Treatment of diencephalic syndrome with chemotherapy: growth, tumor response, and long term control

BACKGROUND

The diencephalic syndrome (DS), which is manifested by progressive emaciation and failure to thrive in an apparently alert, cheerful infant, usually is due to a low grade hypothalamic glioma. Treatment with aggressive surgery and/or radiotherapy is variably successful in controlling disease and may result in severe neurologic sequelae. Chemotherapy recently has been shown to be effective in patients with low grade gliomas of childhood, but it is used infrequently in those with DS.

METHODS

The authors evaluated the efficacy of a regimen of carboplatin and vincristine on improving weight, causing tumor shrinkage, and delaying the need for alternative therapies in seven children (ages 9-20 months; median age, 11 months) with DS. Five patients weighed less than the 5th percentile for their age at the start of the study, one weighed within the 10th percentile, and one weighed within the 25th percentile.

RESULTS

At follow-up (range, 6-54 months; median, 28 months), the patients' weights had increased by 66-95% (median, 80%). On magnetic resonance imaging, four patients had a >50% reduction in tumor mass, one had a 25-50% reduction, and two had stable disease. In those patients with radiographic response to treatment, weight gain was accomplished with oral feedings in four of five patients, whereas those with stable disease required nasogastric, nasojejunal, or gastrostomy tube supplementation to maintain weight. Disease progression occurred at a median of 24 months after initiation of chemotherapy, and two patients remained free of progressive disease at last follow-up. Five patients were alive a median of 59 months from diagnosis. The need for radiation or other therapies was delayed in six of seven children. Therapy was tolerated without significant toxicities.

CONCLUSION

The authors conclude that treatment of DS with a carboplatin and vincristine regimen results in demonstrable weight gain, may result in tumor shrinkage, and in some cases, significantly delays the need for alternative therapies.

Volunteers as members of the home healthcare and hospice teams

A volunteer program has multiple advantages to the patients, their families, their nurses, the hospice, and the volunteers themselves (Harris, 1990). Home care volunteerism make good sense. If properly administered, it is cost-efficient and delivers a quality of care that can be acquired in no other way (Sodano, 1997;764). Given the many changes that continue to take place in home healthcare and hospice regulations and financing, volunteers are a vital component of both programs so that patients and families continue to receive high-quality care. Volunteers are important members of the home healthcare and hospice teams.

Immunohistochemical localization of the neural cannabinoid receptor in rat brain

The cannabinoid receptor family consists of two inhibitory G-protein-coupled receptors, CB1 and CB2. CB1 is distributed primarily in neural tissue, whereas CB2 is distributed predominantly in immune cells. The distribution of cannabinoid receptors in neural tissue has been demonstrated by using ligand binding autoradiography with CP55,940, a high-affinity cannabinoid receptor ligand, and in situ hybridization. However, the localization of CB1 within individual cells in the brain remains to be defined. In the present study, domain-specific polyclonal antibody to amino acids 83-98 of CB1 was used to define the expression of the neural cannabinoid receptor at the histochemical level. The use of CB1-specific antiserum is advantageous in view of recent reports that CB2 also is expressed in the brain and binds CP55,940. Thus, utilization of anti-CB1 antiserum would allow for the specific detection of CB1 protein expression. The regional staining pattern for CB1 in rat brain was consistent with that reported for CB1 using ligand binding autoradiography and in situ hybridization. Intense immunoreactivity was present in the hippocampal formation, the basal ganglia, and the molecular layer of the cerebellum. Moderate immunohistochemical staining was observed in the olfactory bulb, piriform cortex, cerebral cortex, and the granular layer of the cerebellum. In addition, immunoreactive staining was concentrated on afferent projections and dendritic processes of neuronal cells and was present within cell bodies and on cell surfaces. These data indicate that the anti-CB1 antibody is a sensitive probe for the unequivocal histological discrimination of CB1 protein expression.

Expression of neurogenic basic helix-loop-helix genes in primitive neuroectodermal tumors

The basic helix-loop-helix (bHLH) class of transcription factors plays a pivotal role in tissue-specific determination and differentiation. Moreover, dysregulated expression or loss of function of these factors contributes to leukemogenesis and solid tumor development. Neurogenesis is regulated by genes of the NEUROD/atonal and ACHAETE SCUTE families. We analyzed expression of human NEUROD1, NEUROD2, NEUROD3, and ACHAETE SCUTE 1 (HASH1) in cerebellar and cerebral primitive neuroectodermal tumors (PNETs), gliomas, and cell lines derived from a variety of neuroectodermal tumors by Northern analysis and in situ hybridization. NEUROD1 was expressed in each of the 12 medulloblastoma specimens, whereas NEUROD2 and NEUROD3/neurogenin were expressed in partly overlapping subsets of medulloblastomas. All of the tumors that presented with distant metastases expressed NEUROD3. The only other NEUROD3-positive tumor progressed early in treatment. Human ACHAETE SCUTE homologue (HASH1) was not expressed in medulloblastomas (infratentorial PNETs) but was expressed in three of five supratentorial PNETs. Neuroectodermal tumor cell lines derived from other sites (e.g., neuroblastoma and retinoblastoma) expressed NeuroD and ACHAETE SCUTE family members. No NEUROD message was detected in glial tumors or cell lines. Neurogenic bHLH transcription factor expression patterns suggest that specific family members may contribute to or reflect biological differences that arise during malignant transformation.

