Effect of modern obstetrics on mothers from Third-World countries

Mothers born and raised in third-world countries compared to women born in the United States are on average of shorter size, have less weight, have narrower pelvic dimensions, and give birth to smaller infants without much difficulty. This may be due to a low-protein diet and inadequate prenatal care. Those mothers who were born and raised outside the United States (therefore with narrow pelvic dimensions), but who eat a high-protein diet and receive adequate prenatal care after migrating as adults to the United States, give birth to relatively large infants. This results in a marked cephalopelvic disproportion and severe dystocia, which frequently leads to cesarean birth. It appears that nutritional factors during pregnancy and infancy play a role as important as genetic factors in the etiology of cephalopelvic disproportion.

Genetic and phenotypic analysis of a large (122-member) protein S-deficient kindred provides an explanation for the familial coexistence of type I and type III plasma phenotypes

Protein S deficiency is a known risk factor for thrombosis. The coexistence of phenotypic type I (reduction in total and free antigen) and type III (reduction in free antigen only) protein S deficiencies in 14 of 18 families was recently reported. We investigated the cause of this phenotypic variation in the largest of these families (122 family members, including 44 affected individuals) using both molecular genetic and phenotypic analysis. We have identified a sole causative mutation (Gly295Val) in three family members representative of the variable phenotype. Complete cosegregation of the mutation with reduced free protein S antigen levels was found, regardless of the total antigen level. Analysis of phenotypic data showed high correlations between total protein S antigen and age in both normal and protein S-deficient family members, irrespective of gender. Free protein S antigen levels were not influenced by age, a finding explained by an association between beta-chain containing C4b-binding protein (C4bBP-beta+) antigen levels and age. We propose that the identified Gly295Val mutation causes quantitative, or type I, protein S deficiency, and that as age increases the total protein S antigen level normalizes with respect to the reference plasma pool, giving rise to a type III protein S-deficient phenotype.

Symbol grounding: a bridge from artificial life, to artificial intelligence

This paper develops a bridge from AL issues about the symbol-matter relation to AI issues about symbol-grounding by focusing on the concepts of formality and syntactic interpretability. Using the DNA triplet-amino acid specification relation as a paradigm, it is argued that syntactic properties can be grounded as high-level features of the non-syntactic interactions in a physical dynamical system. This argument provides the basis for a rebuttal of John Searle's recent assertion that syntax is observer-relative (1990, 1992). But the argument as developed also challenges the classic symbol-processing theory of mind against which Searle is arguing, as well as the strong AL thesis that life is realizable in a purely computational medium. Finally, it provides a new line of support for the autonomous systems approach in AL and AI (Varela & Bourgine 1992a, 1992b).

Semiparametric estimation of major gene and family-specific random effects for age of onset

Analysis of familial diseases with variable age of onset is a common problem in human genetics. Most existing methods make some parametric distributional assumption on age of onset, and few methods have been designed with the goal of testing the hypothesis of a Mendelian gene against other hypotheses of familial dependence. We introduce the Cox model with major genetic and random familial effects to model age-of-onset dependence patterns among family members and to incorporate family heterogeneity. This model allows testing for and estimating major gene effects in the presence of residual correlations. Generalized maximum likelihood estimation using a Monte Carlo EM algorithm is used for parameter estimation. The methods are illustrated by a simulated data set and a data set from a case-control family study of breast cancer.

Mutation detection in FGFR2 craniosynostosis syndromes

Five autosomal dominant craniosynostosis syndromes (Apert, Crouzon, Pfeiffer, Jackson-Weiss and Crouzon syndrome with acanthosis nigricans) result from mutations in FGFR genes. Fourteen unrelated patients with FGFR2-related craniosynostosis syndromes were screened for mutations in exons IIIa and IIIc of FGFR2. Eight of the nine mutations found have been reported, but one patient with Pfeiffer syndrome was found to have a novel G-to-C splice site mutation at-1 relative to the start of exon IIIc. Of those mutations previously reported, the mutation C1205G was unusual in that it was found in two related patients, one with clinical features of Pfeiffer syndrome and the other having mild Crouzon syndrome. This degree of phenotypic variability shows that the clinical features associated with a specific mutation do not necessarily breed true.

