2 gross motor quotient, standardised scores and raw scores were used to describe proficiency.

RESULTS

GMS proficiency was assessed in n=259 3-6-year-old children (n=46 UH, n=91 UL, n=122 RL). Overall, 93% of the children were classified as having 'average' or better GMS. According to TGMD-2 standardised scores, the RL children performed significantly better than UH and UL children (p=0.028 and p=0.009, respectively). RL children were significantly more proficient than UH and UL children in the strike and horizontal jump when comparing raw scores. Overall, boys performed significantly better than girls in the strike, stationary dribble, kick and leap when comparing raw scores (all p<0.001).

CONCLUSIONS

This study reports high GMS proficiency in preschool-aged children across income settings in South Africa. The factors associated with higher GMS in low-income settings are not immediately obvious. Thus, future research should explore potential factors and identify opportunities to ensure that GMS proficiency is capitalised on as preschool-aged children enter formal schooling.

Postnatal growth of the human optic nerve

PurposeAlthough the length of the average human adult optic nerve (ON) is known, the average length of the normal full-term, newborn ON has never been adequately evaluated, nor has the in vivo growth rate of the human ON been determined. We wanted to identify both the average length of the newborn human ON and its rate of anteroposterior growth.Patients and methodsUsing MRIs from a newly generated set of normal newborn infants rescanned at 1 year, and from different aged groups, we calculated average newborn ON length and growth rate.ResultsThe newborn human ON is 25.3±0.3 mm in length from globe to chiasm, and grows by 80% in length after birth, with maximum speed of elongation occurring in the first 3 years of life, attaining full length by 15 years of age.ConclusionThe human ON grows dramatically in the first 3 years of life, and continues to grow for the first two decades. These data are relevant for pediatric treatments that may impede or alter orbital growth in infants, and maximal susceptibility to oncological procedures in early childhood.

Heat shock protein 90 in retinal ganglion cells: association with axonally transported proteins

The mRNAs for heat shock protein 90 (HSP90) are found at highest levels (differentially expressed) in the primate retinal fovea, the region of highest visual acuity, compared to the peripheral retina. HSP90 expression and retinal associations were analyzed by immuno-localization, in situ hybridization, and western analysis. Retinal ganglion cells (RGCs) express much of the HSP90 mRNA present in the primate retinal fovea. A large fraction of RGC synthesized HSP90 is apparently present in the axonal compartment. To identify the role of HSP90 protein in the optic nerve and retina, co-immunoprecipitation experiments were performed, using antibodies specific for HSP90 isoforms. The immunoprecipitates were analyzed for neurotrophin receptor and ligand activities, and MAP kinase activity. MAP kinase assay was used to determine the activation state of MAP kinase associated with HSP90. HSP90 proteins selectively associate with the inactive form of full-length tyrosine kinase growth factor receptor trkB, suggesting utilization during anterograde axonal transport. Activated MAP kinase, associated with the trk downstream signaling cascade, was found to co-immunoprecipitate with optic nerve HSP90, suggesting that HSP90 may be utilized in retrograde transport of the secondary messengers associated with neurotrophin signaling. HSP90 can thus be hypothesized to play a role in bidirectional RGC axonal protein transport.

Saturating density of STSs (1/6 kb) in a 1.1 Mb region on 3q28-q29: a valuable resource for cloning of disease genes

We have fine mapped 29 ESTs of Genemap'99 to YACs and radiation hybrids covering 8 cM of the chromosomal region of 3q28-q29. Focusing on the genetic interval of approximately 1 Mb between markers D3S3669 and D3S3562 we established a sequence-ready PAC contig which covers the OPA1 locus containing the gene causing autosomal dominant optic atrophy (ADOA; OMIM*165500). The fidelity of the contig was increased by the generation of 181 PAC end sequences, 84 of which resulted in PCR-able STSs. Sequence content evaluation of the PAC ends by BLAST analysis identified two novel ESTs localising to the OPA1 crucial interval.

