Approach for defining human adenovirus infection and disease for central review adjudication in clinical studies

BACKGROUND

Pediatric allogeneic hematopoietic cell transplant (allo-HCT) recipients are at risk for morbidity and mortality from human adenovirus (HAdV). HAdV can be detected in an asymptomatic state, referred to as infection or with signs or symptoms of illness, referred to as disease. Standardized case definitions are needed to distinguish infection from disease and allow for consistent reporting in both observational cohort studies and therapeutic clinical trials.

METHODS

A working group of experts in virology, transplant infectious disease, and HCT was assembled to develop HAdV infection and disease definitions with the degree of certainty (i.e., possible, probable, and proven). Definitions were further refined through an iterative process and independently applied by two central review committees (CRCs) to 20 pediatric allo-HCT recipients with at least one HAdV-positive PCR.

RESULTS

Initial HAdV infection and disease definitions were developed and updated through an iterative process after reviewing clinical and virological details for 81 subjects with at least one positive HAdV PCR detected in a clinical specimen. Independent application of final definitions to 20 HAdV positive allo-HCT recipients by two CRCs yielded similar number of HAdV infection or disease events but with variation of degree of certainty for some events.

CONCLUSIONS

Application of definitions by a CRC for a study of HAdV infection and disease is feasible and can provide consistency in the assignment of outcomes. Definitions need further refinement to improve reproducibility and to provide guidance on determining clinical improvement or worsening after initial diagnosis of HAdV infection or disease.

Adjunctive Diagnostic Studies Completed Following Detection of Candidemia in Children: Secondary Analysis of Observed Practice From a Multicenter Cohort Study Conducted by the Pediatric Fungal Network

BACKGROUND

Adjunctive diagnostic studies (aDS) are recommended to identify occult dissemination in patients with candidemia. Patterns of evaluation with aDS across pediatric settings are unknown.

METHODS

Candidemia episodes were included in a secondary analysis of a multicenter comparative effectiveness study that prospectively enrolled participants age 120 days to 17 years with invasive candidiasis (predominantly candidemia) from 2014 to 2017. Ophthalmologic examination (OE), abdominal imaging (AbdImg), echocardiogram, neuroimaging, and lumbar puncture (LP) were performed per clinician discretion. Adjunctive diagnostic studies performance and positive results were determined per episode, within 30 days from candidemia onset. Associations of aDS performance with episode characteristics were evaluated via mixed-effects logistic regression.

RESULTS

In 662 pediatric candidemia episodes, 490 (74%) underwent AbdImg, 450 (68%) OE, 426 (64%) echocardiogram, 160 (24%) neuroimaging, and 76 (11%) LP; performance of each aDS per episode varied across sites up to 16-fold. Longer durations of candidemia were associated with undergoing OE, AbdImg, and echocardiogram. Immunocompromised status (58% of episodes) was associated with undergoing AbdImg (adjusted odds ratio [aOR] 2.38; 95% confidence intervals [95% CI] 1.51-3.74). Intensive care at candidemia onset (30% of episodes) was associated with undergoing echocardiogram (aOR 2.42; 95% CI 1.51-3.88). Among evaluated episodes, positive OE was reported in 15 (3%), AbdImg in 30 (6%), echocardiogram in 14 (3%), neuroimaging in 9 (6%), and LP in 3 (4%).

CONCLUSIONS

Our findings show heterogeneity in practice, with some clinicians performing aDS selectively, potentially influenced by clinical factors. The low frequency of positive results suggests that targeted application of aDS is warranted.

Child and family perceptions of satisfaction with neutropenia management in pediatric acute myeloid leukemia

PURPOSE

Chemotherapy for pediatric acute myeloid leukemia (AML) is very intensive and many, but not all centers, require extended hospitalization until neutrophil recovery. Child and family preferences, beliefs, and experiences around hospitalization have not been systematically assessed.

PATIENTS AND METHODS

We recruited children with AML and their parents from nine pediatric cancer centers across the United States for a qualitative interview about their experiences of neutropenia management. Interviews were analyzed using a conventional content analysis approach.