Involvement of an octamer-like sequence within a crucial region of the androgen-dependent Slp enhancer

Androgen dependence of the mouse sex-limited protein (Slp) gene is conferred by an enhancer encompassing a consensus hormone response element (HRE) and sites for several nonreceptor factors. The footprint IV (FPIV) region of the enhancer plays a key role in hormone- and tissue-specific response, both in vitro and in vivo. We characterized FPIV-binding factors by methylation interference analysis and UV cross-linking of several complexes evident in gel mobility-shift assays. The footprinting analysis revealed that distinct base contacts within the multiple nuclear protein-DNA complexes occurred primarily within a sequence similar to an octamer transcription factor (Oct-1) binding site. With additional data on approximate molecular weights from UV cross-linking, several plausible candidates were tested for their DNA binding and functional activity at FPIV. Oct-like protein binding in gel-shift assays with several cell and tissue extracts was evident using specific competitors and antibodies, but was lower in affinity for FPIV than for an Oct-1 consensus site. Site-directed mutation of the FPIV sequence to a consensus Oct-1 element within the Slp enhancer context increased Oct-1 binding in vitro, but greatly reduced hormonal induction in vivo. This suggested that Oct-1 is not directly involved in response, or alternatively, that Oct-1 bound to the lower-affinity site interacts with neighboring factors significantly differently than Oct-1 bound to a consensus sequence. A sequence overlapping the Oct-like element that was similar to a hepatic nuclear factor-4 (HNF-4) site showed no ability to bind HNF-4 in vitro, nor the related orphan receptor, chicken ovalbumin upstream promoter factor (COUP-TF). Intriguingly, however, expression of COUP-TF in transfection had a dramatic inhibitory effect on response of the androgen-specific enhancer (C' delta9), but did not affect other enhancer configurations that can also be induced by glucocorticoid (C 'delta2). This underscores that, despite extensive sequence identity of C' delta9 and C' delta2, components of the androgen-specific transcription complex differ significantly from that of one that is more generally steroid responsive.

Gene mutations in 21 unrelated cases of phenotypic heterozygous protein C deficiency and thrombosis. Protein C Study Group

Mutations have been identified in the protein C gene in 21 patients with venous thromboembolism and phenotypic heterozygous protein C deficiency. In 20 probands, single mutations were the only abnormalities identified by sequencing all coding regions, intron exon boundaries and the promoter region back to -1540. In one proband 2 mutations were identified and in another family 2 mutations were identified (but not both in the proband). Of the 23 mutations, 18 resulted in predicted amino acid substitutions, 3 were mutations resulting in stop codons, one was a mutation within a consensus splice sequence and another a 9 base pair insertion within exon 5 (this region within exon 5 is proposed as a deletion/insertion hot spot). A novel polymorphism was also, uniquely, identified in the propeptide region of the molecule (Pro-21Pro; CCT to CCC) in a kindred from Hong Kong. Cosegregation of the protein C gene mutation with protein C deficiency could be determined in 13 families. In a further family, phenotypic protein C deficiency and the genetic mutation cosegregated in only 4/5 members. The first thrombotic incident occurred in the probands between the ages of 11 and 59 years and 12 individuals suffered recurrent thrombosis. Thrombosis occurred in at least one other family member in 9/21 families, but in 2 of these it was inconsistently associated with protein C deficiency. An independent genetic risk factor, factor V Arg506Gln (FV Leiden) was identified in 2 probands (and 3 family members) and in 4 protein C deficient members of a third family but not in the proband. The results suggest that in the majority of probands with thrombosis and phenotypic protein C deficiency, a single protein C gene mutation is associated with thrombosis. However, it is also possible that additional unknown genetic risk factors contribute to the thrombotic risk. An added, acquired, risk factor leads to thrombosis at an early age (< 25 years).

Positron emission tomography in the detection and management of metastatic melanoma

Initial reports suggest that positron emission tomography with [18F]fluorodeoxyglucose (FDG-PET) may offer greater diagnostic accuracy and versatility than conventional radiology in staging patients with metastatic melanoma. We reviewed the first 100 melanoma patients to have PET imaging at our institution. PET findings were correlated with all other available results, including plain X-ray, computed tomography (CT), magnetic resonance (MR) imaging, bone scintigraphy, clinical findings and histopathology. A total of 415 metastatic lesions were evaluated, 388 (93%) of which were detected by PET. In 20 patients, PET detected 24 metastases up to 6 months earlier than conventional imaging or physical examination. Selection of surgical or medical management was specifically influenced by PET findings in 22 patients, and PET was used to clarify another 12 cases where CT was inconclusive. In nine patients undergoing chemotherapy, PET was used to assess response to treatment. We conclude that FDG-PET can accurately detect metastatic melanoma with a single non-invasive scan, and can demonstrate some metastases months before conventional imaging techniques. PET can improve the selection of patients for surgery, has potential for monitoring response to treatment and may prove a cost-effective means of staging melanoma patients.

