Giant axonal neuropathy (GAN): case report and two novel mutations in the gigaxonin gene

Giant axonal neuropathy (GAN) is an autosomal recessive neurologic disorder clinically characterized by a severe polyneuropathy, CNS abnormalities, and characteristic tightly curled hair. Recently, mutations in the gigaxonin gene have been identified as the underlying genetic defect. The authors report two novel mutations confirming that GAN is caused by mutations in the gigaxonin gene and raise the question whether some mutations may cause a mild subclinical neuropathy.

A randomized, controlled pilot study of the safety and efficacy of 4% icodextrin solution in the reduction of adhesions following laparoscopic gynaecological surgery

BACKGROUND

Adhesion-related readmissions are frequent sequelae to gynaecological surgery. Attempts to prevent adhesions by separating healing peritoneal surfaces include site-specific barriers and hydroflotation by instilled solutions. Rapid absorption limits the effectiveness of solutions such as Ringer's lactated saline (RLS). This pilot study assessed the safety, tolerability and preliminary effectiveness of a non-viscous, iso-osmolar solution of 4% icodextrin, an alpha-1,4 glucose polymer with prolonged intraperitoneal residence, in reducing adhesions after laparoscopic gynaecological surgery.

METHODS

Women aged > or = 18 years, requiring laparoscopic adnexal surgery (n = 62), were entered into a randomized, open-label, assessor-blinded, multicentre study to compare 4% icodextrin with RLS. Treatments were coded in blocks of four with equal randomization to each group, and pre-allocated to consecutively numbered patients. At least 100 ml per 30 min was used for intra-operative lavage, with 1 l instilled post-operatively. Per protocol analysis included all eligible patients (n = 53); reformation analysis required one or more baseline adhesion (n = 42). Incidence, extent and severity of post-operative adhesions were assessed at second-look laparoscopy after 6-12 weeks. Procedures were video-taped for third party, blinded assessment.

RESULTS

Safety and tolerability (laboratory variables, adverse events, clinical follow-up) were good with no difference between treatments. A shift analysis of incidence-ranked adhesions (n = 53) showed apparent improvements in more patients with icodextrin than RLS (37 versus 15%; not significant). Adhesion score reduction (n = 42) was more frequent in icodextrin- than RLS-treated patients: incidence (52 versus 32%), extent (52 versus 47%), and severity (65 versus 37%). Despite greater baseline adhesions, median reformation was less after icodextrin (24%) than RLS (60%). The pilot study group sizes were not powered for statistical significance.

CONCLUSIONS

In this preliminary study, 4% icodextrin lavage plus instillation was well tolerated and reduced adhesion formation and reformation following laparoscopic gynaecological surgery. A Phase III pivotal study is currently in progress.

DNA microarray analysis of differential gene expression of 6-year-old rat neural striatal progenitor cells during early differentiation

EGF-responsive striatal progenitor cells from rat brain have been maintained in culture in the form of neurospheres for six years without exhausting their renewal capacity. The events surrounding differentiation of stem cells in the brain after a long progenitorship remain a mystery. Using DNA microarray analysis we investigated differential gene expression, comparing progenitor cells in their neurosphere state with the cells 24 hours after induction of differentiation. Eighty-one genes showed increased expression in the differentiated condition. Genes associated with cellular growth, neurite outgrowth, and synaptogenesis were activated, including both anti-apoptotic and pro-apoptotic genes. Two transmitter- related genes, acetylcholine receptor-beta and glutamate receptor-beta-unit were also elevated-, these genes not only fit the profile of early neural development, but also reflect the characteristics of striatal neurons. In addition, there are approximately 30 expressed sequence tags (ES7) increased during neural differentiation. Forty-seven genes showed decreased expression; half of them are known genes related to the cell cycle, cell adhesion, transcription, and signaling. Tbe signaling and cell cycle genes may be responsible for the life-long self-renewal. These data demonstrate for the first time that life-long quiescent stem cells retain the potential to become activated and develop into specific types of brain cells. The six-year long-term neural stem cells are an excellent model for studying developmental neurobiological processes and aging.