Likelihood-based models for genetic linkage analysis using affected sib pairs

Risch [Am J Hum Genet 1990; 46:229-253] recently developed a likelihood method for testing genetic linkage using affected sib pairs. This paper proposes a reparameterization of the Risch likelihood in terms of genetic variance components divided by the affected-sib-pair ascertainment probability. The new parameters allow for ease of interpretation, particularly for multilocus models. A single-degree-of-freedom test of the total disease genetic effect at a marker locus can be constructed that has power comparable to the likelihood ratio 'triangle' test. Extension of the models to other types of relative pairs is also discussed. The models may be used in genome scanning and in studying single or multilocus models of inheritance.

An autosomal screen for genes that predispose to celiac disease in the western counties of Ireland

Celiac disease is a strongly heritable gastrointestinal illness that is an especially important model of the genetically complex multifactorial immune mediated diseases. The HLA component of celiac disease (a specific HLA-DQ heterodimer)is largely established and is relatively uncomplicated, and the environmental component (gluten and related grain storage proteins in the diet) is remarkably well understood. Previous family studies of celiac disease suggested that there is at least one important non-HLA locus. This locus may be a stronger genetic factor than HLA, and it apparently has a recessive mode of inheritance. We used a three step genome screening protocol to identify loci that contribute to celiac disease in the western counties of ireland, a region with the highest prevalence of celiac disease in the world. The most significant of several possible non-HLA loci that we found was on chromosome 6p about 30 cM telomeric from HLA. It has a multipoint maximum lod score of 4.66 (compared with 4.44 for HLA-DQ) and appears to have a recessive mode of inheritance. Our study localizes and provides strong evidence for linkage of at least one non-HLA locus to celiac disease and may serve as a prototype for an efficient approach to screening the human genome for loci that contribute to complex diseases.

Energy transfer from carotenoid and FMO-protein in subcellular preparations from green sulfur bacteria. Spectroscopic characterization of an FMO-reaction center core complex at low temperature

The Fenna-Matthews-Olson (FMO)-protein and the FMO-reaction center (RC) core complex from the green sulfur bacterium Chlorobium tepidum were examined at 6 K by absorption and fluorescence spectroscopy. The absorption spectrum of the RC core complex was obtained by a subtraction method and found to have fiye peaks in the QY region, at 797, 808, 818, 834 and 837 nm. The efficiency of energy transfer from carotenoid to bacteriochlorophyll a in the RC core complex was 23% at 6 K, and from the FMO-protein to the core it was 35%. Energy transfer from the FMO-protein to the core complex was also measured in isolated membranes of Prosthecochloris aestuarii from the action spectra of charge separation. Again, a low efficiency of energy transfer was obtained, both at 6 K and at room temperature.

Testing for homogeneity of Hardy-Weinberg disequilibrium using data sampled from several populations

Olson (1993, Annals of Human Genetics 57, 291-295) proposed a large-sample test of Hardy-Weinberg equilibrium when genotype data are sampled from several populations with different allele frequencies. The test assumes that a ratio measure of disequilibrium is constant across the populations. In this paper, we consider the problem of testing the assumption of homogeneity of that ratio and propose both a large-sample test and an exact test. The large-sample test is appropriate if sample sizes in all strata are sufficiently large, but is strongly anticonservative if some strata are small. In the latter case, the exact test is preferred and we approximate the P-value of this test using a Markov chain Monte Carlo approach.

Mapping of a susceptibility locus for Crohn's disease on chromosome 16

Crohn's disease (CD) and ulcerative colitis are the major forms of chronic inflammatory bowel diseases in the western world, and occur in young adults with an estimated prevalence of more than one per thousand inhabitants. The causes of inflammatory bowel diseases remain unknown, but genetic epidemiology studies suggest that inherited factors may contribute in part to variation in individual susceptibility to Crohn's disease. A genome-wide search performed on two consecutive and independent panels of families with multiple affected members, using a non-parametric two-point sibling-pair linkage method, identified a putative CD-susceptibility locus on chromosome 16 (P less than 0.01 for each panel). The localization was centered around loci D16S409 and D16S419 by using multipoint sibpair analysis (P less than 1.5x10(-5)). This region of the genome contains candidate genes which may be relevant to the pathogenic mechanism of inflammatory bowel diseases.