Clusterin protein diversity in the primate eye

PURPOSE

The clusterin gene encodes a multi-functional protein that has been identified in different tissues, including a number of different eye tissues, primarily in the mouse and to a much lesser extent in humans. Clusterin has been implicated in a number of cellular processes such as lipid transport, membrane integrity, apoptosis, and neurodegeneration, all of which could be important to the biology of the eye. In the current communication, we provide data that confirms the expression of clusterin in a number of different human eye tissues and establishes the expression profile of this gene in monkey derived eye tissues. The issue that we sought to examine is whether a broad profile of clusterin expression in the eye is consistent in primates (monkey and human).

METHODS

The majority of our study was done using monkey eye tissues. Where possible, we have used human tissues in order to confirm published findings. Northern and western analysis was performed using tissues derived from monkey eyes. In situ hybridization and immunochemistry were carried out on human eye sections.

RESULTS

Clusterin mRNA is expressed in primate lens, cornea, limbus, sclera, orbital muscle, ciliary body, retina, RPE/choroid, and RPE cells in culture. Western analysis revealed that two major groups of clusterin exist in the eye, a high molecular weight group (>100 kDa) and a second group consisting of at least five clusterin species that are all approximately 80 kDa. Analysis of conditioned media from RPE cells cultured on permeable supports suggests that different forms of clusterin display alternative patterns of secretion.

CONCLUSIONS

Clusterin is expressed in a broad range of eye tissues in both human and monkey, suggesting that this is a characteristic feature in primates. We demonstrate for the first time that a diverse number of clusterin isoforms were observed in monkey eye tissues by western analysis. Meanwhile, the molecular size of clusterin mRNA detected in the array of tissues are identical in size, suggesting that the nature of the diversity in clusterin forms is due to post-translational modifications. In addition, new insights were made in defining clusterin expression in ciliary body, cornea, and the retinal pigment epithelium.

Heat shock cognate-70 gene expression declines during normal aging of the primate retina

PURPOSE

Despite documented age-related changes in retinal function and histology, little is known about the pattern of gene expression during normal aging of the vertebrate retina. This study was undertaken to definitively characterize gene expression in the primate retina during aging.

METHODS

Human retina cDNA library clones were arrayed at high density on nylon membranes and screened with mixed cDNA probes generated from young (4-year-old) and old (80-year-old) human retinae. Clones showing a more than twofold difference in intensity were rescreened by dot blot analysis with the same probes and with mixed cDNA probes generated from young (2-3 years) and old (27-35 years) rhesus monkeys. One clone identified by its differential (age-putative) signal, and age-related differential expression was used for analysis of Northern blot analysis of total retinal RNA from human donors (35 weeks to 94 years of age) and two rhesus monkeys (2 and 27 years of age). The identified clone was sequenced and compared with entries in the GenBank/EMBL databases. Western blot analysis was performed on protein isolated from the retina of human donors aged 4 to 64 years and rhesus monkeys aged 18 months and 35 years.

RESULTS

Approximately 1.6% of the 55,368 retina-expressed sequences examined show age-related changes between tissues from young and old donors. The mRNA level one clone, identical with heat shock cognate (HSC)70, was altered during normal retinal aging in primates. Regression analysis of Northern blot analysis signals from 23 human donors suggested that there may be a two- to threefold decrease in HSC70 mRNA levels in the human retina by the eighth decade of life. Western blot analysis also showed lower levels of the 70-kDa HSC protein in older tissues of both primates.

CONCLUSIONS

HSC70 mRNA levels apparently decline during normal aging of the primate retina. Because the heat shock 70 protein family may play important roles in ocular development and protection from various biologic and environmental stresses, decreased HSC70 levels in the retina during aging may contribute to the apparent increased susceptibility of the retina to age-acquired retinal disease.

Crystal structure and mutational analysis of the Saccharomyces cerevisiae cell cycle regulatory protein Cks1: implications for domain swapping, anion binding and protein interactions

BACKGROUND

The Saccharomyces cerevisiae protein Cks1 (cyclin-dependent kinase subunit 1) is essential for cell-cycle progression. The biological function of Cks1 can be modulated by a switch between two distinct molecular assemblies: the single domain fold, which results from the closing of a beta-hinge motif, and the intersubunit beta-strand interchanged dimer, which arises from the opening of the beta-hinge motif. The crystal structure of a cyclin-dependent kinase (Cdk) in complex with the human Cks homolog CksHs1 single-domain fold revealed the importance of conserved hydrophobic residues and charged residues within the beta-hinge motif.

