Deletion of Coagulation Factor IX Compromises Bone Mass and Strength: Murine Model of Hemophilia B (Christmas Disease)

Osteopenia and osteoporosis have increasingly become a recognized morbidity in those persons with hemophilia (PwH) receiving inadequate prophylactic clotting factor replacement. Animal models can control or eliminate genetic and environmental factors and allow for invasive testing not clinically permissible. Here, we describe the skeletal phenotype of juvenile and adult male mice with a genetically engineered deficiency in coagulation factor IX (FIX KO). Although the somatic growth of FIX KO mice matched that of their wild-type (WT) littermates at 10 and 20 weeks of age, the FIX KO mice displayed reduced bone mineral density (BMD), reduced cortical and cancellous bone mass, and diminished whole bone fracture resistance. These findings coupled with parallel observations in a murine model of hemophilia A (FVIII deficiency) point to an effector downstream of the coagulation cascade that is necessary for normal skeletal development. Further study of potential mechanisms underlying the bone disease observed in rare clotting factor deficiency syndromes may lead to new diagnostic and therapeutic insights for metabolic bone diseases in general.

Genetic Burden Contributing to Extremely Low or High Bone Mineral Density in a Senior Male Population From the Osteoporotic Fractures in Men Study (MrOS)

Worldwide, one in five men aged over 50 years will experience osteoporosis or a clinical bone fracture, with a greater fracture-related mortality rate than women. However, the genetic etiology of osteoporosis in men is still poorly understood. We aimed to identify the genetic variants and candidate genes associated with extremely low or high BMD for a better understanding of the biology underlying low bone density that may point to potential therapeutic targets for increasing bone mass. Subjects from the Osteoporotic Fractures in Men Study (MrOS) cohort were evaluated by age and BMI-adjusted total hip BMD. Those with BMD values 3 SDs away from the mean were selected and the remaining individuals whose adjusted BMD ranked at the highest or lowest 100 were included. Men with the lowest adjusted BMD (N = 98) and highest adjusted BMD (N = 110) were chosen for exome sequencing. Controls (N = 82) were men of Northern and Western European descent from the US Utah population of the 1000 Genomes Project. Fisher's exact test was performed to compare low- or high-BMD subjects with controls for single-gene associations. Additionally, sets of candidate genes causative of heritable disorders of connective tissue, including osteogenesis imperfecta (OI) and Ehlers-Danlos syndrome (EDS), were grouped for multigene and mutation burden analyses. No single-gene associations with rare variants were found for either the low BMD group (33 genes) or high BMD group (18 genes). In the group of OI genes, we detected a significant threefold increased accumulation of rare variants in low-BMD subjects compared with controls (p = 0.009). Additionally, genes associated with EDS had a twofold increased frequency in low-BMD subjects compared with controls (p = 0.03). These findings reveal a rare variant burden in OI and EDS disease genes at low BMD, which suggests a potential gene-panel approach to screen for multivariant associations in larger cohorts. © 2019 The Authors. JBMR Plus published by Wiley Periodicals, Inc. on behalf of American Society for Bone and Mineral Research.

Neonatal estrogen exposure results in biphasic age-dependent effects on the skeletal development of male mice

Peak bone mass, one of the most important predictors for fracture risk later in life, is attained during puberty and adolescence and influenced by neonatal and pubertal sex-specific gonadal hormones and GH-IGF-I secretion patterns. This study examined the effects of brief neonatal estrogen (NE) exposure on growth and skeletal development in C57BL/6J mice. A single injection of 100-μg estradiol or vehicle was administered on the first day of life. Growth parameters were monitored and skeletal phenotyping performed at 16 weeks in female mice and at 4 and 16 weeks in male mice. NE exposure negatively impacted adult femoral length in both sexes, but adult body weight, areal bone density, and bone strength in female mice were unaffected. In contrast, somatic growth was attenuated in estrogen-exposed male mice throughout the study period. At the prepubertal time point, the estrogen-exposed males exhibited higher bone mineral density, cortical volume, and cortical thickness compared with controls. However, by the time of peak bone mass acquisition, the early skeletal findings had reversed; estrogen-exposed mice had lower bone density with reduced cross-sectional area, cortical volume, and cortical thickness, resulting in cortical bones that were less resistant to fracture. NE exposure also resulted in reduced testicular volume and lower circulating IGF-I. Male mice exposed to estrogen on the first day of life experience age-dependent changes in skeletal development. Prepubertal animals experience greater endocortical bone acquisition as a result of estrogen exposure. However, by adulthood, continued developmental changes result in overall reduced skeletal integrity.