Contextual dependence of steroid receptor function on an androgen-responsive enhancer

The enhancer of the mouse sex-limited protein (Slp) gene includes a consensus hormone response element (HRE) that interacts with several auxiliary elements for steroid induction. The 160-bp fragment. C' delta 2, confers response to androgen or glucocorticoid in transfection, while a 120-bp subfragment, C' delta 9, is activated only by androgen in some cells. Site-directed mutants were tested to identify elements affecting differential response of androgen or glucocorticoid receptors (AR, GR). While most mutations of C' delta 2 affected induction by either steroid similarly, disruptions of the consensus HRE or an octamer-like sequence were more severe for GR than AR activity. An HRE half-site was critical to androgen-specific induction of C' delta 9 but had little impact in the nonspecific C' delta 2 context. In DNase I footprinting, full-length AR and GR bound similarly to the consensus HRE but dissimilarly to nonconsensus sites. Intriguingly, NF-kappa B bound the region of C' delta 2 absent from C' delta 9. Expression of I kappa B decreased response of C' delta 2, but not C' delta 9, confirming a permissive role of NF-kappa B in steroid activation. In this case, different factors may associate with receptors in the presence of NF-kappa B than those that confer androgen specificity in NF-kappa B's absence, suggesting that exclusion of some factors from a specific transcription complex is as crucial as inclusion of others. This dissection of C' delta 2 and C' delta 9 in vitro reveals subtle distinctions in AR and GR interactions that may underlie specific hormonal response in vivo.

Evaluation of the effectiveness of guidelines, audit and feedback: improving the use of intravenous thrombolysis in patients with suspected acute myocardial infarction

OBJECTIVE

To determine the effectiveness of medical audit as a means of improving the use of intravenous thrombolytics in patients with suspected acute myocardial infarction.

DESIGN

Time-series analyses of observations in four study hospitals conducting repeated audits and feedback compared to a control hospital.

SETTING

Five district general hospitals in North West Thames Region between April 1991 and July 1992.

SUBJECTS

2593 patients admitted as emergencies with a suspected acute myocardial infarction.

MAIN OUTCOME MEASURES

Proportion of eligible cases receiving intravenous thrombolytic therapy observed in each audit and proportion of patients in whom this therapy was used appropriately.

RESULTS

In the baseline audits, the proportions of eligible cases receiving thrombolytic therapy in the four study hospitals were 94%, 60%, 58% and 57%, and 53% in the control hospital. After three further audits in each study hospital over the subsequent year, the observed proportions had changed to 88% (to 6%), 92% (+32%), 95% (+37%), and 7796 (+20%). Meanwhile the proportion in the control hospital rose to 68% (+15%). The trend over time was significant in the second and third hospitals but not in the other two study hospitals or the control hospital. Reclassification of those cases in which the reliability of the diagnosis was poor altered the extent but not the direction of observed trends. Generally, the appropriateness of use of thrombolytic therapy increased with increasing treatment rates. There was a suggestion, however, that continued auditing in the presence of high treatment rates may have led to a reduction in appropriateness.

CONCLUSIONS

medical audit can be an effective means of improving the use of intravenous thrombolytics. It is possible that over auditing may result in greater inappropriate use.

Fracture-Dislocations You Can't Afford to Miss

Occult dislocations can accompany extremity fractures and may lead to serious complications if undetected and untreated. Physicians, therefore, need to watch for uncommon trauma like distal radius fractures with radioulnar joint disruption (Galeazzi fractures), proximal ulna fractures with radial head dislocation (Monteggia fractures), and midfoot dislocations with or without fracture (Lisfranc injuries). Injury recognition involves comparing important historical features like a fall onto an outstretched hand, physical exam findings such as the nature of the pain, and sometimes-subtle radiographic clues. Treatment is usually surgical.

Evidence for the late origin of introns in chloroplast genes from an evolutionary analysis of the genus Euglena

The origin of present day introns is a subject of spirited debate. Any intron evolution theory must account for not only nuclear spliceosomal introns but also their antecedents. The evolution of group II introns is fundamental to this debate, since group II introns are the proposed progenitors of nuclear spliceosomal introns and are found in ancient genes from modern organisms. We have studied the evolution of chloroplast introns and twintrons (introns within introns) in the genus Euglena. Our hypothesis is that Euglena chloroplast introns arose late in the evolution of this lineage and that twintrons were formed by the insertion of one or more introns into existing introns. In the present study we find that 22 out of 26 introns surveyed in six different photosynthesis-related genes from the plastid DNA of Euglena gracilis are not present in one or more basally branching Euglena spp. These results are supportive of a late origin for Euglena chloroplast group II introns. The psbT gene in Euglena viridis, a basally branching Euglena species, contains a single intron in the identical position to a psbT twintron from E.gracilis, a derived species. The E.viridis intron, when compared with 99 other Euglena group II introns, is most similar to the external intron of the E.gracilis psbT twintron. Based on these data, the addition of introns to the ancestral psbT intron in the common ancester of E.viridis and E.gracilis gave rise to the psbT twintron in E.gracilis.