RESULTS

Of 116 eligible individuals, 86 (74.1%) agreed to participate. Interviews were conducted with 32 children and 54 parents from 57 families. Of these 57 families, 39 were cared for as inpatients and 18 were managed as outpatients. A very high proportion of respondents in both groups reported satisfaction with the discharge management strategy recommended by the treating institution: 86% (57 individuals) of respondents who experienced inpatient management and 85% (17 individuals) of respondents who experienced outpatient management expressed satisfaction. Respondent perceptions associated with satisfaction related to safety (access to emergency interventions, infection risk, close monitoring) and psychosocial concerns (family separation, low morale, social support). Respondents believed it could not be assumed that all children would have the same experience due to varied life circumstances.

CONCLUSION

Children with AML and their parents express a very high degree of satisfaction with the discharge strategy recommended by their treating institution. Respondents saw a nuanced tradeoff between patient safety and psychosocial concerns that was mediated by a child's life circumstances.

Understanding Barriers and Facilitators to Maternal Immunization: A Systematic Narrative Synthesis of the Published Literature

Introduction

Vaccines are being developed against Group B Streptococcus and respiratory syncytial virus. These vaccines are designed to be given to pregnant women to protect infants; thus, their success depends on uptake in this population. Maternal immunization programs have struggled to achieve target coverage rates. This systematic narrative synthesis aims to define the most important barriers and facilitators for maternal immunization and to identify priority areas for future research.

Methods

A search strategy was developed in Medline and adapted according to the requirements of additional search engines. Two reviewers independently reviewed the studies, using pre-specified inclusion and exclusion criteria. Results sections of included studies were coded, and thematic analysis was used to identify prominent themes.

Results

321 studies were included in the final review. Most studies came from North America (37%), Europe (26%) or East Asia, Australia and New Zealand (22%). Low-and middle-income countries were under-represented. Five percent of studies came from Sub-Saharan Africa, and 2% came from South Asia. The prominent factors impacting maternal immunization were provider recommendation, perceived risks and benefits of maternal vaccines for the infant, race, birthplace, and access to healthcare. Few studies explored reasons behind racial and socioeconomic disparities in maternal immunization rates.

Discussion

A strong provider recommendation, equitable access to prenatal care and messaging that focuses on vaccine safety and infant benefits emerged as the key components for optimising vaccine uptake among pregnant women. Research among healthcare providers, minority groups and in low- and-middle-income countries was lacking. In anticipation of the expansion of maternal immunization programmes, focused research is needed to address these gaps and inform a successful public health strategy.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10995-022-03508-0.

Multicenter Prospective Study of Biomarkers for Diagnosis of Invasive Candidiasis in Children and Adolescents

BACKGROUND

Diagnosis of invasive candidiasis (IC) relies on insensitive cultures; the relative utility of fungal biomarkers in children is unclear.

METHODS

This multinational observational cohort study enrolled patients aged >120 days and <18 years with concern for IC from 1 January 2015 to 26 September 2019 at 25 centers. Blood collected at onset of symptoms was tested using T2Candida, Fungitell (1→3)-β-D-glucan, Platelia Candida Antigen (Ag) Plus, and Platelia Candida Antibody (Ab) Plus assays. Operating characteristics were determined for each biomarker, and assays meeting a defined threshold considered in combination. Sterile site cultures were the reference standard.

RESULTS

Five hundred participants were enrolled at 22 centers in 3 countries, and IC was diagnosed in 13 (2.6%). Thirteen additional blood specimens were collected and successfully spiked with Candida species, to achieve a 5.0% event rate. Valid T2Candida, Fungitell, Platelia Candida Ag Plus, and Platelia Candida Ab Plus assay results were available for 438, 467, 473, and 473 specimens, respectively. Operating characteristics for T2Candida were most optimal for detecting IC due to any Candida species, with results as follows: sensitivity, 80.0% (95% confidence interval, 59.3%-93.2%), specificity 97.1% (95.0%-98.5%), positive predictive value, 62.5% (43.7%-78.9%), and negative predictive value, 98.8% (97.2%-99.6%). Only T2Candida and Platelia Candida Ag Plus assays met the threshold for combination testing. Positive result for either yielded the following results: sensitivity, 86.4% (95% confidence interval, 65.1%- 97.1%); specificity, 94.7% (92.0%-96.7%); positive predictive value, 47.5% (31.5%-63.9%); and negative predictive value, 99.2% (97.7%-99.8%).

CONCLUSIONS

T2Candida alone or in combination with Platelia Candida Ag Plus may be beneficial for rapid detection of Candida species in children with concern for IC.

CLINICAL TRIALS REGISTRATION

NCT02220790.