Association within twin pairs for a dichotomous trait

We propose an odds-ratio measure of twin association for a dichotomous trait. This odds ratio can be estimated without arbitrarily specifying an index twin and without estimating additional nuisance parameters. Tests of association and confidence intervals may be computed easily, in contrast to those proposed previously [Donner et al. (1995) Genet Epidemiol 12:267-277] for a correlation measure of association. For testing homogeneity of association in two samples of twins, monozygotic and dizygotic, we propose a large-sample test and an exact test, both based on the odds-ratio parameterization. Large-sample tests of homogeneity are slightly anticonservative when some cell counts are small, and the exact test may be preferred in these situations. We also propose a long-linear parameterization useful for modeling more complex data sets.

The asymmetry of P+ in bacterial reaction centers revealed by circular dichroism spectroscopy

The circular dichroism anisotropy, (AL-AR)/A, has been measured for the far-red absorption band of P+ in reaction centers of two purple bacteria (Rhodopseudomonas viridis and Rhodobacter sphaerides) and one green sulfur bacterium (Chlorobium tepidum). The anisotropy values for P960+ (Rps. virdis) at 1310 nm was found to be +(13 +/- 2) x 10(-4). The corresponding for P870+ (Rb. sphaeroides) at 1250 nm was +(11 +/- 1) x 10(-4), but for P840+ (C. tepdium) at 1160 nm the value was negative: -(27 +/- 2) x 10(-4). These results show that the configuration of the special pair in P840 is significantly different from the configuration in P870 and P960.

Non-11p constitutional chromosome abnormalities in Wilms' tumor patients

The incidence in Wilms' tumor patients of constitutional chromosome defects other than those involving the short arm of chromosome 11 was examined using data on 5,854 patients registered in the National Wilms Tumor Study. Trisomy 18 and Turner syndromes were found to occur at higher rates than expected based on chromosome surveys of newborns. Four patients were reported to have trisomy 18; all of these patients were over 5 years of age at the time of diagnosis of Wilms' tumor and none survived longer than six months. Four patients were reported to have Turner syndrome; these patients are currently doing well and have all survived at least 3 years following diagnosis. Two of the Turner patients and one of the trisomy 18 patients had horse-shoe kidneys; we speculate that this renal anomaly may contribute to the higher rates of tumor in these patients. No clear pattern was found among patients with other chromosome defects, although two patients had defects involving 2q37.

Multipoint linkage analysis using sib pairs: an interval mapping approach for dichotomous outcomes

I propose an interval mapping approach suitable for a dichotomous outcome, with emphasis on samples of affected sib pairs. The method computes a lod score for each of a set of locations in the interval between two flanking markers and takes as its estimate of trait-locus location the maximum lod score in the interval, provided it exceeds the prespecified critical value. Use of the method depends on prior knowledge of the genetic model for the disease only through available estimates of recurrence risk to relatives of affected individuals. The method gives an unbiased estimate of location, provided the recurrence risk are correctly specified and provided the marker identity-by-descent probabilities are jointly, rather than individually, estimated. I also discuss use of the method for traits determined by two loci and give an approximation that has good power for a wide range of two-locus models.

Robust multipoint linkage analysis: an extension of the Haseman-Elston method

The use of multiple markers, rather than a single marker, can increase the likelihood of detecting linkage to a locus underlying a quantitative trait. In this paper, the Haseman-Elston sibpair method is extended to include information from multiple markers. The result is a linear regression of the squared pair trait difference on the jointly estimated proportions of genes shared identical by descent at the two closest flanking marker loci. The results strengthen the theoretical motivation for the interval mapping technique proposed by Fulker and Cardon [1994: Am J Hum Genet 54:1092-1103] and extend the method to include information from multiple markers, account for a trait dominance component, and examine the region just outside that defined by the markers. Simulations show that modest increases in power and substantial decreases in bias of parameter estimates are obtained when identity-by-descent probabilities are jointly estimated. The regression relationship is also developed for other types of relative pairs.

Design and sample-size considerations in the detection of linkage disequilibrium with a disease locus

The presence of linkage disequilibrium between closely linked loci can aid in the fine mapping of disease loci. We investigate the power of several designs for sampling individuals with different disease genotypes. As expected, haplotype data provide the greatest power for detecting disequilibrium, but, in the absence of parental information to resolve the phase of double heterozygotes, the most powerful design samples only individuals homozygous at the trait locus. For rare diseases, such a scheme is generally not feasible, and we also provide power and sample-size calculations for designs that sample heterozygotes. The results provide information useful in planning disequilibrium studies.