Health promotion and African-Americans: from personal empowerment to community action

PURPOSE

Self-help among African-Americans is that tradition of individual and group efforts aimed toward racial progress and defending against a hostile society. The purpose of this paper is to encourage African-Americans, regardless of income, to take personal responsibility for their health. This review discusses each side of the individual versus societal responsibility issue and provides a rationale for integrating these two perspectives. It argues that the tradition of community-based self-help among African-Americans is a mechanism for personal empowerment that can lead to collective action; it therefore has important implications for the improvement of African-American health.

SEARCH METHODS

The search made use of a computer-based inquiry with self-help, community health empowerment, and African-American or blacks used as descriptors. We also used a computerized search by the last names of key authors writing in the area of minority health. The review was limited to references between 1964 and 1994. The review also relied on our own professional libraries. Finally, 15 knowledgeable individuals employed at universities around the country were queried about their work, focusing on this subject. They were asked about their perceptions of the issues pertinent to the role of personal and societal responsibility in modifying health behaviors of African-Americans. SUMMARY OF IMPORTANT POINTS: Effective health behavior change strategies with black populations will require an integration of personal responsibility and advocacy for social systems change. The formation of effective self-help community-based coalition partnerships is viable strategy for forging systemic changes to address the health disparity problem.

MAJOR CONCLUSIONS

The discussion concludes that blacks should hold themselves more personally responsible for solving their own problems while rejecting debilitating forms of extreme self-blame. Affiliation with self-help organizations and community coalitions for health empowerment is offered as a strategy for community infrastructure development with potential for improving quality of life.

RAS and FMS mutations following cytotoxic therapy for childhood acute lymphoblastic leukaemia

Patients who have received cytotoxic therapy for primary neoplastic disease are at an increased risk of developing secondary (therapy-related) acute myeloid leukaemia (AML) or myelodysplasia (MDS). RAS and FMS mutations have been observed in patients with AML and MDS. It has been suggested that the mutational status within these genes may be predictive of early secondary leukaemic disease. In this study we have screened 50 haematologically normal patients in complete remission from childhood acute lymphoblastic leukaemia (ALL) for activating point mutations in the RAS and FMS proto-oncogenes. Such patients may be considered at risk of therapy-related disease. Codons 12, 13 and 61 were screened in RAS and codon 969 in FMS using the polymerase chain reaction (PCR) followed by oligonucleotide hybridization (ONH). Three of the 50 patients (6%) were found to harbour N12 RAS mutations. One of these three patients (2%) had both a N12 RAS and FMS 969 mutation. Upon sequencing the RAS mutations, substitutions of serine, cysteine and aspartic acid for glycine were identified. The FMS 969 mutation was also confirmed, by sequencing, as a histidine substitution. RAS mutations were not detected in presentation samples indicating that these lesions have been somatically acquired presumably subsequent to cytotoxic therapy for the primary disease. Continued follow-up of these patients may indicate a role for these mutations in the development of secondary malignancies.

Generation and molecular cytogenetic characterization of a radiation-reduction hybrid panel for human chromosome 6

A neoR marked chromosome-6 containing hybrid (D113JA) was used to generate a panel of 15 radiation-reduced hybrid cell lines. The panel was constructed by irradiating microcells isolated from D113JA at 800 or 8000 rads, providing different levels of chromosome 6 retention. These hybrids have been systematically analyzed using interspersed repetitive elements, previously assigned markers for chromosome 6, and fluorescent in situ hybridization (FISH). As expected, G418 selection has favored the retention of fragments near the insertion site of the neoR gene (6q16). The panel as constituted provides an important resource for regional assignment of molecular markers, especially to regions on 6q.

An algorithm for Monte Carlo estimation of genotype probabilities on complex pedigrees

Exact probability and likelihood computation on complex pedigrees is often infeasible, since exact methods are too computationally intensive even with today's computing technology. A statistical tool, Markov chain Monte Carlo (MCMC), is increasingly being explored as a technique for estimating probabilities of genotypic configurations on pedigrees conditional on phenotypic data. However, this conditional probability distribution on a complex pedigree is, in general, multimodal, and multimodality is one of the major difficulties in MCMC exploration of a probability surface. In this paper, a new member of the MCMC Metropolis-Hastings class of algorithms is proposed; the heated-Metropolis algorithm. The algorithm achieves passage through low probability states to other local modes of the probability distribution, and so provides much improved estimates of probabilities of interest. The example considered is the estimation of the probabilities of carrier genotype for the founders of a complex pedigree in which a very rare lethal recessive trait is segregating.