The banning of sportsmen and women who fail drug tests is unjustifiable

The use of performance enhancing drugs among elite athletes has been in the headlines recently, particularly with Lance Armstrong's fall from grace and his admission about widespread doping. Many argue that the use of drugs confers an unfair advantage and is ultimately dangerous to the health of the athletes. Others, like Professor Shuster, argue that the use of drugs is no different from other techniques employed by athletes to boost their performance: swimmers shaving their body hair; skiers wearing sleek body armour; archers and shooters having laser eye surgery to improve their accuracy. Professor Shuster puts forward the provocative argument that since 'there is no acceptable proof (that) drugs improve competitive performance and their use is no different from accepted sports practice, banning them is wrong and immoral.' JW Devine argues the other side, that the use of performance enhancing drugs poses a 'significant risk to the health of athletes' and perhaps more importantly, 'threatens to undermine the very purpose of sport' by disrupting the 'balance of excellences'.

Fingerprint maintenance, a new dermatoglyphic mechanism

BACKGROUND

Although dermatoglyphic structure has been mechanistically related to fingerprint formation, a separate mechanism for fingerprint maintenance must exist or prints would be lost by friction.

OBJECTIVES

To test this prediction and study its operation.

METHODS

Palmar and plantar prints were studied visually and by silicone rubber impressions after surface removal by abrasives, scalpel and adhesive stripping, using surface staining to stage surface loss.

RESULTS

All depths and methods of surface removal left the print ridges intact visually and in silicone rubber impressions. When abrasion was applied only to ridge surfaces, keratinocytes were lost concomitantly in the troughs between them, leaving ridge structure intact. When palmar or plantar stratum corneum was cleaved or peeled apart, the separated layer followed the undulating ridges and troughs, thus maintaining the normal print pattern.

CONCLUSIONS

A new mechanism of fingerprint maintenance was predicted theoretically and confirmed experimentally. It is achieved by an organization of the print corneum which ensures its continuous separation over the whole of the undulating print surface, even when friction is applied only to the tips of the ridges; the preferred route of separation of print keratinocytes runs up and down the print ridges and troughs and thereby maintains them, and is presumably ordered by predominantly horizontal intercellular attachments between print keratinocytes. The reason print maintenance has been missed until now may be that dermatoglyphic researchers have little interest in fingerprint disguise, while those who are interested in disguise have little interest in research.

Melanoma epidemic: a midsummer night's dream?

BACKGROUND

The reported incidence of melanoma has greatly increased and this has been attributed to ultraviolet exposure.

OBJECTIVES

We considered the possibility that the increase was an artefact caused by diagnostic drift.

METHODS

We tested this by analysing the histological diagnosis, mortality and incidence of all lesions reported as melanomas in East Anglia between 1991 and 2004.

RESULTS

There were 3971 melanomas in all, and their annual incidence increased from 9.39 to 13.91 cases per 100,000 per year during the period studied. This increased incidence was almost entirely due to minimal, stage 1 disease. There was no change in the combined incidence of the other stages of the disease, and the overall mortality only increased from 2.16 to 2.54 cases per 100,000 per year.

CONCLUSIONS

We therefore conclude that the large increase in reported incidence is likely to be due to diagnostic drift which classifies benign lesions as stage 1 melanoma. This conclusion could be confirmed by direct histological comparison of contemporary and past histological samples. The distribution of the lesions reported did not correspond to the sites of lesions caused by solar exposure. These findings should lead to a reconsideration of the treatment of 'early' lesions, a search for better diagnostic methods to distinguish them from truly malignant melanomas, re-evaluation of the role of ultraviolet radiation and recommendations for protection from it, as well as the need for a new direction in the search for the cause of melanoma.

The nature and consequence of Karl Marx's skin disease

From an analysis of the original correspondence, it has been possible to establish that Karl Marx's incapacitating skin disease was hidradenitis suppurativa, not 'boils' as was universally assumed at the time and since; the psychological effect of this illness on the man and his work appears to have been considerable.