Robust estimation of gene frequency and association parameters

Methods based on generalized estimating equations are proposed for estimation and testing of gene frequency and association parameters using family data. In the problems considered, a marginal model is used to estimate the gene frequency and association parameters specified in the marginal distributions of the individuals. These procedures are robust in the sense that consistent estimates of the parameters of interest and their standard errors are obtained even though the marginal model is not fully correctly specified. In addition, the methods are shown to have good efficiency when compared with maximum likelihood methods. Specific procedures for application of the methods to the cases of allele frequency estimation, testing of linkage and Hardy-Weinberg disequilibrium parameters, and testing for marker-disease association are outlined and illustrated with data examples.

Gene therapy of rat 9L gliosarcoma tumors by transduction with selectable genes does not require drug selection

9L rat glioma cells have been used as a model for brain tumor therapies. It has been reported that in vivo infection of 9L cells with a replication-defective retrovirus expressing the herpes simplex thymidine kinase gene resulted in decreased tumor formation following treatment with the antiviral drug ganciclovir. In the study reported here, rats were injected either intracerebrally or subcutaneously with 9L glioma cells expressing a chimeric hygromycin phosphotransferase-thymidine kinase fusion protein or with unmodified 9L cells. Tumor formation was decreased in the rats receiving modified cells, even in the absence of treatment with ganciclovir. Suppression of tumor growth was also observed with cells modified to express the intracellular selectable marker neomycin phosphotransferase. These results indicate that an intracellular selectable marker, in the absence of pharmacologic selection, can inhibit tumor growth of 9L cells. The demonstration that intracellular marker genes can negatively influence the survival of transplanted cells has important implications for in vivo studies that use genetically modified cells.

Power output of scallop adductor muscle during contractions replicating the in vivo mechanical cycle

Because measurements on isolated skeletal muscles are often made with limited knowledge of in vivo kinematics, predictions of mechanical performance during natural movements are subject to considerable uncertainties. We used information on the in vivo length cycle and phase of activation of the scallop adductor during swimming at 10 degrees C to design an in vitro contractile regime that replicated the natural cycle. Replicating the in vivo length cycle and stimulation regime resulted in power output during cyclic contractions that matched in vivo performance both qualitatively and quantitatively. When sinusoidal length changes were used instead of the natural length trajectory, the adductor muscle produced a similar average power output (approximately 30 W kg-1 at 1.9 Hz), but the distribution of power throughout the cycles was quite different. We examined the instantaneous force-velocity properties during cyclic contractions and found that the muscle operated on or near its isotonic force-velocity curve for only 30-40% of the time required for shortening. During sinusoidal length cycles, the force-velocity trajectory was quite different. We conclude that during cyclic contractions the isotonic force-velocity curve of skeletal muscle sets an approximate boundary to the force-velocity trajectory, but the shape of this trajectory, and thus the distribution of power output, depends on the pattern of length change.

Low-temperature spectroscopy of isolated FMO-protein and a membrane-free reaction center complex from the green sulfur bacteriumChlorobium tepidum

We have isolated the water-soluble BChla-protein (FMO-protein) from the greer sulfur bacteriumChlorobium tepidum by a new procedure involving a salt-wash of isolated membranes at alkaline pH. The absorption spectrum of the isolated FMO-protein at 77 K was compared with that of a reaction-center complex containing the FMO-protein (FMO-RC complex) isolated fromC. tepidum following the procedure of Feiler U, Nitsche W and Michel H (1992) Biochemistry 31: 2608-2614. Oxidation or illumination of the FMO-RC complex caused bleaching of a component with a maximum at 836 nm which was not present in the purified FMO-protein.

The formation and characterization of the in vitro polymeric aggregates of bacteriochlorophyllc homologs fromChlorobium limicola in aqueous suspension in the presence of monogalactosyl diglyceride

Artificial aggregates of bacteriochlorophyllc (BChlc) were formed in an aqueous medium in the presence of a lipid, monogalactosyl diglyceride (MGDG), and the optical properties of those aggregates were studied by absorption and circular dichroism (CD) mainly. Four BChlc homologs, ([E,E]BChlc F, [P,E]BChlc F, [E,M]BChlc F and [I,E]BChlc F), were isolated from the green photosynthetic bacteriumChlorobium limicola strain 6230. Above 0.0004%, MGDG induced a red-shift of the absorption maxima of BChlc aggregates. At 0.003% MGDG BChlc aggregates showed absorption maxima in the range of 724 to 745 (±3) nm with a shift of 12 to 24 (±3) nm depending on the homolog species. Four kinds of BChlc-MGDG aggregates showed characteristic CD spectra. [E,M]BChlc F gave rise to a CD spectrum similar to that of chlorosomes, while the other three gave spectra of opposite sign. These aggregates are sensitive to 1-hexanol treatment; in a saturating amount (0.85%) of 1-hexanol, all the homologs gave a monomer-like absorption spectrum peaking at 670nm. At an intermediate concentration (0.5%), [E,M]BChlc F showed an enhanced CD intensity, as observed in native chlorosomes. Resonance Raman spectra of the monomer-like BChlc samples indicated that the keto vibrational band at ca. 1640 cm(-1) was considerably weakened by the 0.85% 1-hexanol treatment, however the 1680 cm(-1) band characteristic of a free keto group did not appear. These results indicate that the artificial aggregates formed by purified BChlc homologs and MGDG are good models for studying chlorosomes structure.