Distinct actions of akt1 on skeletal architecture and function

Skeletal integrity is dependent on the coordinated actions of bone-forming osteoblasts and bone-resorbing osteoclasts, which recognize and respond to multiple environmental inputs. Here we have studied the roles in bone development and growth of Akt1 and Akt2, two closely related signaling proteins, by evaluating mice lacking either of these enzymes. Global deficiency of Akt1 but not Akt2 caused a reduction in whole body and femoral bone mineral density, in femoral cortical thickness and volume, and in trabecular thickness in both males and females when measured at 20-weeks of age, which was reflected in diminished femoral resistance to fracture. Haplo-deficiency of Akt1 in male mice also decreased femoral cortical and trabecular skeletal parameters, and reduced bone strength. Cell-based studies showed that genetic Akt1 deficiency diminished the rate of proliferation of osteoblast progenitors and impaired osteoclast differentiation in primary culture but that loss of Akt2 did not. Our results demonstrate differential effects of Akt1 and Akt2 on skeletal maturation and architecture through actions on both osteoblast and osteoclast precursors.

Regulation of lean mass, bone mass, and exercise tolerance by the central melanocortin system

Signaling via the type 4-melanocortin receptor (MC4R) is an important determinant of body weight in mice and humans, where loss of function mutations lead to significant obesity. Humans with mutations in the MC4R experience an increase in lean mass. However, the simultaneous accrual of fat mass in such individuals may contribute to this effect via mechanical loading. We therefore examined the relationship of fat mass and lean mass in mice lacking the type-4 melanocortin receptor (MC4RKO). We demonstrate that MC4RKO mice display increased lean body mass. Further, this is not dependent on changes in adipose mass, as MC4RKO mice possess more lean body mass than diet-induced obese (DIO) wild type mice with equivalent fat mass. To examine potential sources of the increased lean mass in MC4RKO mice, bone mass and strength were examined in MC4RKO mice. Both parameters increase with age in MC4RKO mice, which likely contributes to increases in lean body mass. We functionally characterized the increased lean mass in MC4RKO mice by examining their capacity for treadmill running. MC4R deficiency results in a decrease in exercise performance. No changes in the ratio of oxidative to glycolytic fibers were seen, however MC4RKO mice demonstrate a significantly reduced heart rate, which may underlie their impaired exercise performance. The reduced exercise capacity we report in the MC4RKO mouse has potential clinical ramifications, as efforts to control body weight in humans with melanocortin deficiency may be ineffective due to poor tolerance for physical activity.

Congenic mice provide in vivo evidence for a genetic locus that modulates intrinsic transforming growth factor β1-mediated signaling and bone acquisition

Osteoporosis, the most common skeletal disorder, is characterized by low bone mineral density (BMD) and an increased risk of fragility fractures. BMD is the best clinical predictor of future osteoporotic fracture risk, but is a complex trait controlled by multiple environmental and genetic determinants with individually modest effects. Quantitative trait locus (QTL) mapping is a powerful method for identifying chromosomal regions encompassing genes involved in shaping complex phenotypes, such as BMD. Here we have applied QTL analysis to male and female genetically-heterogeneous F(2) mice derived from a cross between C57BL/6 and DBA/2 strains, and have identified 11 loci contributing to femoral BMD. Further analysis of a QTL on mouse chromosome 7 following the generation of reciprocal congenic strains has allowed us to determine that the high BMD trait, which tracks with the DBA/2 chromosome and exerts equivalent effects on male and female mice, is manifested by enhanced osteogenic differentiation of mesenchymal stem cells (MSCs) in vitro and by increased growth of metatarsal bones in short-term primary culture. An insertion/deletion DNA polymorphism in Ltbp4 exon 12 that causes the in-frame removal of 12 codons in the DBA/2-derived gene maps within 0.6 Mb of the marker most tightly linked to the QTL. LTBP4, one of four paralogous mouse proteins that modify the bioavailability of the transforming growth factor β (TGF-β) family of growth factors, is expressed in differentiating MSC-derived osteoblasts and in long bones, and reduced responsiveness to TGF-β1 is observed in MSCs of mice homozygous for the DBA/2 chromosome 7. Taken together, our results identify a potential genetic and biochemical relationship between decreased TGF-β1-mediated signaling and enhanced femoral BMD that may be regulated by a variant LTBP4 molecule.