Co-existent cutaneous cryptococcosis of the forearm and cutaneous alternariosis of the leg in patient with metastatic thymoma

BACKGROUND

Cryptococcosis and alternariosis are rare opportunistic infections often observed in immunocompromised patients. Because Cryptococcus and Alternaria are ubiquitous fungi found in soil, the presence of fungi in the dermis has to be observed on histological examination to confirm a real cutaneous, invasive, infection.

PATIENT

We report the first case of concomitant cutaneous cryptococcosis and cutaneous alternariosis, in an immunocompromised patient treated for a metastatic thymoma.

CONCLUSION

This observation underlines the fact that the possible co-existence of several rare infections in immunocompromised patients should take into consideration pathogen identification in order to adapt the therapy to individual patient requirements.

[Chronic eczematiform eruption in the elderly]

INTRODUCTION

Eczematiform eruptions in the elderly represent a relatively frequent motive for consultation and may lead to repeated hospitalization. Their etiologic diagnosis is often difficult and explains the frequent relapses. The frequent relapses can be explained by the difficulty in determining their etiologic diagnosis. The aims of this study were: 1) to specify the evolving characteristics of these eruptions in elderly patients and 2) determine their etiology.

PATIENTS AND METHODS

The inclusion criteria in this retrospective study were: patients aged over 65 at the time of diagnosis, presenting with extensive eczematiform eruption (> 20 p. 100 of body surface) and lasting for more than one month. Eczema on stasis dermatitis of the lower limbs and generalized contact eczema were excluded. Eighty-three patients followed between January 1990 and January 1999 were included. The clinical, biological, histological and evolving characteristics were analyzed.

RESULTS

Mean age of patients was 77 +/- 8 years and the male female sex ratio was 2.4. Patients received a mean of 4.0 +/- 2.6 drugs/patient, consisting essentially of cardiovascular and psychotropic agents. The cutaneous eruption had evolved a mean of 12.5 months (1 to 48 months) before diagnosis. Eczema was pruriginous in 92 p. 100 of cases. Frequent relapses were observed in 68 p. 100 of cases. Precise etiologic diagnosis was retained in 48 patients (58 p. 100). This was disseminated contact eczema (n=19), lymphoma cutis (n=10), atopic eczema (n=7), scabies acariasis (n=6) and pemphigoid (n=6). No etiologic diagnosis was retained in the remaining 35 patients (42 p. 100). Comparison of the characteristics in the 2 groups showed excessive consummation of medicinal products (p=0.024), predominant eruption of sun-exposed areas (p=0.004) and a greater frequency of histological images of keratinocyte necrosis (p=0.0072) in patients presenting eczematiform eruptions of unknown etiology.

DISCUSSION

These observations suggest the eventual responsibility of medicinal products in the occurrence of certain extensive and chronic eczematiform eruptions in the elderly. However, the delays of imputability of various causal drugs were often longer than those currently admitted for toxidermia, and the withdrawal of potentially imputable agents rarely led to spectacular improvement in the lesions. A case test report is in progress to specify this hypothesis.

An investigation of condom use by frequency of sex

OBJECTIVES

To examine the association between condom use and frequency of sex across sexual partner types.

METHODS

Data were collected from African American drug users residing in Washington, DC. Participants were asked to provide the first name of the last three partners with whom they had had vaginal sex, to define the type of relationship, the number of times they had had vaginal sex in the last 30 days with each partner, and whether they had used a condom during their last sexual encounter with each partner. Condom use was examined by frequency of sex in the past 30 days controlling for partner type.

RESULTS

Frequency of sexual encounters varied by partner type. The largest number of sexual encounters was with casual partners, followed by commercial and primary partners, respectively. Within partner types, participants had sex most frequently with primary partners. Condom use was lowest within primary partner relationships. Regardless of partner type, condom use varied consistently depending on the frequency of sex with the same partner.

CONCLUSIONS

Condom use is related to the frequency of sex between partners when partner type is controlled. The association between frequency of sex and condom use is independent of partner type, suggesting that partner type may become less influential in determining condom use as the frequency of sex increases. This finding suggests that contextual factors determining condom use go beyond partner type designations and include other relationship variables.