Pharmacokinetic properties of methadone hydrochloride after single intramuscular administration in adult dairy goats

Pharmacokinetic parameters of methadone were studied in adult dairy goats. Five goats were each given methadone hydrochloride as a single 0.2 mg/kg of body weight dosage by intramuscular (IM) administration. Plasma methadone concentrations were determined for 96 h after dosing. Plasma methadone concentrations after IM administration were best described by an open one-compartment model. Overall elimination half-life (t1/2) was 1.38 h. Peak plasma concentrations were reached 0.25 h after dosing, and the actual plasma concentration averaged 37.8 ng/ml (SD = 12.76) at that time. The data obtained from this study suggest that plasma concentrations, similar to those that are analgesic in humans, can be achieved after IM administration of methadone at a dose rate of 0.2 mg/kg of body weight. In addition, these plasma concentrations can be maintained for up to 3 h after a single injection and, therefore, may provide satisfactory analgesia for such period.

Symptoms and health status before and six weeks after open cholecystectomy: a European cohort study.ECHSS Group. European Collaborative Health Services Study Group

The impact of open cholecystectomy on patients' symptoms and health status and their level of satisfaction has been examined to provide a basis for comparison with newer rival treatments. A prospective cohort study using patient and surgeon completed questionnaires before and six weeks after surgery was carried out in 14 general hospitals in eight European countries. Five hundred and eighty three patients were recruited consecutively in 1990 to 1991. Information on their symptoms, general health status, activities of daily living, and satisfaction with their care were collected. After surgery 42.8% of patients reported that they were free of symptoms. Symptoms varied in their responsiveness to surgery--six weeks after surgery 89% of those who had complained of vomiting had improved, 81% of nausea, 69% of loss of appetite, 65% of abdominal pain, and 51% of flatulence. In contrast 28.1% of patients still suffered from flatulence and 23.5% continued to complain of abdominal pain. Most patients' (62.7%) general health improved, 28% were unchanged, and 9.3% were worse. After surgery most patients reported no restrictions in their normal social activities (75-90% depending on the activity) and most (89.5%) felt the results of their operation had been as expected or better than expected. Most patients undergoing open cholecystectomy reported an improvement in their symptoms, health status, and social functioning. This was reflected in their high level of satisfaction. Some patients, however, gained no benefit and a small proportion were worse than before surgery.

Mammalian cell gene mutation assays working group report

As part of the International Workshop on Standardization of Genotoxicity Test Procedures, in Melbourne, 27-28 February 1993, various international guidelines were examined with respect to protocol issues in the area of mammalian cell gene mutation assays. The working group on mammalian cell gene mutation assays discussed a wide range of protocol issues related to study design; in most cases the recommendations are reasonably consistent with existing guidelines. Agreement was reached on several issues as follows. The upper limit of concentration for testing non-toxic substances should be 10 mM or 5 mg/ml, whichever is lower. For testing toxic substances the criteria of an acceptable upper limit of concentration should yield 10-20% survival. Any of several established mammalian cell mutation assays (L5178Y TK+/-, CHO/HPRT, AS52/XPRT, V79/HPRT) can be used to evaluate mutagenesis in mammalian cells; the ouabain (Na/K-ATPase) system is not an acceptable mutation assay for routine evaluation of mutagenesis in mammalian cells. Ability to recover small colonies must be convincingly demonstrated when using the L5178Y TK+/- mouse lymphoma assay. In the mouse lymphoma assay (L5178Y TK+/-), colonies in positive controls and at least two (if available) representative positive doses of the test compound should be sized if a positive response is seen; in the event of a negative response due to the test compound, colony sizing of the positive control is necessary to validate the conduct of the assay. Testing both in the presence and absence of S9 metabolic activation is necessary. It was not possible to come to a firm conclusion about the length of treatment. There was a general agreement that extended treatment times (> 2 cell cycles) often bear more disadvantages than advantages and should only be used with adequate justification. It is not necessary to repeat clear positive or clear negative tests when the assay has been adequately performed; this recommendation differs significantly from the UK guidelines. If treatment groups are not replicated, the numbers of doses tested should be increased; this recommendation differs significantly from the UK guidelines. Each laboratory should establish a historical database for the performance of a given assay in that laboratory.