RESULTS

The 3.0 A resolution Cks1 structure reveals the strict structural conservation of the Cks alpha/beta-core fold and the beta-hinge motif. The beta hinge identified in the Cks1 structure includes a novel pivot and exposes a cluster of conserved tyrosine residues that are involved in Cdk binding but are sequestered in the beta-interchanged Cks homolog suc1 dimer structure. This Cks1 structure confirms the conservation of the Cks anion-binding site, which interacts with sidechain residues from the C-terminal alpha helix of another subunit in the crystal.

CONCLUSIONS

The Cks1 structure exemplifies the conservation of the beta-interchanged dimer and the anion-binding site in evolutionarily distant yeast and human Cks homologs. Mutational analyses including in vivo rescue of CKS1 disruption support the dual functional roles of the beta-hinge residue Glu94, which participates in Cdk binding, and of the anion-binding pocket that is located 22 A away and on an opposite face to Glu94. The Cks1 structure suggests a biological role for the beta-interchanged dimer and the anion-binding site in targeting Cdks to specific phosphoproteins during cell-cycle progression.

Regional expression of disease-related genes in human and monkey retina

PURPOSE

Although specific genes play a role in regional retinal disease, the correlation of regional gene expression in the disease-affected site has not been previously ascertained. Non-human primates are widely used in models of human retinal function and are theorized to have identical (to human) patterns of expression, but no correlation between primate and human regional retinal gene expression has ever been performed. We wanted to evaluate the pattern of regional gene expression for a number of genes whose dysfunctions are known to selectively affect specific regions of the human retina, and to determine whether patterns of regional gene expression in nonhuman primates correlate with the human.

METHODS

Human and rhesus monkey eyes were dissected into retina, retinal pigment epithelium (RPE)/choroid and isolated RPE. Retinal regions were dissected, total RNA was isolated and northern analysis performed. Complementary DNA (cDNA) probes were prepared from genes associated with regional retinal disease. These genes are: rod opsin, the alpha-subunit of rod phosphodiesterase, RDS-peripherin, rod outer membrane (ROM) protein, ornithine aminotransferase (OAT), choroideremia gene product (CHM), tissue specific inhibitor of metalloproteinases-3 (TIMP-3), and red/green photoreceptor pigment protein. We also compared expression of Norrie disease product (NDP), a gene whose mutation is known to globally affect the retina.

RESULTS

Rod-specific mRNA expression is highest in the retinal midperiphery, and cone-specific mRNA levels were highest in total RNA from the cone-dominant fovea. mRNA levels for genes coding for proteins expressed in both rod- and cone photoreceptors (RDS-peripherin and ROM-1) are also highest in total RNA from the retinal midperiphery. Regional mRNA levels of CHM and OAT do not directly correlate with their patterns of disease expression. NDP mRNA expression was equivalent in both fovea and midperipheral retina total RNA. Patterns of gene expression were qualitatively similar for both human and rhesus monkey retina.

CONCLUSIONS

Regional retinal gene expression is an important factor in regional disease. However, for genes not solely expressed by a single photoreceptor subtype, other factors, such as regional metabolic differences, intra- and intercellular interactions, are also likely to be important in predisposing a single retinal region to disease. The pattern of neural retina OAT mRNA expression may have important implications in determining the appropriate tissue approach in gene therapy for gyrate atrophy. Regional retinal gene expression likely plays a significant, but nonexclusive role in the development of regional retinal disease.

Emergency medicine in the New Delhi area, India

An overview of emergency medical care in the New Delhi area is presented. Emergency medicine does not exist as an organized specialty, and emergency departments are staffed by a combination of residents and attending physicians from various specialties. An infrastructure for providing emergency care exists at all levels of the state-owned medical system, and in private hospitals. At every level, medical centers lack adequate resources to manage the breadth of clinical problems encountered. Tertiary EDs care for large numbers of patients with high-severity conditions. Like their Western counterparts, urban EDs in New Delhi serve a diverse population with many indigent patients. Injury and gastrointestinal illness are the most common reasons for ED use. Organized prehospital care is scanty. A survey conducted at a leading medical school and hospital in New Delhi shows medical students and physicians are highly interested in the development and practice of emergency medicine as a specialty. This interest can be nurtured through continued international collaboration.