Rare coding variants in ALPL are associated with low serum alkaline phosphatase and low bone mineral density

Alkaline phosphatase (ALP) plays an essential role in the regulation of tissue mineralization, and its activity is highly heritable. Guided by genetic associations discovered in a murine model, we hypothesized a role for rare coding variants in determining serum ALP level and bone mineral density (BMD) in humans. We sequenced the coding regions of the ALP gene (ALPL) in men with low and normal serum ALP activity levels. Single-nucleotide ALPL variants, including 19 rare nonsynonymous variants (minor allele frequency <1%), were much more frequent among the low ALP group (33.8%) than the normal group (1.4%, p = 1 × 10(-11)). Within the low ALP group, men with a rare, nonsynonymous variant had 11.2% lower mean serum ALP (p = 3.9 × 10(-4)), 6.7% lower BMD (p = 0.03), and 11.1% higher serum phosphate (p = 0.002) than those without. In contrast, common nonsynonymous variants had no association with serum ALP, phosphate, or BMD. Multiple rare ALPL coding variants are present in the general population, and nonsynonymous coding variants may be responsible for heritable differences in mineralization and thus BMD.

Perioperative Parathyroid Hormone Levels in Thyroid Surgery

OBJECTIVE

Perioperative hypocalcemia from temporary parathyroid gland dysfunction is common after thyroid surgery. No reliable cutoff values for parathyroid hormone (PTH) and the subsequent possibility of developing hypocalcemia exist. The purpose of this study is to determine a criterion for predicting hypocalcemia based on different PTH levels as cutoff values.

STUDY DESIGN

Retrospective chart review.

METHODS

A centralized database of intraoperative PTH levels was analyzed. PTH values approximately 10 minutes after excision of the thyroid gland and in the recovery room were obtained; serial ionized calcium levels were also analyzed. PTH values were then compared using chi-square analysis with significance defined as P < .05. A receiver operator characteristic (ROC) curve was also constructed to define sensitivities and specificities of different PTH levels as potential cutoff values.

RESULTS

Eighty patients were identified meeting the study criteria between January 1999 and February 2005. Fourteen of the 80 (17.5%) patients became hypocalcemic during the hospital stay; none experienced permanent hypocalcemia. Patients who became hypocalcemic during their hospitalization were more likely to have a PTH level below 15 pg/mL (P < .01). Patients with a PTH level less than 15 pg/mL were more likely to develop hypocalcemia (P < .01). Finally, an ROC curve was constructed, allowing the surgeon to determine acceptable sensitivities and specificities and various PTH cutoff values.

CONCLUSION

Low perioperative PTH levels significantly correlate with the presence of postoperative hypocalcemia but cannot be used to predict it. Using the ROC curve allows different chosen cutoff values to predict hypocalcemia with varying sensitivity and specificity.

Human ALOX12, but not ALOX15, is associated with BMD in white men and women

The Alox15 gene was recently identified as a negative regulator of peak BMD in mice. Polymorphisms in human ALOX12, but not ALOX15, were significantly associated with spine BMD in white men and women, suggesting that ALOX12 may contribute to normal variation in BMD.

INTRODUCTION

Osteoporosis is a complex disease with both genetic and environmental risk factors. A major determinant of osteoporosis is peak BMD, which is a highly heritable trait. Recently, the arachidonate 15-lipoxygenase (Alox15) gene was identified as a negative regulator of peak BMD in mice.

MATERIALS AND METHODS

To assess the contribution of lipoxygenase genes to normal BMD variation in healthy white men and women, we performed population- and family-based association studies of two arachidonate lipoxygenase genes: ALOX15, which is the human homolog of mouse Alox15, and ALOX12, which is functionally similar to Alox15. Single nucleotide polymorphisms (SNPs) distributed across the two genes were genotyped. BMD was measured at the femoral neck and lumbar spine in 411 men 18-61 years of age and 1291 premenopausal women 20-50 years of age.

RESULTS

Moderate evidence of association was found between spine BMD and six SNPs in the ALOX12 gene in both men and women (p = 0.0052-0.050). Furthermore, the most common SNP haplotype in ALOX12 showed evidence of significant association with high spine BMD in men (p = 0.0083), whereas the second most common haplotype was associated with high spine BMD in women (p = 0.0081).

CONCLUSIONS

Polymorphisms in the ALOX12 gene may contribute to normal variation in spine BMD.

Regulation of bone mass in mice by the lipoxygenase gene Alox15

The development of osteoporosis involves the interaction of multiple environmental and genetic factors. Through combined genetic and genomic approaches, we identified the lipoxygenase gene Alox15 as a negative regulator of peak bone mineral density in mice. Crossbreeding experiments with Alox15 knockout mice confirmed that 12/15-lipoxygenase plays a role in skeletal development. Pharmacologic inhibitors of this enzyme improved bone density and strength in two rodent models of osteoporosis. These results suggest that drugs targeting the 12/15-lipoxygenase pathway merit investigation as a therapy for osteoporosis.