Finding noncommunicating sets for Markov chain Monte Carlo estimations on pedigrees

Markov chain Monte Carlo (MCMC) has recently gained use as a method of estimating required probability and likelihood functions in pedigree analysis, when exact computation is impractical. However, when a multiallelic locus is involved, irreducibility of the constructed Markov chain, an essential requirement of the MCMC method, may fail. Solutions proposed by several researchers, which do not identify all the noncommunicating sets of genotypic configurations, are inefficient with highly polymorphic loci. This is a particularly serious problem in linkage analysis, because highly polymorphic markers are much more informative and thus are preferred. In the present paper, we describe an algorithm that finds all the noncommunicating classes of genotypic configurations on any pedigree. This leads to a more efficient method of defining an irreducible Markov chain. Examples, including a pedigree from a genetic study of familial Alzheimer disease, are used to illustrate how the algorithm works and how penetrances are modified for specific individuals to ensure irreducibility.

A clinical follow-up of British patients with FG syndrome

The FG syndrome is an X-linked recessive mental retardation syndrome. Ten patients are reviewed with special emphasis on the natural history of the intellectual development, constipation, and the prognosis for growth and behaviour. Six out of 10 patients are still macrocephalic, and there is no evidence for a specific growth pattern with respect to height. The degree of mental retardation is is usually severe. The behaviour is characteristically friendly, sociable and over-talkative, with periodic aggression. Six patients have seizures. A characteristic progression seems to occur from congenital hypotonia with joint hyperlaxity at birth, to joint contractures with apparent spasticity and unsteady gait later in life. The constipation was a temporary problem in five cases. The cowlick and the fetal pads persist and are important, but not specific, for the diagnosis.

Laminin adhesion-selected primary human colon-cancer cells are more tumorigenic than the parenteral and nonadherent cells

Laminin has been shown to promote the malignant phenotype and the level of the 32/67 Kd laminin receptor has been found to correlate with Dukes' staging of colon cancer. A biopsy of a Dukes' stage B2 human colon carcinoma formed a tumor in a nude mouse after coinjection with Matrigel. The parental tumor and the murine tumor appeared identical at the histological level. A cell line LCC-C1 was established from the murine tumor. The cell line appeared moderately differentiated although it did not produce mucin in vitro; however, the xenograft in vivo did produce low levels of mucin. Laminin adherent and non-adherent cell lines were selected. The parental and the laminin-selected cell subclones adhered equally well to plastic and to fibronectin and showed similar growth rates on plastic. When injected subcutaneously into nude mice, the laminin-adherent cells formed relatively undifferentiated tumors that were twice as large as the parental cell tumors whereas the laminin non adherent cells formed very small, but highly differentiated tumors. These data demonstrate that subpopulations of tumor cells which differ in their tumorigenic properties can be selected based on their adhesion to laminin and thus provide models for studying the mechanisms of tumor growth.

Preliminary findings of high-dose thiamine in dementia of Alzheimer's type

Thiamine is important not only in the metabolism of acetylcholine but also in its release from the presynaptic neuron. Pathologic, clinical, and biochemical data suggest that thiamine deficiency is detrimental to the cholinergic system and that thiamine-dependent enzymes may be altered in Alzheimer's disease. Two previous studies reported contradictory results in patients with dementia of Alzheimer's type treated with 3 g/day of thiamine. In the present study, we examined the effects of 3 to 8 g/day thiamine administered orally. Our results suggest that thiamine at these pharmacologic dosages may have a mild beneficial effect in dementia of Alzheimer's type. The mechanism of the observed effect is unknown, but the findings warrant further investigation, not only for their therapeutic implications but for their possible etiologic clues. In addition, the results suggest long-term carry-over effects that should be considered in the design of future studies.

Personal services

Dutch experience seems to show that a liberal societal attitude to sex and sexuality encourages young people to be more confident in asking for the contraceptive services they need, writes Elinor Thompson.

Obstacles to medical audit: British doctors speak

Currently, British doctors are being encouraged by government, managers and their professional associations to undertake medical audit. How easy a task will it be to introduce audit? In an attempt to find out, doctors working in general, geriatric and accident and emergency medicine in four district general hospitals were interviewed. Twenty-eight consultants and 34 junior doctors participated. Generally speaking, doctors accepted the need for audit. In this paper we have focussed deliberately on their worries, since it is these which are of most importance in developing better methods of implementation. The 19 obstacles to audit that respondents identified can be grouped into four categories: perceptions of the need for and the role of audit; practical considerations; the effects of audit; and anxieties about the use of audit. In general, criticisms were levelled at the way audit was being implemented rather than at the principles of the approach. While some obstacles could be overcome by simple, practical measures, others will require a change in doctors' knowledge, beliefs and attitudes. The difficulty of achieving such changes should not be underestimated.