Intraarterial vs intravenous administration of antivenin for the treatment of Crotalidae atrox envenomation: a pilot study

OBJECTIVE

Standard therapy for significant snake envenomation includes antivenin. i.v. administration is currently the only recommended route. Intraarterial (i.a.) administration has potential advantages over i.v. that could improve outcome. To study this, the authors compared i.v. and i.a. antivenin administrations for the treatment of experimental snake envenomations.

METHODS

14 adult female swine were anesthetized and prepared with femoral artery and ear vein catheters, and baseline hoof, forearm, and thigh circumference and volume displacement measurements were taken. Crotalidae atrox venom was injected into the subcutaneous tissue of the hoof. The doses of venom were 4.75, 9.50, 19.00, 37.90, 47.30, 56.90, and 66.40 mg. Immediately following injection of venom, polyvalent antivenin (Crotalidae) (0.285 mg/10 mL saline) was infused over 30 minutes into the femoral artery (i.a. group) or ear vein (i.v. group). As a control, 10 mL of saline was infused into the ear vein (i.a. group) or femoral artery (i.v. group). Measurements were recorded up to 48 hours. Linear mixed-effect regression models were used for each measurement and to compare the i.a. and i.v. groups.

RESULTS

Venom dose and time after administrations were associated with increased circumferences and increased volumes (p < 0.05). i.v. administration was associated with larger hoof (1.26 cm) and forearm (0.42 cm) sizes and volume displacement (21.71 mL) when compared with i.a. administration ( p < 0.05).

CONCLUSION

i.a. antivenin results in a modest but significant decrease in tissue edema when compared with i.v..

Region specific mitochondrial gene expression in the human retina

The human mitochondrial genome has not been previously known to differentially express specific mRNA transcripts. Results of northern analysis, using total RNA from two different retinal regions, demonstrate that there is differential expression of five mitochondrial genes. There is a correlation of regional expression of one of these differentially expressed genes with the gene responsible for the majority of cases of foveo-macular mitochondropathy. These findings suggest that there is selective control over specific mitochondrial messenger steady state levels.

A mutation in the human cyclin-dependent kinase interacting protein, CksHs2, interferes with cyclin-dependent kinase binding and biological function, but preserves protein structure and assembly

A mutation directing an amino acid substitution in the conserved beta-hinge region of one of the human Cks isoforms, CksHs2, was constructed by site-directed mutagenesis. Replacement of glutamine for glutamate 63 (E63Q) was predicted to stabilize the beta-interchanged dimeric and hexameric assembly of CksHs2. However, such an effect was seen only at high, non-physiological pH. Three-dimensional structures of the E63Q hexameric mutant protein were determined to 2.6 A resolution in a P4(3)2(1)2 space group and 2.1 A in the C2 space group isostructural with wild-type, and both were shown to be virtually identical to the refined 1.7 A wild-type structure. Thus, the E63Q mutation did not alter the wild-type structure and assembly of CksHs2 but, surprisingly, disrupted the essential biological function of the protein and significantly reduced its ability to bind to cyclin-dependent kinases. The Kd of wild-type CksHs2 for CDK2 was 5.05 x 10(-8) M, whereas the affinity of the mutant protein for CDK2 was too low to allow a determination. These data, coupled with the observation that monomeric but not hexameric CksHs2 interacts with cyclin-dependent kinases, suggest that glutamine 63 is likely to be directly involved in cyclin-dependent kinase binding in vitro and in vivo.

Characterization of a human fovea cDNA library and regional differential gene expression in the human retina

The primate fovea is the region of the retina responsible for acute vision. This region constitutes less than 5% of the total area of the retina and has not been intensely studied at the molecular level. As a first step in the molecular characterization of the fovea, we have constructed a primary human fovea cDNA library. Experiments confirm that our cDNA library reflects a nonbiased distribution of foveal expressed sequences. Single-pass sequencing was performed on 209 randomly isolated clones from this library. Analysis of the sequences generated reveals that the distributions of fovea clones with either human mitochondrial gene sequences or repetitive elements are different than those observed in cDNA libraries made from other tissues. A significant number of the fovea expressed sequence tags (ESTs) (88, 42.1%) represent novel human ESTs. This suggests that the library will be useful in identifying new human genes. Northern analysis of specific fovea ESTs defined in this study suggests that there are significant quantitative differences in gene expression that distinguish the fovea from the rest of the retina.