Distribution of hyaluronan in human endometrium across the menstrual cycle. Implications for implantation and menstruation

Hyaluronan is a molecule with many known roles in cellular physiology and is often associated with tissue remodeling. The human endometrium undergoes dramatic remodeling during the course of the normal menstrual cycle but its regulation is not well understood. This study examined the levels of deposition of hyaluronan in human cycling endometrium by histochemical localization, using a highly specific hyaluronan-binding peptide. This was facilitated by avoiding conventional formalin fixation, which results in serious loss of the water-soluble hyaluronan. Peaks of hyaluronan deposition were observed in the stromal compartment during the mid-proliferative (days 5-10) and the mid-secretory phase (days 19-23) of the cycle. In physiological terms, the first phase corresponds to the time of rapid cellular proliferation of undifferentiated cells, whereas the second phase coincides with the time when the implantation of the conceptus would be initiated in a fertile cycle. By the time menstruation starts, very little hyaluronan remains in the stroma. In contrast with the stromal staining, hyaluronan deposition around blood vessels was constant throughout the cycle. The dramatic changes in hyaluronan deposition and their correlation with the cyclic growth and remodeling in the human endometrium suggest a major role for hyaluronan in the physiology of this tissue.

Hyaluronidase can modulate expression of CD44

CD44 is a family of transmembrane glycoproteins with multiple isoforms generated by alternative exon splicing of a single gene. CD44 and its variants are expressed on a wide variety of cells including cancer cells. The mechanisms by which splice variant exons are selected are unknown. The presence of hyaluronan in the environment of the cell appears to influence that selection process. The expression of particular splice variants of CD44 as well as the simultaneous presence of hyaluronan is important for motility, invasion, and the metastatic spread of some tumors. The influence of hyaluronidase digestion on the expression of CD44 in human cancer cell lines was examined. CD44 isoforms containing alternatively spliced exons were sensitive to hyaluronidase digestion in all lines examined, but differences between cell lines were observed. Expression of CD44s, the standard form, was resistant to digestion in two of three cell lines. A tentative model was formulated proposing that CD44 isoforms containing splice variants are unstable, requiring the continuous presence of ligand for expression. CD44s is relatively more stable, not requiring the continuous presence of hyaluronan. Additionally, a number of new CD44 variant isoforms, not previously observed, were identified.

Reduced hyaluronan in keloid tissue and cultured keloid fibroblasts

Extracellular matrix hyaluronan is prominent during wound healing, appearing at elevated levels early in the repair process. It is prevalent throughout the course of fetal wound healing, which is scar-free, but decreases late in adult wound repair, that is often marked by scarring. To determine whether aberrant hyaluronan metabolism is associated with the excessive scarring that characterizes keloids, cultured fibroblasts derived from keloids and from the dermis of normal human skin and scar were compared. Levels of hyaluronan in 48 h conditioned media of keloid-derived cultures were significantly lower than in cultures of normal skin and scar fibroblasts. Profiles of hyaluronan polymer size were comparable in these two cell types, suggesting that excessive hyaluronan degradation was not involved. Hydrocortisone decreased hyaluronan levels approximately 70% in the conditioned media of both keloid and normal fibroblasts. Diminished hyaluronan accumulation in keloid-derived cells compared with normal fibroblasts was also observed in an in vitro wound healing model. Histolocalization of hyaluronan in keloids, normal skin, and scar samples confirmed the biochemical observations that the dermis of keloids, which comprises most of the scar tissue, contained markedly diminished levels of hyaluronan. Alterations in hyaluronan in the epidermis overlying keloids, however, were also observed. A modest increase in hyaluronan staining intensity was observed in the epidermis of keloids, as well as changes in the patterns of distribution within the epidermis, compared with that in normal skin and scar. Increased hyaluronan was present in the granular and spinous layers of the keloid epidermis Abnormalities are present apparently in both the overlying epidermis as well as in the dermis of keloids. Aberrations in signaling between keloid stroma and keloid epidermis may underlie abnormalities that contribute to the excessive fibrosis characteristic of these lesions.

Topical hyaluronidase decreases hyaluronic acid and CD44 in human skin and in reconstituted human epidermis: evidence that hyaluronidase can permeate the stratum corneum