Regulation of Schwann cell proliferation and apoptosis in PMP22-deficient mice and mouse models of Charcot-Marie-Tooth disease type 1A

Charcot-Marie-Tooth disease type 1A (CMT1A) is caused by an increased dosage of the peripheral myelin protein 22 (PMP22) gene or by point mutations affecting the same gene. Based on in vitro data, PMP22 might be involved, besides in its proven role in the regulation of myelination and myelin maintenance, in the control of Schwann cell proliferation and programmed cell death. In this report, we have used mice lacking PMP22 and mouse models for CMT1A to analyse Schwann cell proliferation and apoptosis in vivo during postnatal sciatic nerve development. Our results show that there is no significant change in the number of Schwann cells at postnatal day 1 in the analysed PMP22 mutants compared with the corresponding wild-type animals. Furthermore, the rate of proliferation also was not changed at this early developmental time point. In contrast, cell density and proliferation rates were increased, albeit with different kinetics, in all PMP22 mutants later in development. The increase in proliferation is paralleled by a higher number of apoptotic Schwann cells found in the nerves. Thus, increased Schwann cell proliferation and apoptosis, but only in later development and in adults, are hallmarks of PMP22 mutant mice, regardless of whether increased or decreased PMP22 gene dosage or point mutations affecting the PMP22 gene are responsible for the resulting demyelinating, dysmyelinating or amyelinating phenotypes.

Fat emulsification measured using NMR transverse relaxation

This paper presents a novel method of measuring the droplet size in oil-in-water emulsions. It is based on changes in the NMR transverse relaxation rate due to the effect of microscopic magnetic susceptibility differences between fat droplets and the surrounding water. The longitudinal and transverse relaxation rates of a series of emulsions with constant oil volume fraction and five different mean droplet sizes, in the range 0.4-20.9 microm, were measured in vitro at 37 degrees C using EPI. While the longitudinal relaxation rate 1/T(1) did not change significantly, 1/T(2) was observed to increase with mean droplet size. The measured changes in 1/T(2) were found to be in good agreement with results predicted from proton random walk simulations, and were also consistent with analytical solutions based on an outer sphere relaxation model. Measurements of 1/T(2) on emulsions with a higher oil volume fraction, and on emulsions of a fixed size where the water phase was doped with gadolinium to modulate the susceptibility difference between the phases, also showed the predicted behavior. As part of this study the susceptibility difference between olive oil and water was measured to be 1.55 ppm.

Disease mechanisms and potential therapeutic strategies in Charcot-Marie-Tooth disease

Until 10 years ago, the genetic basis of Charcot-Marie-Tooth (CMT) disease was largely unknown. With the finding of an intrachromosomal duplication on chromosome 17 in 1991, associated with the most commonly found subtype CMT1A, and the discovery of a point mutation in the peripheral myelin protein-22 (pmp22) gene in the Trembler mouse in 1992, the groundwork was laid down for a novel chapter in the elucidation of the molecular basis of this large group of peripheral neuropathies. In the meantime, several different genes have been found to be associated with different forms of demyelinating and axonal forms of CMT. In this review, we will summarize what is known today about the genetics of this group of disease which constitute the most common known monogenetic disorder affecting the nervous system in man, the animal models that have been generated, and what we have learned about the underlying disease mechanisms. Furthermore, we will review how this gain of knowledge about CMT may open new avenues to the development of novel treatment strategies.

Antral motility measurements by magnetic resonance imaging

Magnetic resonance imaging has been recently proposed as a promising, noninvasive technique to assess the motility of the gastric antrum. However, so far the reproducibility and dependence on test meal composition has not been evaluated. In this study, snapshot echo-planar magnetic resonance imaging was used to measure the frequency, propagation speed and percentage occlusion of antral contractions in 28 healthy volunteers. They were fed either liquid (n=12), mixed liquid/solid (n=8) or mixed viscous/solid (n=8) nutrient (1350 kJ) test meals, and a total of 208 motility measurements were performed. No effect of meal type on antral motility parameters was observed. Antral contraction frequency was 3.0 +/- 0.2 min(-1) (mean +/- SD, n=164), propagation speed was 1.6 +/- 0.2 mm s(-1) (n=164) and the percentage occlusion was 58 +/- 14% (n=76). Overall, 21% of measurements did not provide useful antral motility data, because, in the supine position, the antrum was not filled by the test meal. Simple methods to overcome this and reduce scanning time to a minimum are proposed. The results show that the noninvasive magnetic resonance imaging evaluation of antral motility is accurate and reproducible and has potential to become a standard tool for such investigations.