Mapping quantitative trait loci that influence femoral cross-sectional area in mice

Size and shape are critical determinants of the mechanical properties of skeletal elements and can be anticipated to be highly heritable. Moreover, the genes responsible may be independent of those that regulate bone mineral density (BMD). To begin to identify the heritable determinants of skeletal geometry, we have examined femoral cross-sectional area (FCSA) in male and female mice from two inbred strains of mice with divergent FCSA (C57BL/6 [B6] and DBA/2 [D2]), a large genetically heterogeneous population (n = 964) of B6D2F2 mice and 18 BXD recombinant inbred (RI) strains derived from their F2 cross. Femora were harvested from 16-week-old mice and FCSA (bone and marrow space enclosed within the periosteum) was measured at the midshaft by digital image analysis. In all mouse populations examined, FCSA was positively correlated with body weight and weight-corrected FCSA (WC-FCSA) values were normally distributed in the BXD-RI and F2 populations, suggesting polygenic control of this trait. Genome-wide quantitative trait locus (QTL) analysis of the B6D2F2 population revealed regions on four different chromosomes that were very strongly linked to WC-FCSA (chromosomes 6, 8, 10, and X) in both genders. Evidence of gender-specific genetic influences on femoral geometry was also identified at three other chromosomal sites (chromosomes 2, 7, and 12). Supporting evidence for the WC-FCSA QTLs on chromosomes 2, 7, 8, 10, and 12 also was present in the RI strains. Interestingly, none of these WC-FCSA QTLs were identified in our previous QTL analysis of whole body BMD in the same B6D2F2 population. Thus, the genetic determinants of bone size appear to be largely, if not entirely, distinct from those that regulate BMD attainment. The identification of the genes responsible for geometric differences in bone development should reveal fundamentally important processes in the control of skeletal integrity.

Genetic regulation of bone mineral density in mice

Peak bone mass is a major determinant of risk of osteoporotic fracture. Family and twin studies have found a strong genetic component to the determination of bone mineral density (BMD). However, BMD is a complex trait whose expression is confounded by environmental influences and polygenic inheritance. The number, locations and effects of the individual genes contributing to natural variation in this trait are all unknown. The extreme difficulty of dissecting out environmental factors from genetic ones in humans has motivated the investigation of animal models. Genetically distinct animal strains raised under strict environmental control are critical tools for defining genetic regulation. The availability of inbred strains, combined with its relative fecundity, has established the mouse as the best model system for the study of mammalian genetics and physiology. Importantly, genes identified in murine analyses can usually be readily mapped to particular human chromosomal regions because of the high degree of synteny that exists between the mouse and human genomes. We employed quantitative trait locus (QTL) analysis to examine peak BMD in 24 recombinant inbred (RI) mouse strains, derived from a cross between C57BL/6 (B6) and DBA/2 (D2) progenitors (BXD RI). The distribution of BMD values among these strains clearly indicated the presence of strong genetic influences, with an estimated narrow sense heritability of 35%. The differences in peak whole body BMD in the BXD strains were integrated with a large database of genetic markers previously defined in the RI BXD strains to generate chromosome map sites for QTL locations. This QTL analysis provisionally identified a number of chromosomal sites linked to BMD. In the second phase of our BMD QTL mapping efforts, we used three independent mouse populations (all derived from B6 and D2 progenitor strains) to confirm and narrow the genetic locations of 4 QTLs (on chromosomes 1, 2, 4, and 11) that strongly influence the acquisition of peak BMD in mice. Using a novel, fine-mapping approach (recombinant inbred segregation testing), we have succeeded in narrowing two of the BMD-related chromosomal regions and in the process eliminated a number of candidate genes. The homologous regions in the human genome for each of these murine QTLs have been identified in recent human genetic studies. In light of this, we believe that findings in mice should aid in the identification of specific candidate genes for study in humans.