Reminiscence about'Chloropseudomonas ethylicum' and the FMO-protein

In 1961 the green sulfur bacterium-containing mixed culture known as'Chloropseudomonas ethylicum' was brought to Brookhaven National Laboratory (USA) from Moscow State University (USSR). The water-soluble bacteriochlorophylla-protein (FMO-protein) was extracted, purified and characterized by absorption and circular dichroism spectroscopy, by X-ray crystallography and by primary structure determination.

The apolipoprotein E/CI/CII gene cluster and late-onset Alzheimer disease

The chromosome 19 apolipoprotein E/CI/CII gene cluster was examined for evidence of linkage to a familial Alzheimer disease (FAD) locus. The family groups studied were Volga German (VG), early-onset non-VG (ENVG; mean age at onset < 60 years), and late-onset families. A genetic association was observed between apolipoprotein E (ApoE) allele epsilon 4 and FAD in late-onset families; the epsilon 4 allele frequency was .51 in affected subjects, .37 in at-risk subjects, .11 in spouses, and .19 in unrelated controls. The differences between the epsilon 4 frequencies in affected subjects versus controls and in at-risk subjects versus controls were highly significant (standard normal deviate [ZSND]) = 7.37, P < 10(-9); and ZSND = 4.07, P < .00005, respectively). No association between the epsilon 4 allele and FAD was observed in the ENVG or VG groups. A statistically significant allelic association between epsilon 4 and AD was also observed in a group of unrelated subjects; the epsilon 4 frequency was .26 in affected subjects, versus .19 in controls (ZSND = 2.20, P < .03). Evidence of linkage of ApoE and ApoCII to FAD was examined by maximum-likelihood methods, using three models and assuming autosomal dominant inheritance: (1) age-dependent penetrance, (2) extremely low (1%) penetrance, and (3) age-dependent penetrance corrected for sporadic Alzheimer disease (AD). For ApoCII in late-onset families, results for close linkage were negative, and only small positive lod-score-statistic (Z) values were obtained (model 1, maximum Z[Zmax] = 0.61, recombination fraction [theta] = .30; model 2, Zmax = 0.47, theta = .20). For ApoE in late-onset kindreds, positive Z values were obtained when either allele frequencies from controls (model 1, Zmax = 2.02, theta = .15; model 2, Zmax = 3.42, theta = .05) or allele frequencies from the families (model 1, Zmax = 1.43, theta = .15; model 2, Zmax = 1.70, theta = .05) were used. When linkage disequilibrium was incorporated into the analysis, the Z values increased (model 1, Zmax = 3.17, theta = .23; model 3, Zmax = 1.85, theta = .20). For the ENVG group, results for ApoE and ApoCII were uniformly negative. Affected-pedigree-member analysis gave significant results for the late-onset kindreds, for ApoE (ZSND = 3.003, P = .003) and ApoCII (ZSND = 2.319, P = .016), when control allele frequencies were used but not when allele frequencies were derived from the families.

Some empirical properties of an all-relative-pairs linkage test

Olson and Wijsman [Genet Epidemiol 10:87-102, 1993] recently proposed a single test of linkage which combines information from different types of relative pairs in a pedigree. Relative-pair-type-specific regression parameters that relate the squared pair trait difference to the estimated number of marker genes shared identical by descent between the pair are estimated using generalized estimating equation methodology, then combined to give a single linkage test statistic. Questions remain concerning the small sample and robustness properties of this test statistic; these questions are addressed in the present paper using simulation. The test is substantially anti-conservative for samples with fewer than about ten families and are approximately valid for samples larger than about 15 families. In addition, the test appears robust in the presence of trait genotype by environment interaction, trait family-specific errors, a second major trait locus, and trait dominance. Surprisingly, the sibpair test was more powerful than the all-relative-pairs test for dominant traits with high heritability. Finally, adjusting for the presence of a marker known to be linked to one trait locus only marginally improves the power for detecting a second trait locus.