Hyaluronic acid (HA), a high molecular weight glycosaminoglycan of the extracellular matrix involved in growth, inflammation and wound healing, also contributes to the hydration and plastic properties of skin. Several drug and cosmetic formulations contain HA. We have initiated investigations that explore whether it is possible, by topical application, to modulate endogenous HA levels in skin. We developed a model epidermal culture system that exhibited a differentiated stratum corneum, and expressed HA and the HA receptor CD44, in a pattern similar to that observed in intact skin. Such in vitro skin equivalents are useful models for investigating the effect of topical drugs. HA and bacterial hyaluronidase were applied to the in vitro skin equivalent and to human skin. Their effects on endogenous HA and CD44 expression were examined using histochemical analysis. Topical HA treatment had no significant effect on HA or CD44 expression in either system. However, hyaluronidase decreased HA and CD44 expression in a dose-dependent manner in both the epidermal culture system and in skin. Apparently, HA is not able to permeate the epidermal culture system or human skin to a significant degree, but bacterial hyaluronidase does permeate both human skin and the culture system, depleting HA and decreasing CD44 expression. These effects were more prominent in the dermal than in the epidermal layers, suggesting that marked differences in HA metabolism exist in these two skin compartments. The ability of hyaluronidase to permeate the stratum corneum suggests that topical application may, additionally, be useful as a clinical modality.

Induction of resistance to diabetes in non-obese diabetic mice by targeting CD44 with a specific monoclonal antibody

Inflammatory destruction of insulin-producing beta cells in the pancreatic islets is the hallmark of insulin-dependent diabetes mellitus, a spontaneous autoimmune disease of non-obese diabetic mice resembling human juvenile (type I) diabetes. Histochemical analysis of diabetic pancreata revealed that mononuclear cells infiltrating the islets and causing autoimmune insulitis, as well as local islet cells, express the CD44 receptor; hyaluronic acid, the principal ligand of CD44, is detected in the islet periphery and islet endothelium. Injection of anti-CD44 mAb 1 hr before cell transfer of diabetogenic splenocytes and subsequently on alternate days for 4 weeks induced considerable resistance to diabetes in recipient mice, reflected by reduced insulitis. Contact sensitivity to oxazolone was not influenced by this treatment. A similar antidiabetic effect was observed even when the anti-CD44 mAb administration was initiated at the time of disease onset: i.e., 4-7 weeks after cell transfer. Administration of the enzyme hyaluronidase also induced appreciable resistance to insulin-dependent diabetes mellitus, suggesting that the CD44-hyaluronic acid interaction is involved in the development of the disease. These findings demonstrate that CD44-positive inflammatory cells may be a potential therapeutic target in insulin-dependent diabetes.

Antipruritic action of thalidomide

The effect of thalidomide on itch was studied in 11 patients with chronic pruritus from psoriasis, eczema, nodular prurigo, senile pruritus and primary biliary cirrhosis. Itch, assessed subjectively by the patients on a 10 cm line and measured objectively as nocturnal scratch movement, was decreased by thalidomide 200 mg on the 2 nights it was given. There was no improvement in the underlying disorders and it is concluded that thalidomide is a primary antipruritic agent. The patients all became drowsy and it seems likely that, as with most other antipruritic agents, the antipruritic action of thalidomide results from a central depressant effect. The primary antipruritic effect of thalidomide should now be assessed therapeutically.

Hyaluronan and CD44 expression in minor salivary gland tumors

OBJECTIVES

Hyaluronan (HA) and CD44 are most likely associated with tumor invasion and metastasis. Malignancies with different degrees of aggressiveness may express different levels and patterns of HA and CD44. The aim of this project was to examine the distribution of HA and CD44 in minor salivary gland tumors to determine if staining could be correlated with biologic behavior or tumor type.

MATERIALS AND METHODS

Biotinylated hyaluronan binding protein as a probe for HA and monoclonal antibodies specific for CD44 were used to stain classic examples of the five most commonly encountered minor salivary gland tumors: monomorphic adenomas, pleomorphic adenomas, polymorphous low grade adenocarcinomas, mucoepidermoid carcinomas, and adenoid cystic carcinomas.

RESULTS

Tumor cells of monomorphic adenomas were negative for both HA and CD44, and tumor capsules were intensely HA-positive. Pleomorphic adenomas exhibited HA and CD44 positivity in both mesenchymal and epithelial components, and HA in capsular tissues. All malignant salivary gland tumors expressed similar intense HA in tumor stroma. HA staining was more intense in stroma than in parenchymal cells. Tumor cells of most adenoid cystic carcinomas were HA-positive, while most polymorphous low grade adenocarcinomas were HA-negative. HA was uniformly distributed throughout supporting stroma of high and low grade malignancies, except for two polymorphous low grade adenocarcinomas (PLGAs) in which HA was more intense at the invading edge of the tumors. CD44 expression was seen only in tumor cells (not stroma) of malignancies, and was of similar intensity in both low and high grade tumors.