Efficacy and toxicity of multiagent chemotherapy and low-dose involved-field radiotherapy in children and adolescents with Hodgkin's disease

PURPOSE

Between May 1980 and September 1990, 85 patients with Hodgkin's disease were treated with a regimen designed to increase cure rates while reducing late toxicity.

PATIENTS AND METHODS

Therapy consisted of five cycles of cyclophosphamide, Oncovin (vincristine; Eli Lilly and Co, Indianapolis, IN), and procarbazine (COP), alternated with four cycles of doxorubicin, bleomycin, vinblastine, and dacarbazine (ABVD) and low-dose (20 Gy) regional radiotherapy. Vincristine and cyclophosphamide were administered as tolerated during irradiation and during the 2- to 4-week rest period between radiation volumes. The need for staging laparotomy was defined by clinical presentation.

RESULTS

The median age at diagnosis was 14 years (range, 4 to 20), and 56% of patients were male. The majority (67%) had stage III or IV disease and 68% (19 of 28) of stage II patients had bulky mediastinal disease. Nodular sclerosing histology predominated (67%). Ninety-three percent of patients were alive without disease with a median follow-up of 4.1 years. Abnormalities were detected on chest roentgenograms and/or pulmonary function tests in 58% and 25% of clinically asymptomatic patients who were tested at least 1 year after completion of therapy. The only symptomatic patient had pulmonary fibrosis after treatment with bleomycin (20 U/m2) and mantle (20 Gy)/lung (13 Gy) irradiation, and developed multiple spontaneous pneumothoraces that required cortical stripping. One patient had congestive heart failure 19 months post-treatment, and two had abnormalities on echocardiograms. Thyroid abnormalities occurred in 21 (27%) patients who were assessable for late toxicity. The majority of female patients have had regular menstrual cycles. Six developed ovarian failure, and 10 have had a total of 17 pregnancies. Other than one documented case of oligospermia, information was not available on male fertility.

CONCLUSION

The results demonstrate excellent disease control for the COP/ABVD regimen, with acceptable toxicity.

The significance of serum oligoclonal bands in neurological diseases

The presence of oligoclonal bands (OCBs) of immunoglobulin G (IgG) in CSF provides evidence for the occurrence of a humoral immune response, but it is not always appreciated that the oligoclonal IgG may have originated in the serum. To determine the diagnostic significance of serum OCBs 146 patients with serum OCBs were identified among 1874 patients with suspected neurological disorders (7.6%). Clear diagnoses had been made in 112 of these patients: in 56 identical CSF and serum bands were present, revealing a systemic immune response, while in 46 additional unique CSF bands indicated that intrathecal IgG synthesis was also occurring. In the first group neoplasia and peripheral neuropathies accounted for over 50% of the diagnoses, infections and systemic inflammatory disorders for 32%, and multiple sclerosis was diagnosed in only one case. These figures contrast considerably with those reported for patients with CSF OCBs alone. Diagnoses in the second group of patients, with unique CSF OCBs in addition to serum OCBs, resembled those among patients with CSF OCBs alone. Examining CSF and serum in parallel for OCBs of IgG provides more diagnostic information than examining CSF alone, and the latter is potentially misleading.

Achieving irreducibility of the Markov chain Monte Carlo method applied to pedigree data

Markov chain Monte Carlo (MCMC) methods have been explored by various researchers as an alternative to exact probability computation in statistical genetics. The objective is to simulate a Markov chain with the desired equilibrium distribution. If the transition kernel is aperiodic and irreducible, then convergence to the equilibrium distribution is guaranteed; realizations of the Markov chain can thus be used to estimate desired probabilities. Aperiodicity is easily satisfied, but, although it has been shown that irreducibility is satisfied for a diallelic locus, reducibility is a potential problem for a multiallelic locus. This is a particularly serious problem in linkage analysis, because multiallelic markers are much more informative than diallelic markers and thus highly preferred. In this paper, the authors propose a new algorithm to achieve irreducibility of the Markov chain of interest by introducing an irreducible auxiliary chain. The irreducibility of the auxiliary chain is obtained by assigning positive probabilities to a small subset of the genotypic configurations inconsistent with the data, to bridge the gap between the irreducible sets.