Testing the Hardy-Weinberg law across strata

The problem of testing the Hardy-Weinberg law when data are sampled from several populations with different allele frequencies is considered. An odds-ratio representation of disequilibrium is proposed. This ratio is assumed to be constant across strata, an assumption that seems more reasonable than that of previous authors of a constant difference in true and expected (under equilibrium) heterozygote proportions. A score-type test which optimally combines information from the separate strata is then derived using the theory of unbiased estimating equations. Simulations show that the new test has greater power than previously proposed tests when the disequilibrium ratio is constant across strata. The method is applied to glyoxalase genotype data from populations in India.

Self-esteem and counterfactual thinking

Two studies examined the relation between self-esteem and counterfactual thinking (consideration of "might-have-been" alternatives to reality). Ss imagined themselves in scenarios with another actor that resulted in either success or failure. Ss then "undid" the outcome by altering events that preceded the outcome. Following success, high self-esteem (HSE) Ss were more likely than low self-esteem (LSE) Ss to mutate their own actions. Following failure, LSE Ss were more likely than HSE Ss to mutate their own actions. Also, the structure of counterfactuals was influenced by outcome valence but not by self-esteem: Subtractive structures (in which antecedents are removed) were elicited by success, whereas additive structures (in which antecedents are added) were elicited by failure. The importance of the self and individual differences in self-esteem to counterfactual thinking is discussed.

Cancer in twins of Wilms tumor patients

We interviewed families of 71 patients registered in the National Wilms Tumor Study and identified as having a twin sibling. Questions concerning zygosity and the occurrence of congenital anomalies and other forms of cancer in the twins were asked. Of the 71 twin pairs, 35 were dizygotic, 31 were monozygotic, and 5 were of unknown zygosity. The only pair concordant for Wilms tumor was dizygotic, leading to a heritability estimate of zero. In a monozygotic pair, one twin was diagnosed with Wilms tumor and the other with medulloblastoma. The estimated relative risk of Wilms tumor and childhood cancer in the co-twin was 250 times and 10 times the population rate, respectively. Four discordant pairs had a family history of Wilms tumor, suggesting that the penetrance of the condition is not complete. Because of the small sample size, caution should be exercised in the interpretation of these results.

Diabetes increases excretion of urinary malonaldehyde conjugates in rats

The effect of streptozotocin-induced diabetes on the urinary excretion of thiobarbituric acid test-positive materials was examined. In diabetic rats, urinary excretion of thiobarbituric acid reactive substances was increased 5-fold over that in nondiabetic animals. High-performance liquid chromatography of urine samples revealed that five of the six fractions previously found to be increased in vitamin E deficiency [Lee, H.-S., Shoeman, D.W., and Csallany, A.S. (1992) Lipids 27, 124-128] were also significantly increased in streptozotocin-induced diabetes. The data suggest that a high level of oxidative stress is induced by uncontrolled diabetes in rats.

Self-esteem and counterfactual thinking

Two studies examined the relation between self-esteem and counterfactual thinking (consideration of "might-have-been" alternatives to reality). Ss imagined themselves in scenarios with another actor that resulted in either success or failure. Ss then "undid" the outcome by altering events that preceded the outcome. Following success, high self-esteem (HSE) Ss were more likely than low self-esteem (LSE) Ss to mutate their own actions. Following failure, LSE Ss were more likely than HSE Ss to mutate their own actions. Also, the structure of counterfactuals was influenced by outcome valence but not by self-esteem: Subtractive structures (in which antecedents are removed) were elicited by success, whereas additive structures (in which antecedents are added) were elicited by failure. The importance of the self and individual differences in self-esteem to counterfactual thinking is discussed.

Wilms' tumour and parental age: a report from the National Wilms' Tumour Study

Age distributions of parents at birth of patients registered in the National Wilms' Tumour Study were compared to those of the general population. An increasing incidence of sporadic Wilms' tumour with increasing paternal age was found, with a relative risk of 2.1 of tumour in children of fathers over 55 compared to children of fathers younger than 20. A similar effect for maternal age was found, with a relative risk of 1.4 in children of mothers over 40 compared to children of mothers younger than 20. The maternal age effect was much weaker among patients registered later in the study; in the later, more completely ascertained cohort, paternal age appears to be the major contributor to the parental age effect. Little difference in paternal age distribution was found between patients with bilateral and unilateral tumour and between male and female patients. In contrast, patients with reported associated congenital anomalies, patients with evidence of nephrogenic rests, and patients with early or late age-of-onset of tumour had parents who were, on average, substantially older than the remainder. These findings lend support to the idea that many Wilms' tumours result from new germline mutations. Further, the histologic composition of such tumours may be sufficiently distinct as to provide a valuable diagnostic indicator of the etiology of these tumours.