CONCLUSIONS

Differences in the expression of HA and CD44 among different types of salivary gland tumors were noted. These findings, however, could not be correlated with known biologic behaviors of the tumor groups studied. Immunohistochemical staining of salivary gland tumors for HA and CD44 may be useful in separating monomorphic adenoma, polymorphous low grade adenocarcinoma and adenoid cystic carcinoma, lesions that may be difficult to distinguish with routine light microscopy.

Onychomycosis: making sense of the assessment of anti-fungal drugs

After years of therapeutic triviality, we now have drugs with a major effect on onychomycosis, and, paradoxically, their very success will lead to the development of more such drugs. This note is concerned with improving their assessment by rationalizing the way in which efficacy is measured. The need for this will be apparent to anyone who has had to review studies of antifungal drugs for onychomycosis, especially those done for drug registration. To the more fortunate others, who can use these drugs without having to suffer the tedious analyses of "evidence", it is necessary only to say that the methodology for the assessment of response is a muddle, illogical in almost all its aspects. I will therefore consider all the procedures involved, examine their weaknesses and suggest some simple improvements. Do not confuse my purpose: this is not a review, nor an "overview", its duplicitous offspring; while I base my case on an analysis (and increasingly desparing reading) of the literature, I do not intend to anatomize it.

Hyaluronan is a prerequisite for ductal branching morphogenesis

Hyaluronan, a macromolecular carbohydrate polymer of the extracellular matrix is prominent early in embryogenesis, coinciding with rapid tissue growth. CD44, the predominant receptor for hyaluronan on vertebrate cells, is a variably expressed transmembrane glycoprotein. Mouse anterior prostate glands obtained at various postnatal time points were examined for the expression of hyaluronan and CD44. Reverse transcriptase polymerase chain reaction analysis was used to map the temporal regulation of specific CD44 variant isoforms. In each age group, hyaluronan was localized exclusively in the stromal matrix. Hyaluronan was greatly reduced in the later ages and was entirely absent around the developmentally quiescent proximal regions of the ducts. Early in prostate development, CD44 was prominent in the mesenchyme. However, in the later phases, CD44 expression became associated with membranes of epithelial cells. The role of hyaluronan-CD44 interactions in ductal branching morphogenesis was studied by serum-free organ culture of mouse anterior prostate. In the presence of optimal levels of testosterone, the organs underwent ductal branching morphogenesis. Treatment with either neutralizing anti-CD44 antibodies, hyaluronan hexasaccharides or the enzyme hyaluronidase inhibited androgen-stimulated ductal branching morphogenesis. These results are suggestive of the significant role played by hyaluronan-CD44 interactions in mediating androgen-induced prostatic growth and morphogenesis.

Dermatoglyphics in Darier's disease

Palmar and fingerprints were taken from 70 patients with Darier's disease and 409 normal controls. The dermatoglyphic characteristics of each group were determined and comparisons were made between them. Dermatoglyphic abnormalities were found; some confirmed previous findings and some were novel, but they are too small in degree and frequency to be of use diagnostically.

Patterns of hyaluronan staining are modified by fixation techniques

The apparent intensity of hyaluronan (HA) staining in tissue sections can vary as a function of fixation techniques. We examined the histochemical distribution of HA in normal human skin using an HA-specific binding peptide derived from bovine nasal cartilage. The HA, particularly in the dermis, was best preserved in sections fixed in 10% acid-formalin with 70% ethanol. In contrast, sections fixed in the routine 10% neutral-buffered formalin had a much weaker intensity of HA staining. Furthermore, acid-formalin/ethanol-fixed sections retained much of their apparent HA after incubation with saline, in contrast to the neutral formalin-fixed sections, in which most of the stainable HA was lost. Such marked differences in staining intensity were not observed in slides stained with Alcian blue, a procedure presumed to stain HA as well as other glycosaminoglycans. Staining using the HA binding peptide was entirely absent when sections were first preincubated in hyaluronidase, whereas similar Alcian blue-stained sections retained most of their staining intensity. Caution should be exercised in evaluating the distribution of HA in tissues using the HA binding peptide, particularly when different fixation techniques among several laboratories are being compared. In addition, the ability to evaluate the HA content of tissues using Alcian blue staining should be reconsidered. The sulfated glycosaminolglycans of the "ground substance" appear to be the predominant substrates for Alcian blue.