Gender specificity in the genetic determinants of peak bone mass

Peak bone mass is a major determinant of osteoporotic fracture risk. Gender differences in peak bone mass acquisition are well recognized in humans and may account for a substantial share of the increased prevalence of fragility fractures in women compared with men. Skeletal development is regulated by both heritable and environmental factors. Experimental animal models provide a means to circumvent complicating environmental factors. In this study we examined the heritability of peak bone mineral density (BMD) in genetically distinct laboratory mouse strains raised under strict environmental control and sought to identify genetic loci that may contribute to gender differences in this skeletal phenotype. Peak whole body BMD of male and female mice from a panel of 18 recombinant inbred (RI) strains derived from a cross between C57BL/6 and DBA/2 progenitors (BXD) was measured by dual-energy X-ray absorptiometry (DXA). A highly significant relationship existed between body weight and BMD in the BXD RI mice (r2 = 0.25; p = 1 x 10(-43)). To allow for comparison between male and female RI strains, whole body BMD values were corrected for the influence of body weight. The distribution of weight-corrected BMD (WC-BMD) values among the strains indicated the presence of strong genetic influences in both genders, with an estimated narrow sense heritability of 45% and 22% in male and female mice, respectively. Comparison of RI strain results by two-way analysis of variance (ANOVA) revealed a significant strain-by-gender interaction (F1,17,479 = 6.13; p < 0.0001). Quantitative trait locus (QTL) analysis of the BXD RI strain series provisionally identified nine chromosomal sites linked to peak bone mass development in males and seven regions in females. In two cases, the provisional chromosomal loci were shared between genders, but in most cases they were distinct (five female-specific QTLs and six male-specific QTLs). QTL analysis of a genetically heterogeneous F2 population derived from the B6 and D2 progenitor strains provided additional support for the gender specificity of two loci. A significant phenotype-genotype correlation was only observed in male F2 mice at microsatellite marker D7Mit114 on chromosome 7, and a correlation at D2Mit94 on chromosome 2 was only observed in female F2 mice. The present data highlight the important role of gender in the genetic basis of peak bone mass in laboratory mice. Because the male phenotype is associated with considerable fracture risk reduction, an elucidation of the nature of that effect could provide the basis for novel diagnostic, preventative, or therapeutic approaches.

In silico mapping of complex disease-related traits in mice

Experimental murine genetic models of complex human disease show great potential for understanding human disease pathogenesis. To reduce the time required for analysis of such models from many months down to milliseconds, a computational method for predicting chromosomal regions regulating phenotypic traits and a murine database of single nucleotide polymorphisms were developed. After entry of phenotypic information obtained from inbred mouse strains, the phenotypic and genotypic information is analyzed in silico to predict the chromosomal regions regulating the phenotypic trait.

Molecular epidemiologic features and antimicrobial susceptibility profiles of various ribotypes of Pseudomonas aeruginosa isolated from humans and ruminants

OBJECTIVES

To assess automated ribotyping for characterization of Pseudomonas aeruginosa isolates and to identify their type prevalence and geographic distribution.

SAMPLE POPULATION

39 human and 56 ruminant P aeruginosa isolates.

PROCEDURES

Isolates were identified by use of bacteriologic techniques and automated Pvull-based ribotyping. Susceptibility to antimicrobials was tested in vitro. Data were analyzed for index of discrimination; prevalence ratio; geographic distribution of ribotypes found only in humans, only in cows, or only in goats (single-host ribotypes); and geographic distribution of ribotypes found in humans and ruminants (multihost ribotypes).

RESULTS

All isolates were typeable (45 ribotypes, 35 single-host ribotypes). Ribotyping index of discrimination was 0.976. More isolates (45.3%) than expected yielded multihost ribotypes (22% of all ribotypes). Although 8.6% of single-host ribotypes were found in 4 or more isolates, 60% of multihost ribotypes were found in 4 or more isolates. Ninety percent of multihost ribotypes were isolated from different geographic areas, whereas 3.0% of single-host ribotypes were isolated from different geographic areas. All ruminant isolates were susceptible to gentamicin and polymyxin B. In contrast, antibiogram profiles differed for human isolates from different geographic areas. Susceptibility to antimicrobials differentiated 6 isolates not distinguished by ribotyping.

CONCLUSIONS AND CLINICAL RELEVANCE

Automated ribotyping with Pvull discriminated more isolates than in vitro antimicrobial susceptibility. In combination, both tests provided more information than either test alone. Given the greater prevalence and geographic distribution of multihost ribotypes, immunocompromised humans and lactating ruminants may have a greater risk for disease if exposed to multihost P aeruginosa ribotypes, compared with single-host ribotypes.