Assembly and antigenicity of the Neisseria gonorrhoeae pilus mapped with antibodies

The relationship between the sequence of Neisseria gonorrhoeae pilin and its quaternary assembly into pilus fibers was studied with a set of site-directed antibody probes and by mapping the specificities of antipilus antisera with peptides. Buried and exposed peptides in assembled pili were identified by competitive immunoassays and immunoelectron microscopy with polyclonal antibodies raised against 11 peptides spanning the pilin sequence. Pili did not compete significantly with pilin subunits for binding to antibodies against residues 13 to 31 (13-31) and 18-36. Pilus fibers competed well with pilin protein subunits for binding to antibodies raised against peptides 37-56, 58-78, 110-120, 115-127, 122-139, and 140-159 and competed weakly for antibodies against residues 79-93 and 94-108. Antibodies to sequence-conserved residues 37-56 and to semiconserved residues 94-108 preferentially bound pilus ends as shown by immunoelectron microscopy. The exposure of pilus regions to the immune system was tested by peptide mapping of antiserum specificities against sets of overlapping peptides representing all possible hexameric or octameric peptides from the N. gonorrhoeae MS11 pilin sequence. The immunogenicity of exposed peptides incorporating semiconserved residues 49-56 and 121-126 was revealed by strong, consistent antigenic reactivity to these regions measured in antipilus sera from rabbits, mice, and human and in sera from human volunteers with gonorrhea. The conservation and variation of antigenic responses among these three species clarify the relevance of immunological studies of other species to the human immune response against pathogens. Overall, our results explain the extreme conservation of the entire N-terminal one-third of the pilin protein by its dominant role in pilus assembly: hydrophobic residues 1-36 are implicated in buried lateral contacts, and polar residues 37-56 are implicated in longitudinal contacts within the pilus fiber.

Isolation of differentially expressed human fovea genes: candidates for macular disease

PURPOSE

In humans, the fovea is the region of the retina responsible for acute vision. Disorders affecting the fovea are responsible for the majority of cases of untreated blindness in the developed world, yet are poorly understood at the molecular level. Our goal is to identify genes that are preferentially expressed within the human fovea as compared to the midperipheral retina (differential fovea clones).

MATERIALS AND METHODS

An unamplified fovea cDNA library was differentially screened with cDNA probes derived from either human fovea or midperipheral retina. Rounds of secondary screening and northern analysis were used to verify the expression pattern of a selective number of clones isolated.

RESULTS

Forty-one differential fovea clones were isolated from a screening of 10,000 phage clones (clones). Of these clones, 31.5 % correspond to known sequences present in GenBank/EMBL and 70.7% represent novel human fovea expressed sequence tags (ESTs). Northern analysis of selected clones demonstrated that they represent genes expressed at higher levels in the human fovea than in the midperipheral retina.

CONCLUSIONS

Genes that are more highly expressed in the fovea as opposed to the midperipheral retina are likely to represent essential genes for fovea function. Using our fovea cDNA library, we are able to isolate differential human fovea clones at an incidence of 41/10,000 clones screened. We demonstrate that there is a high level of differential gene expression within different regions of the human retina.

Crystal structure of the cell cycle-regulatory protein suc1 reveals a beta-hinge conformational switch

The Schizosaccharomyces pombe cell cycle-regulatory protein suc1, named as the suppressor of cdc2 temperature-sensitive mutations, is essential for cell cycle progression. To understand suc1 structure-function relationships and to help resolve conflicting interpretations of suc1 function based on genetic studies of suc1 and its functional homologs in both lower and higher eukaryotes, we have determined the crystal structure of the beta-interchanged suc1 dimer. Each domain consists of three alpha-helices and a four-stranded beta-sheet, completed by the interchange of terminal beta-strands between the two subunits. This beta-interchanged suc1 dimer, when compared with the beta-hairpin single-domain folds of suc1, reveals a beta-hinge motif formed by the conserved amino acid sequence HVPEPH. This beta-hinge mediates the subunit conformation and assembly of suc1: closing produces the intrasubunit beta-hairpin and single-domain fold, whereas opening leads to the intersubunit beta-strand interchange and interlocked dimer assembly reported here. This conformational switch markedly changes the surface accessibility of sequence-conserved residues available for recognition of cyclin-dependent kinase, suggesting a structural mechanism for beta-hinge-mediated regulation of suc1 biological function. Thus, suc1 belongs to the family of domain-swapping proteins, consisting of intertwined and dimeric protein structures in which the dual assembly modes regulate their function.