Duct disruption, a new explanation of miliaria

From argument and a few personal observations, the hypothesis has crystallised that the miliaria commonly occurring in unacclimatised Caucasians visiting hot climates is caused by exposure to ultraviolet irradiation, by an effect on the cells of the upper epidermis, which eventually allows a split to develop between them and the new stratum corneum that grows up beneath, into which sweat from the disrupted ducts can collect as microcysts. This dehiscence is the probable explanation of sunburn peeling and photo-onycholysis. It is concluded that duct disruption, not blockage or dysfunction, is the immediate cause of the miliarias.

Human vitreous hyaluronidase: isolation and characterization

PURPOSE

Hyaluronic acid (HA) is the predominant glycosaminoglycan (GAG) of the human vitreous. Interaction of this HA with vitreous collagen is important for maintaining gel structure. The mechanism of HA homeostasis in the vitreous is incompletely understood. The aim of this study was to determine whether hyaluronidase, an endoglycosidase that degrades HA, was present in human vitreous.

METHODS

Vitreous samples were collected from post-mortem eye bank specimens and from non-hemorrhagic, non-inflamed biopsy specimens. Vitreous hyaluronidase was purified by a series of column chromatographic steps, and its activity was measured by an ELISA-like assay and by substrate gel electrophoresis through and HA-impregnated gel. The purified hyaluronidase was also analyzed by SDS-polyacrylamide gel electrophoresis (SDS-PAGE) and by Western blotting.

RESULTS

Hyaluronidase activity was detected in vitreous samples from both post-mortem and biopsy specimens. The enzyme was most active at acid pH, but demonstrated significant activity at neutral pH. The partially purified enzyme migrated as a 59 kDa protein on SDS-PAGE, and a single band on Western blots.

CONCLUSIONS

Hyaluronidase is present in the human vitreous. Thus, hyaluronidase may be involved in HA catabolism in the vitreous and may play a role in determining its gel structure.

Patch testing with a combination of unrelated allergens: a new strategy

A simplified method of patch testing was designed, in which several totally unrelated allergens were combined in each patch. The method was evaluated by double blind comparison of responses to 17 standard allergens applied individually as 17 conventional patch tests, and as two different sets of five patches each containing combinations of three of four allergens per patch, in 137 patients under investigation for contact allergic dermatitis. There were 89 positive responses to conventional patch testing with separate allergens and 94 and 86 positives to the two different combinations of the same allergens. Concordance of positive reactions to the two combinations was 80% and there were no irritant reactions. Conventional testing detected 70 and 74% of reactions to combination patches 1 and 2 and combination patches 1 and 2 detected 80 and 79% of the reactions to conventional testing. The combinations detected clinically relevant sensitivities not found by conventional testing. Thus, combination patch testing appears to give consistent and reliable results; its use would reduce the number of patches and increase the diagnostic yield for the specialist and permit preliminary screening by the general practitioner.

Hyaluronan, CD44 and its variant exons in human trophoblast invasion and placental angiogenesis

Both hyaluronan and one of its receptors, CD44, can be demonstrated in the early human conceptus and in placental stroma. The variants of CD44 resulting from variable exon splicing are found in metastasizing human malignancies and are also involved in hyaluronan uptake and degradation. The resulting hyaluronan fragments are known to be highly angiogenic. We postulated that the self-limited process of trophoblast invasion of the uterine decidua results in part from the strategy of alternative splicing of CD44, similar to that used by invasive cancer cells in the course of metastatic spread and possibly angiogenesis. Monoclonal antibodies specific for CD44s and for an exon expressed during metastatic tumour progression, CD44v7, were used to examine this hypothesis. In this study we found human trophoblasts, for the first time, to express CD44. Intermediate trophoblasts of first and second trimester exhibited the standard form of CD44 while extravillous trophoblasts, which are responsible for the invading characteristics of the placenta, were positive for the alternatively spliced form, the CD44v7-8. Moreover, in the case of placenta accreta there was a prominent membrane staining of the trophoblasts that were embedded in the fibrin layer over the myometrium. The highly metastatic choriocarcinoma cells also expressed CD44v7-8. We propose, therefore, that the invading trophoblasts utilize the alternatively splicing machinery. These cells retain their invasive capabilities through the permissive ECM by carrying the CD44v7-8 isoform, which binds weakly to hyaluronan and thus prevents it from being degraded by intracellular hyaluronidase.