Phenotypic characterization of mice bred for high and low peak bone mass

In humans, peak bone mineral density (BMD) is a highly heritable trait and a strong determinant of subsequent osteoporotic fracture risk. To identify the genetic factors responsible for variation in peak BMD, investigators have turned to animal models. In this study we examined the heritability of BMD acquisition and characterized differences in skeletal geometry, histomorphometry, and biomechanical competence between two lines of mice artificially selected for extremes of peak whole body BMD. F2 progeny from a cross between C57BL/6 and DBA/2 inbred strains was used as the foundation population to develop lines selected for either high or low BMD. Whole body BMD was measured by dual-energy X-ray absorptiometry (DXA). By the third generation of selection, highest-scoring BMD (HiBMD) mice exhibited 14% greater peak BMD than lowest-scoring BMD (LoBMD) mice. The mean realized heritability of peak BMD was 36%. Femoral shaft cortical area and thickness and vertebral cancellous bone volume (BV) were significantly greater (16-30%) in the HiBMD line compared with the LoBMD line. Mean cancellous bone formation rates (BFRs) were 35% lower in HiBMD mice compared with LoBMD mice. Failure load and stiffness in the femoral shaft, femoral neck, and L6 vertebrae were all substantially greater (by 25-190%) in HiBMD mice. Thus, these divergently selected murine lines serve to illustrate some of the means by which genetic mechanisms can affect skeletal structure and remodeling. Identification of the individual genes influencing peak BMD in this experimental system will likely reveal some of the genetic determinants of overall bone strength.

Quantitative trait loci affecting peak bone mineral density in mice

Peak bone mass is a major determinant of risk of osteoporotic fracture. Family and twin studies have found a strong genetic component to the determination of bone mineral density (BMD). However, BMD is a complex trait whose expression is confounded by environmental influences and polygenic inheritance. The number, locations, and effects of the individual genes contributing to natural variation in this trait are all unknown. Experimental animal models provide a means to circumvent complicating environmental factors, and the development of dense genetic maps based on molecular markers now provides opportunities to resolve quantitative genetic variation into individual regions of the genome influencing a given trait (quantitative trait loci, QTL). To begin to identify the heritable determinants of BMD, we have examined genetically distinct laboratory mouse strains raised under strict environmental control. Mouse whole-body bone mineral content by dual-energy X-ray absorptiometry (DXA) correlated strongly with skeletal calcium content by ashing, and peak whole-body BMD by DXA in female mice occurred at approximately 80-90 days of age. We therefore determined mean body weight and peak whole body BMD values in 12-week-old female mice from a panel of 24 recombinant inbred (RI) BXD strains, derived from a cross between C57BL/6 and DBA/2 progenitors. The distribution of body weight and BMD values among the strains clearly indicated the presence of strong genetic influences on both of these traits, with an estimated narrow sense heritability of 60% and 35%, respectively. The patterns of differences in body weight and peak whole body BMD in the BXD strains were then integrated with a large database of genetic markers previously defined in the RI BXD strains to generate chromosome map sites for QTL. After correction for redundancy among the significant correlations, QTL analysis of the BXD RI strain series provisionally identified 10 chromosomal sites linked to peak bone mass development in the female. Several of the identified sites map near genes encoding hormones, structural proteins, and cell surface receptors that are intricately involved in skeletal homeostasis. Four QTL for body weight were also identified. One of these loci was also strongly linked to inherited variation in BMD. This finding suggests that body weight and peak BMD may be influenced by linked genes or perhaps by common genes with pleiotropic effects. Our phenotyping in the RI BXD strains has allowed us to map a number of specific genetic loci strongly related to the acquisition of peak BMD. Confirmation of these findings will likely result in the understanding of which genes control skeletal health.

Consumer reaction to healthcare advertising

How do consumers view healthcare advertising? This question, along with many others, was addressed in a national survey conducted by Market Strategies for The Alliance For Healthcare Strategy And Marketing, and presented during The Alliance's annual advertising and promotion conference last June.

Studies of the continuing susceptibility of group A streptococcal strains to penicillin during eight decades

BACKGROUND

In view of the widespread use of penicillin for >50 years for the treatment of group A streptococcal infections, we examined the question of whether there has been a change in susceptibility to penicillin in group A streptococcal strains collected during a span of 80 years (1917 to 1997).

METHODS

One hundred thirty-three group A streptococcal strains collected during 80 years were tested for changes in penicillin susceptibility. Three tests were used: (1) the microtiter broth minimal inhibitory concentration (MIC); (2) the minimal bactericidal concentration (MBC); and (3) the penicillin E strip MIC.

RESULTS

The results indicate there has been no change in the susceptibility to penicillin in these group A streptococci during the past 80 years. The microtiter broth MIC90 for the oldest strains (0.032 microg/ml) was not significantly different from those collected most recently (0.032 microg/ml); there is no statistical difference between the raw MIC data for the four collection periods (P=0.468, analysis of variance on ranks).

CONCLUSIONS

There has been no change in the susceptibility of group A streptococci during this time in spite of well-documented cases of penicillin resistance in other Gram-positive organisms and despite recognized resistance of group A streptococci to other antibiotics.