Contractile properties of the striated adductor muscle in the bay scallop Argopecten irradians at several temperatures

The isometric and isotonic contractile properties of the cross-striated adductor muscle of the bay scallop (Argopecten irradians) were measured in vitro at 10, 15 and 20 degrees C. The length at which twitch force was maximal as a function of the closed length in situ (L0/Lcl) averaged 1.38 +/− 0.01 (mean +/− S.E.M.) at 10 degrees C. This length is very close to the typical length at maximum gape during natural swimming at this temperature. Passive force was very low over the range of lengths measured here; at L0, passive force averaged approximately 0.08 N cm-2, or only 0.5% of the corresponding peak twitch force. The mean peak isometric twitch force (Ptw,max) at 10 degrees C was 21.43 +/− 0.68 N cm-2 (S.E.M.), and the ratio of peak twitch force to tetanic force (Ptw,max/P0) averaged 0.89 +/− 0.01. Temperature did not affect either twitch force (Ptw), once fatigue was taken into account, or Ptw,max/P0. In contrast, the time-related properties of twitch contractions (latent period, tL; time to peak tension, tPtw; and time from peak tension to half-relaxation, t50%R) were positively modified by temperature at all temperatures measured (Q10 &gt; 1.8). All three properties were more temperature-sensitive over the range 10–15 degrees C than over the range 15–20 degrees C. The force-velocity relationships of the striated adductor muscle were fitted to the hyperbolic-linear (HYP-LIN) equation. The force-velocity curves of the striated adductor muscle of the scallop were strongly influenced by temperature. Maximal velocity at zero force (Vmax), and therefore maximal power output, increased significantly with temperature. The Q10 over the temperature range 10–15 degrees C (1.42) was significantly lower than that over the range 15–20 degrees C (2.41). The shape of the force-velocity relationship, assessed through comparisons of the power ratio (Wmax/VmaxP0), was not influenced by temperature.

Linkage analysis of Alzheimer's disease with methods using relative pairs

Four relative-pair methods for detecting genetic linkage were applied to familial Alzheimer's disease data. Results obtained using an extended Haseman-Elston test and a weighted rank pairwise correlation test, which both use information from all relative pairs, were consistent with previously published likelihood results and appear to be more powerful than affected sib pair methods.

Linkage between quantitative trait and marker loci: methods using all relative pairs

Relative-pair methods for detection of linkage between a quantitative trait and a marker locus have been proposed by a number of authors [e.g., Haseman and Elston, Behav Genet 3-19, 1972; Amos and Elston, Genet Epidemiol 349-360, 1989]. However, development of tests of significance that combine information from different types of relative pairs has been hampered by the presence of correlations between relative pairs from the same pedigree. In this paper, the methodology of generalized estimating equations is used to provide an estimate of the robust covariance matrix of the estimates of the set of relative-pair-type-specific regression parameters. Using this matrix, an asymptotically most powerful test of linkage which optimally combines the information contained in the different types of relative pairs is constructed. This test requires optimal weights that depend on unknown values of heritability and recombination fraction to be chosen a priori. However, simulations show that, in the regions of recombination fraction and heritability of practical interest, the power of the test does not depend strongly on the assumptions made when choosing the optimal weights; as a result, weights that depend only on the number of each type of relative pair and the variability of the marker identity-by-descent probabilities work well in practice. In addition, an approximation to the regression model leads to a simple approach to testing linkage in which only a single regression parameter is estimated from data containing different types of relative pairs. The resulting test is slightly less powerful than the test described above, but its computational simplicity and lack of dependence on a priori weighting schemes suggest potential usefulness in large linkage studies.

Dietary guar gum halts further renal enlargement in rats with established diabetes

Guar gum, a dietary fiber known to improve glucose tolerance, was fed to rats with established diabetes to determine its effect on renal enlargement and microalbuminuria. Diabetic rats were fed a modified AIN-76A (basal) diet for 4 wk, at which time half the rats continued to receive the same basal diet (DB-BA group) and half were switched to a 5% guar gum diet (DB-GG group). Nondiabetic rats fed the basal diet served as controls (NRL group). After 8 additional weeks the animals were killed. Glycated hemoglobin, a measure of long-term blood glucose control, was 14.4% in the DB-BA group and 12.4% in the DB-GG group, a statistically significant difference (P < 0.05). Kidney weight of the DB-BA group (3.51 g) was significantly greater than that of the DB-GG group (2.76 g) (P < 0.05). Eight weeks after induction of diabetes, 24-h urinary albumin excretion was highest in the DB-BA group and lowest in the NRL group; excretion in the DB-GG group (4 wk of guar feeding) was intermediate. However, by 12 wk no differences in albumin excretion among the groups were apparent. These results suggest that guar gum may be useful for slowing the progression of diabetic nephropathy and that guar gum deserves further study in this regard.