Purification and crystallization of a schistosomal glutathione S-transferase

The 26-kDa glutathione S-transferase from Schistosoma japonica (Sj26), a potential antischistosomal vaccine antigen, has been crystallized in an unligated form. Sj26 was recombinantly produced in E. coli without using a glutathione affinity column to facilitate preparation of unligated enzyme. The recombinant protein contains all 218 residues of Sj26 and an additional 13 residues linked to the C-terminus. Crystals of recombinant Sj26 were obtained by the vapor diffusion method using ammonium sulfate as the precipitant at pH 5.6. The crystals belong to the hexagonal space group P6(3)22 with unit cell dimensions a = b = 125.2 A and c = 72.0 A and contain one Sj26 monomer per asymmetric unit. A complete native diffraction data set has been obtained to 2.4 A resolution.

Expression of retina-specific genes by mouse retinoblastoma cells

PURPOSE

Two cell lines derived from ocular tumors of a transgenic mouse expressing the SV40 large T antigen have been established as models of human retinoblastoma. One line, TM, originated from a metastasis, and the other, TE, originated from the primary tumor. The authors compared these two lines with the normal adult mouse eye by analysis of the expression of five photoreceptor cell-specific proteins: IRBP, opsin, rod- and cone-specific transducins, and S-antigen. The authors sought to determine which of these proteins was expressed qualitatively and to examine semi-quantitatively for changes in the levels of expression in the cell lines.

METHOD

Western blot analysis was used to detect photoreceptor-specific intracellular or secreted proteins. Total RNA was prepared from cultured cells or from mouse adult whole eye. Specific messenger levels in total RNA were determined either by northern hybridization analysis or by a semi-quantitative polymerase chain reaction (PCR), coupled to complementary DNA (cDNA) substrates prepared from total RNA.

RESULTS

IRBP was present in the retinoblastoma cell lines and secreted into the medium. Neither S-antigen nor opsin were detectable by immunoblotting. IRBP and cone transducin mRNA were present in both cell lines. In contrast, opsin, rod transducin, and S-Antigen mRNAs were not detectable by PCR. beta-actin was present in the mRNA populations of whole eye and retinoblastoma. SV40 large T antigen mRNA was present only in retinoblastoma cells.

CONCLUSIONS

IRBP and cone transducin expression in mouse retinoblastoma cells is independent of signaling provided directly or indirectly through large T antigen or Rb105 regulatory cascades. The pattern of photoreceptor-specific gene expression is similar to that seen in human retinoblastoma cell lines. These murine-derived cell lines may be useful as a tool to study IRBP and cone transducin expression in vitro and to determine early retinoblast expression patterns in the mouse.

Impact of Yankee Stadium Bat Day on blunt trauma in northern New York City

STUDY OBJECTIVE

To determine the incidence of blunt trauma in northern New York City before and after the distribution of 25,000 baseball bats at Yankee Stadium.

DESIGN

Prospective multicenter study, including ten days before and ten days after Bat Day (June 3, 1990).

SETTING

Ten emergency departments in the Bronx and northern Manhattan.

TYPE OF PARTICIPANT

All patients presenting to the ED with baseball bat injuries.

INTERVENTIONS

Each hospital collected the following data for each subject: date and time of injury, patient's age and sex, extent of injury, whether a Yankee bat was used, presence of loss of consciousness, results of computed tomography scan of the brain (if performed), history source, and disposition of the patient. Average daily atmospheric temperature was recorded for each day of the study.

MEASUREMENTS AND MAIN RESULTS

Seventy-seven patients sustained bat injuries, 38 (49%) before and 36 (47%) after Bat Day. There were no significant differences between the two groups with respect to age, sex, time of injury, number and distribution of fractures and lacerations, incidence of loss of consciousness, source of history, or dispostion. There was a positive association between the number of cases on a given day and the average temperature that day (r = .5; P < .01).