Pleiotropic effects of antithrombin strand 1C substitution mutations

Six different substitution mutations were identified in four different amino acid residues of antithrombin strand 1C and the polypeptide leading into strand 4B (F402S, F402C, F402L, A404T, N405K, and P407T), and are responsible for functional antithrombin deficiency in seven independently ascertained kindreds (Rosny, Torino, Maisons-Laffitte, Paris 3, La Rochelle, Budapest 5, and Oslo) affected by venous thromboembolic disease. In all seven families, variant antithrombins with heparin-binding abnormalities were detected by crossed immunoelectrophoresis, and in six of the kindreds there was a reduced antigen concentration of plasma antithrombin. Two of the variant antithrombins, Rosny and Torino, were purified by heparin-Sepharose and immunoaffinity chromatography, and shown to have greatly reduced heparin cofactor and progressive inhibitor activities in vitro. The defective interactions of these mutants with thrombin may result from proximity of s1C to the reactive site, while reduced circulating levels may be related to s1C proximity to highly conserved internal beta strands, which contain elements proposed to influence serpin turnover and intracellular degradation. In contrast, s1C is spatially distant to the positively charged surface which forms the heparin binding site of antithrombin; altered heparin binding properties of s1C variants may therefore reflect conformational linkage between the reactive site and heparin binding regions of the molecule. This work demonstrates that point mutations in and immediately adjacent to strand 1C have multiple, or pleiotropic, effects on this serpin, leading ultimately to failure of its regulatory function.

Seroprevalence of human immunodeficiency virus among adolescent attendees of Mississippi sexually transmitted disease clinics: a rural epidemic

Human immunodeficiency virus (HIV) infection among adolescents is causing increasing concern, and teenagers attending sexually transmitted disease (STD) clinics run a high risk of contracting it. To determine the status of HIV infection in a Mississippi adolescent population, we evaluated seroprevalence rates for adolescents attending Mississippi State Department of Health STD clinics from 1988 to 1990. During this 2-year period, 9855 adolescents (aged 13 to 20 years) attended STD clinics, and HIV antibody was confirmed in 39 (seroprevalence rate 4.0/1000; 95% confidence interval [CI] 2.7 to 5.2). Seropositive rates were almost equal for male and female subjects (4.1/1000 and 3.8/1000, respectively), suggesting predominantly heterosexual transmission. Rates among blacks were 3.5 times higher than among whites. Adolescents with HIV infection were identified throughout the state, irrespective of urban centers. Rates among the smallest counties (ie, population less than 25,000) were not significantly different from those of the largest counties (ie, population greater than 100,000). Mississippi's rank in the top 10 states for other STDs and the state's high teenage pregnancy rate make it an epicenter of the HIV epidemic among adolescents.

Ewing's sarcoma: local tumor control and patterns of failure following limited-volume radiation therapy

Sixty children with localized osseous Ewing's sarcoma were treated between 1978 and 1988 with induction chemotherapy (cyclophosphamide, adriamycin), irradiation and/or surgery, and 10 months of maintenance chemotherapy (cyclophosphamide, adriamycin, dactinomycin, vincristine). Following induction chemotherapy, 43 patients received primary radiation therapy to limited radiation volumes defined by post-chemotherapy residual soft tissue tumor extension and initial osseous tumor extent. Irradiation was defined as low dose at 30-36 Gy (median 35 Gy) for 31 cases with objective response to induction chemotherapy and high dose at 50-60 Gy (median 50.4 Gy) for 12 patients with poor response to induction chemotherapy or with tumors greater than or equal to 8 cm. Overall event-free survival at 5 years is 59% and local tumor control is 68%. Initial failures have been local (12), simultaneous local and distant failures (7), and distant (6). In the surgical resection group, 14 patients had complete resection without radiation therapy, and 3 patients had microscopic residual plus 35-41 Gy; 100% local control has been maintained. In 43 patients with primary radiation therapy group, local tumor control is 58% (p = .004). Despite limited radiation volume, 18/19 local failures occurred centrally within the bone, well within the radiation volume. Imaging response to induction chemotherapy predicted local tumor control in the radiation therapy group: 62% with complete response/partial response versus 17% with no response/progressive disease (p less than 0.01). Local tumor control related strongly to primary tumor size in the radiation therapy group; among 31 cases receiving 35 Gy, local tumor control is 90% for lesions less than 8 cm versus 52% for tumors greater than or equal to 8 cm (p = .054). The central pattern of local failure in this experience suggests the effectiveness of limited radiation volume. The overall local tumor control rate following the tested dose level of 35 Gy appears to be inadequate, although results in selected cases with tumors less than 8 cm in greatest tumor dimension indicate potential efficacy in a yet limited experience.