Hereditary Neuralgic Amyotrophy (HNA) is genetically heterogeneous

Hereditary Neuralgic Amyotrophy (HNA) is an autosomal dominantly inherited recurrent focal neuropathy affecting mainly the brachial plexus. Linkage to markers on chromosome 17q25 was found in 1996 and subsequent reports confirmed linkage of HNA to this locus. Recently a family with a chronic undulating rather than remitting-relapsing clinical course of HNA was described by a Dutch group. This family did not have linkage to the 17q25 locus. Here we describe for the first time clinically and genetically two families with classic remitting-relapsing HNA that are not linked to the previously described HNA locus on chromosome 17q25. These results demonstrate that clinically homogeneous classical HNA is genetically heterogeneous.

A study of infertility treatment and melanoma

This study examined the possible association between melanoma and exposure to fertility drugs, specifically clomiphene citrate, human menopausal gonadotrophin (HMG) and human chorionic gonadotrophin (HCG). A cohort of 3186 women who attended a fertility clinic between 1 January 1980 and 31 December 1990 was studied; by January 1996, 14 women had been diagnosed with primary melanoma. Details of fertility treatment were extracted from the clinical records. The incidence of melanoma in the cohort resembled that of the female Queensland population (standardized incidence ratio = 0.89, 95% confidence interval [CI] = 0.54-1.48). Exposure to clomiphene citrate, HMG or HCG did not affect the incidence of melanoma. Women with infertile partners who were treated with fertility drugs were at increased risk of melanoma (odds ratio [OR] = 3.17, 95% CI = 1.01-9.98). Compared with women exposed only to clomiphene citrate and HMG, a lower incidence of melanoma was observed among those who received HCG as well (OR = 0.10, 95% CI = 0.02-0.42). Women exposed to two or more cycles of either clomiphene citrate (OR = 0.27, 95% CI = 0.08-0.94) or HMG (OR = 0.23, 95% CI = 0.07-0.84) had a significant reduction in melanoma risk compared with women exposed to no or one cycle. In summary, a woman's infertility per se was not found to be associated with melanoma, while exposure to fertility drugs was positively associated with melanoma in women with infertile partners and negatively associated in women with low doses of fertility drugs.

Haemodynamic, invasive and echocardiographic monitoring in the hypertensive parturient

AIM

To determine the clinical usefulness of invasive and non-invasive haemodynamic assessment in pre-eclampsia.

METHOD

A systematic review of the literature was undertaken, using a MEDLINE electronic search using a combination of MESH headings and textwords. Over 1500 abstracts were perused; we obtained 156 full papers that were related to the subject matter. Of the full papers, 55 yielded relevant information. Hand-searching the reference lists of the retrieved papers completed the search.

RESULTS

There are no data from randomized controlled clinical trials illustrating the clinical usefulness of pulmonary artery catheters or echocardiographic techniques in hypertensive pregnancy. There are a wealth of data illustrating the haemodynamic profiles of both untreated and treated pre-eclamptic women. Data are also available comparing right heart and left heart filling pressures, demonstrating a relatively poor correlation between the two values. The clinical impact of either measurement is unclear. Data are available illustrating the correlation between echocardiographic techniques and pulmonary artery catheterization.

Brachial plexus involvement as the only expression of hereditary neuropathy with liability to pressure palsies

Hereditary neuropathy with liability to pressure palsies (HNPP) is an autosomal-dominant focal neuropathy characterized by recurrent entrapment neuropathies. Single members of families with HNPP and brachial plexus involvement have been reported previously. We describe a family with three affected members and in which the only symptom of entrapment was recurrent brachial plexopathy. The diagnosis of HNPP in this family was confirmed by both neurophysiological methods and DNA analysis. The distinction between HNPP and hereditary neuralgic amyotrophy is discussed.