Alcohol-induced bone disease: impact of ethanol on osteoblast proliferation

The habitual consumption of even moderate quantities of alcohol (1 to 2 drinks/day) is clearly linked with reduced bone mass (osteopenia). Biochemical and histological evaluation of patients with alcoholic bone disease reveal a marked impairment in bone formation in the face of relatively normal bone resorption. Experiments using well-defined osteoblastic model systems indicate that the observed reductions in bone formation result from a direct, antiproliferative effect of ethanol on the osteoblast itself. As bone remodeling and mineralization are dependent on osteoblasts, it follows that the deleterious effect of alcohol on these cells would result in slowed bone formation, aberrant remodeling of skeletal tissue and, ultimately, osteopenia and fractures. The skeletal consequences of alcohol intake during adolescence, when the rapid skeletal growth ultimately responsible for achieving peak bone mass is occurring, may be especially harmful. The specific subcellular mechanisms whereby ethanol inhibits cell proliferation are, as yet, unknown. During the last few years, attention has shifted from nonspecific membrane perturbation effects to actions on certain signaling proteins. Specifically, there is increasing evidence that ethanol may exert significant effects on transmembrane signal transduction processes that constitute major branches of cellular control mechanisms. At present, abstinence is the only effective therapy for alcohol-induced bone disease. An improved understanding of the pathogenesis of alcohol-induced bone disease may eventually result in alternative therapeutic avenues for those who are unable to abstain.

Ethanol inhibits human osteoblastic cell proliferation

The habitual consumption of alcoholic beverages is clearly associated with low bone mass and an increased prevalence of skeletal fractures. Microscopic analysis of skeletal tissue from alcoholic patients reveals reduced osteoblast number and suppressed bone formation activity with a relative sparing of resorptive indices. The decreased number of osteoblasts observed in alcoholic subjects results from either impaired proliferation or accelerated senescence. Polyamines and ornithine decarboxylase (ODC), the rate-limiting enzyme for polyamine synthesis, are essential for cell proliferation in a variety of cell types. To determine if the adverse effect of ethanol on osteoblast number involves modulation of polyamine biosynthesis, we examined the effect of ethanol on parameters of cell growth and ODC activity in a human osteoblast-like osteosarcoma cell line (TE-85). Ethanol markedly impaired DNA synthesis and cell proliferation in a dose-dependent fashion, but alkaline phosphatase activity (a marker of differentiated osteoblast function) remained intact, and accelerated apoptosis was not evident. Thus, the reduced osteoblastic cell number was a result of a direct effect on proliferative processes rather than a nonspecific toxic effect of ethanol to accelerate cell death. Induction of ODC activity was impaired in ethanol-exposed cell cultures in a dose-dependent fashion that paralleled the antiproliferative effects. Finally, supplemental polyamine administration substantially improved DNA synthesis in ethanol-exposed UMR 106-01 cell cultures. These data confirm a direct inhibitory effect of ethanol on osteoblast proliferation without overt cellular toxicity that may, in part, explain the reduced bone mass observed in those who consume excessive amounts of alcohol.

The intrinsic antimicrobial activity of selected sclerosing agents in sclerotherapy

BACKGROUND

Detergent sclerosing agents may have intrinsic antimicrobial properties. In addition, they may have synergistic effects with other antibiotics such as penicillin. They may induce suppression of intrinsic resistance to penicillin in Staphylococcus aureus.

OBJECTIVE

It is in this setting that the present study was carried out in order to determine the degree of suppression of resistance to methicillin and oxacillin in S. aureus by two detergent sclerosing solutions.

METHODS

Four strains of S. aureus including a quality control strain were isolated. The minimal inhibitory concentration (MIC) of Sotradecol 1.0% and Polidocanol 0.5% were determined in Mueller Hinton Broth. These dilutions were subsequently seeded with 10(5) organisms of the strain of S. aureus being tested. Serial dilutions of penicillin were made and then the sclerosing agents were added in the appropriate dilutions.

RESULTS

Sotradecol 1.0% produced a MIC of 1/64 in two strains of S. aureus and 1/128 in two other variant strains. Polidocanol 0.5% produced a MIC of 1/64 against two strains of S. aureus and an MIC of 1/8 and 1/4 with two other variant strains. In addition, in three of the four S. aureus strains both sclerosing agents had synergistic activity with penicillin and augmented its activity approximately 16-fold.

CONCLUSION

This study presents the first successful modification in which detergent sclerosing solutions influence methicillin resistance in a Staphylococcal species. This points out a new potential therapeutic indication for this class of agents.