Aggregation of bacteriochlorophyll c homologs to dimers, tetramers, and polymers in water-saturated carbon tetrachloride

Three homologs of BChl c, 2-(R)-(1-hydroxyethyl)-4-n-propyl-5-ethyl-farnesyl BChl c (PEF-BChl c), 2-(R)-(1-hydroxyethyl)-4-ethyl-5-ethyl-farnesyl BChl c (EEF-BChl c), and 2-(S)-(1-hydroxyethyl)-4-isobutyl-5-methyl/ethyl-farnesyl BChl c (iBM/EF-BChl c), formed aggregates in water-saturated carbon tetrachloride (H2O-satd CCl4). The water content was about 100 times higher than that of the dried CCl4 previously used. Absorption spectra were recorded for 8 concentrations for the three homologs of BChl c and were deconvoluted in terms of standard spectra of monomer, dimer, tetramer and polymer (747-nm aggregate, Olson and Pedersen (1990) Photosynthe Res 25: 25). PEF- and EEF-BChl c formed dimers (680 nm maximum) and tetramers (705-710 nm maximum), but iBM/EF-BChl c formed polymers. Inhibition of dimer formation by water faciliated the study of the initial stages of the polymerization of BChl c. When the logarithm of polymer concentration was plotted versus the logarithm of the monomer concentration for iBM/EF-BChl c, the initial slope was 30±10 and indicated the cooperation of 20-40 BChl c molecules to form a polymer from a seed. Circular dichroism spectra of the polymers with positive and negative bands at 743 and 760 nm, respectively, were similar to those for chlorosomes (Brune et al. (1990) Photosynth Res 24: 253).

Mechanical performance of scallop adductor muscle during swimming

Mechanical performance of skeletal muscle has long been the subject of intense interest, but the details of in vivo performance of individual skeletal muscles during normal locomotion remain largely unknown. Performance in vitro has been described with considerable precision under simplified loading conditions. The force production and shortening velocity of most muscles, however, probably change continuously during natural movements. Therefore, modelling in vivo performance on the basis of in vitro contractile properties is subject to large degrees of uncertainty. Designing in vitro experiments that effectively examine the limits of mechanical performance requires increasing knowledge of precisely how muscles are used during normal movements. We report here measurements of the mechanical performance of the adductor muscle in scallops during jet-propulsion swimming. Swimming in scallops is powered solely by the striated portion of the single adductor muscle. Exploiting this simple locomotor morphology with simultaneous high-resolution measurements of pressure and flow rate, we have recorded nearly instantaneous measurements of the performance of a single skeletal muscle during normal locomotion.

Localization of the peripheral-type benzodiazepine binding site to mitochondria of human glioma cells

Subcellular fractionation was performed on human U251 glioblastoma cultures. In all subcellular fractions, the binding of the peripheral benzodiazepine ligand, [3H]PK 11195, correlated with the specific activity of monoamine oxidase (r = 0.95, p less than 0.001) and succinate dehydrogenase (r = 0.93, p less than 0.001), two mitochondrial enzymes. The specific activity of plasma membrane and nuclear markers correlated poorly with the presence of PK 11195 binding sites. These data support the mitochondrion as the primary location of peripheral-type benzodiazepine binding sites (PBBS) in human glioma cells. Mitochondria-rich preparations were then assayed for [3H]Ro5-4964 binding. Six nM [3H]Ro5-4964 failed to specifically bind to human U251 mitochondria, but bound vigorously to mitochondria from rat C6 glioma. These data indicate that the low affinity of Ro5-4864 for PBBS in human glioma cells compared to those in rat is due to interspecies receptor variation rather than impaired drug transport into human cells.

Psychological Barriers to Behavior Change: How to indentify the barriers that inhibit change

Adopting a healthy lifestyle often requires changing patterns of behavior. This article describes three categories of psychological barriers to behavior change: those that prevent the admission of a problem, those that interfere with initial attempts to change behavior, and those that make long-term change difficult. Strategies are identified that family physicians can use to overcome the barriers.

4-Isobutyl homologs of farnesyl bacteriochlorophyll c in carbon tetrachloride

Absorption (ABS) and circular dichroism (CD) spectra were recorded for 3 concentrations (2.3, 19 and ca. 75 μM) of 4-isobutyl homologs. Monomer spectra were the same as those for 4-n-propyl-5-ethyl farnesyl bacteriochlorophyll c. Pure polymer spectra were obtained by subtracting the 2.3-μM spectra appropriately scaled from the ca. 75-μM spectra. The polymer showed an ABS peak at 742 nm and a CD trough at ca. 742 nm. These properties are in harmony with the aggregate model proposed by Smith KM, Kehrs LA and Fajer J (1983, J Am Chem Soc 105: 1387-1389). A log-logplot of absorbance at 742 nm vs. monomer concentration could be fitted by a straight line of slope 1.6.