Obscurin, a giant sarcomeric Rho guanine nucleotide exchange factor protein involved in sarcomere assembly

Vertebrate-striated muscle is assumed to owe its remarkable order to the molecular ruler functions of the giant modular signaling proteins, titin and nebulin. It was believed that these two proteins represented unique results of protein evolution in vertebrate muscle. In this paper we report the identification of a third giant protein from vertebrate muscle, obscurin, encoded on chromosome 1q42. Obscurin is approximately 800 kD and is expressed specifically in skeletal and cardiac muscle. The complete cDNA sequence of obscurin reveals a modular architecture, consisting of >67 intracellular immunoglobulin (Ig)- or fibronectin-3-like domains with multiple splice variants. A large region of obscurin shows a modular architecture of tandem Ig domains reminiscent of the elastic region of titin. The COOH-terminal region of obscurin interacts via two specific Ig-like domains with the NH(2)-terminal Z-disk region of titin. Both proteins coassemble during myofibrillogenesis. During the progression of myofibrillogenesis, all obscurin epitopes become detectable at the M band. The presence of a calmodulin-binding IQ motif, and a Rho guanine nucleotide exchange factor domain in the COOH-terminal region suggest that obscurin is involved in Ca(2+)/calmodulin, as well as G protein-coupled signal transduction in the sarcomere.

Crystal structure of the alpha-actinin rod reveals an extensive torsional twist

BACKGROUND

Alpha-actinin is a ubiquitously expressed protein found in numerous actin structures. It consists of an N-terminal actin binding domain, a central rod domain, and a C-terminal domain and functions as a homodimer to cross-link actin filaments. The rod domain determines the distance between cross-linked actin filaments and also serves as an interaction site for several cytoskeletal and signaling proteins.

RESULTS

We report here the crystal structure of the alpha-actinin rod. The structure is a twisted antiparallel dimer that contains a conserved acidic surface.

CONCLUSIONS

The novel features revealed by the structure allow prediction of the orientation of parallel and antiparallel cross-linked actin filaments in relation to alpha-actinin. The conserved acidic surface is a possible interaction site for several cytoplasmic tails of transmembrane proteins involved in the recruitment of alpha-actinin to the plasma membrane.

Caesarean section by choice could fulfil the inverse care law

We have assessed knowledge about caesarean sections in a group of North Staffordshire Hospital professionals and patients. Those who were more interested in having a caesarean section without medical indication were the nulliparous health professionals, the majority of whom thought they should be able to choose this option. Paradoxically, this was also the group who were most likely to consider that caesarean section is more expensive and dangerous. The explanation may be that they also felt it to be an easier, less painful and more convenient option.

Effect of meal viscosity and nutrients on satiety, intragastric dilution, and emptying assessed by MRI

The relationship between the intragastric distribution, dilution, and emptying of meals and satiety was studied using noninvasive magnetic resonance imaging techniques in 12 healthy subjects with four polysaccharide test meals of varying viscosity and nutrient content as follows: 1) low-viscosity nonnutrient, 2) low-viscosity nutrient, 3) high-viscosity nonnutrient, and 4) high-viscosity nutrient. Increasing the nutrient content of the high-viscosity meal delayed gastric emptying from 46 +/- 9 to 76 +/- 6 min (P < 0.004), whereas increasing viscosity had a smaller effect. The volume of secretions within the stomach 60 min after ingestion was higher for the high-viscosity nutrient meal (P < 0.04). A simple model to calculate the total volume of secretion added to the test meal is presented. Color-coded dilution map images showed the heterogeneous process of progressive gastric dilution of high-viscosity meals, whereas low-viscosity meals were uniformly diluted. Fullness was found to be linearly related to total gastric volumes for the nutrient meals (R(2) = 0.98) and logarithmically related for the nonnutrient meals (R(2) = 0.96). Fullness was higher for high- compared with low-viscosity meals (P < 0.02), and with the nutrient meals this was associated with greater antral volumes (P < 0.05).