CONCLUSION

The distribution of 25,000 wooden baseball bats to attendees at Yankee Stadium did not increase the incidence of bat-related trauma in the Bronx and northern Manhattan. There was a positive correlation between daily temperature and the incidence of bat injury. The informal but common impressions of emergency clinicians about the cause-and-effect relationship between Bat Day and bat trauma were unfounded.

Biochemical purification and crystallographic characterization of the fiber-forming protein pilin from Neisseria gonorrhoeae

Pilus fibers are long protein filaments on many pathogenic bacteria that participate in attachment to host cells. Although the self-assembling protein pilin is the major structural component of the Neisseria gonorrhoeae pilus fiber, several other proteins co-purified with pilin through the repeated solubilization-reassociation steps of the biochemical purification. Pilin solubilized in the nondenaturing detergent n-octyl-beta-D-glucopyranoside remained an aggregate of about 100 kDa at pH 9.5, but was reduced to a 40-kDa dimer at pH 10.5, suggesting that assembly involves electrostatic interactions of lysine, tyrosine, or other side chains with high pKa values. Pilin dimers and aggregates of higher molecular mass were partially stable even in the presence of sodium dodecyl sulfate and beta-mercaptoethanol. Removal of pilus-associated proteins and stabilization of pilin multimers permitted the reproducible crystallization of pilin. Three-dimensional needle- and plate-shaped crystals of purified N. gonorrhoeae pilin (strain MS11 variant C30) grew from 36 to 40% polyethylene glycol 400, pH 8.0-9.0, in space group C222, with cell dimensions a = 126.4, b = 121.2, c = 26.7 A and Vm = 2.84 A3/dalton for one molecule per asymmetric unit. The best crystals diffracted to 2.4 A resolution using synchrotron radiation, were stable to x-ray damage, and appear suitable for determination of the atomic structure. This approach of stabilizing and crystallizing an intermediate assembly state may be useful for other fiber-forming proteins, which have previously not been successfully crystallized in forms that diffract to atomic resolution.

Three dimensional structure of bacterial pili

Crystallographic and associated biochemical and structural studies are in progress on the fiber-forming pilin proteins of the gonococcal pilus. Preparative scale purification procedures have been developed for the gonococcal pilin protein, which appear generally applicable to bacterial pilins. For three gonococcal pilin protein strains, we have obtained both reassembled pilus fibers and three-dimensional crystals. One needle-shaped crystal form of gonococcal C30 pilin diffracts beyond 3 A resolution using synchrotron x-ray radiation. A diffraction data set to 3.5 A resolution has been collected on these needle-shaped crystals (lattice spacings a = 125.4(3) b = 120.4(3), c = 26.61(4) A) in which the packing arrangement of the pilin subunits appears to resemble that seen in the pilus fibers using electron microscopy. X-ray diffraction data confirm our proposed model for the overall polypeptide fold of a pilin subunit, which is an antiparallel 4-alpha helix bundle similar to tobacco mosaic virus coat protein and myohemerythrin.

Changes in gene expression during postnatal development of the rat cerebellum

The base sequence complexity of total and polysomal poly(A +)RNA from rat cerebellum was measured during postnatal development by RNA-DNA hybridization. At saturation, total and polysomal poly(A +)RNA from neonate cerebellum hybridized to 12.7% and 5.0% of the single-copy genomic DNA, respectively. Assuming asymmetric transcription, the sequence complexity of these RNA populations is sufficient to code for greater than 100,000 different gene transcripts. The percentage of single-copy DNA expressed as total and polysomal poly(A +)RNA declined during postnatal development, reaching adult values of 10.0% and 4.1%, respectively. These results indicate that cerebellar maturation is accompanied by significant reductions in the diversity of genetic information expressed in the tissue.

An improved method for the rapid isolation of brain ribonucleic acid

An improved one-step method for the extraction of RNA from rat brain is described. Fresh or frozen tissue is disrupted in the powerful protein denaturant guanidine thiocyanate, and RNA isolated by ultracentrifugation through CsCl. The procedure is advantageous in that it is relatively simple, is rapid and does not expose the sample to enzyme treatments or repeated organic extractions.