Inhibition of osteoblastic cell proliferation and ornithine decarboxylase activity by ethanol

Low bone mass and an increased prevalence of skeletal fractures are evident in the alcoholic population. Histomorphometric analysis of skeletal tissue from alcoholic patients reveals reduced osteoblast number and suppressed bone formation activity, with relative sparing of resorptive indexes. The decreased number of osteoblasts observed in alcoholic subjects results from either impaired proliferation or accelerated senescence. Polyamines and ornithine decarboxylase (ODC), the rate-limiting enzyme for polyamine synthesis, are essential for cell proliferation in a variety of cell types. To determine whether the consequences of ethanol on osteoblast number involve the modulation of polyamine biosynthesis, we examined the effect of ethanol on parameters of cell growth and ODC activity in a rat osteoblast-like osteosarcoma cell line (UMR 106-01). Ethanol markedly impaired DNA synthesis and cell proliferation in a dose-dependent fashion. Difluoromethylornithine, a specific inhibitor of ODC activity, induced a similar inhibition of UMR 106-01 cell proliferation, indicating the importance of the polyamine pathway in this osteoblastic cell line. Induction of ODC activity was impaired in ethanol-exposed cell cultures in a dose-dependent fashion that paralleled the antiproliferative effects. Finally, supplemental polyamine administration substantially improved DNA synthesis in ethanol-exposed UMR 106-01 cell cultures. These data confirm a direct inhibitory effect of ethanol on osteoblast proliferation that may in part explain the reduced bone mass observed in subjects who consume excessive amounts of alcohol. These findings also suggest that altered polyamine metabolism may be an important mechanism responsible for the antiproliferative effects of ethanol on the osteoblast.

Chiral resolution of cationic drugs of forensic interest by capillary electrophoresis with mixtures of neutral and anionic cyclodextrins

Chiral resolution of a number of cationic drugs of forensic interest (amphetamine, methamphetamine, cathinone, methcathinone, cathine, cocaine, propoxyphene, and various alpha-hydroxyphenethylamines) is achieved via capillary electrophoresis (CE) with added cyclodextrins (CDs), including novel mixtures of neutral and anionic CDs. In the latter studies, resolution and migration speed are readily adjusted by varying the ratio of the two added CDs, as the anionic CD acts as a counter-migrating complexing reagent. The neutral CD, heptakis(2,6-di-O-methyl)-beta-CD, was found suitable for the analysis of illicit cocaine and khat leaves (Catha edulis Forsk), which contain (-)-alpha-aminopropiophenone ((-)-cathinone), (+)-norpseudoephedrine (cathine), (-)-norephedrine, and trace levels of the phenylpentenylamines (+)-merucathinone, (+)-merucathine, and possibly (-)-pseudomerucathine. The use of mixtures of the neutral and the anionic CD (beta-CD sulfobutyl ether IV) was found suitable for the analysis of illicit amphetamine, methamphetamine, methcathinone, and propoxyphene. A model is presented for the impact of mixtures of neutral and anionic CDs on migration behavior and chiral resolution in CE.

Antineurofilament and antiretinal antibodies in AIDS patients with cytomegalovirus retinitis

Sera obtained from AIDS patients with cytomegalovirus (CMV) retinitis before and after treatment with foscarnet, AIDS patients with human immunodeficiency virus (HIV) retinopathy, AIDS patients without retinal disease, and normal healthy controls with and without positive CMV serologies were assayed for the presence of antibodies against the 200-kDa outer, 160-kDa middle, and 68-kDa core subunits of the neurofilament triplet. Additional studies were performed to determine the presence of antibodies reactive with proteins extracted from crude human retinal antigen preparations. Antibodies against the 200-, 260-, and 68-kDa proteins of the neurofilament triplet were detected in 15 of 15 AIDS patients with CMV retinitis. The expression of these antibodies was unaffected, qualitatively, by successful treatment with foscarnet. In contrast, only 30% of patients with HIV retinopathy unrelated to CMV, fewer than 35% of AIDS patients with positive CMV titers but without evident retinitis, and fewer than 25% of healthy controls with positive or negative CMV titers possessed antibodies against any of the triplet proteins (P < 0.001). Antibodies against several clusters of retinal antigens were also identified in the sera of patients with CMV retinitis. In summary, the data indicate that retinal elements damaged by CMV infection induce an antibody response against the 200-, 160-, and 68kDa components of the neurofilament triplet as well as other, as yet undefined retinal antigens.

Determination and in-depth chromatographic analyses of alkaloids in South American and greenhouse-cultivated coca leaves

Methodology is described for the detection and/or determination of cocaine and minor alkaloids in South American coca as well as in greenhouse- and tropical-cultivated field coca of known taxonomy. Coca leaf from Bolivia, Peru, Ecuador and Colombia were subjected to the determination of cocaine, cis- and trans-cinnamoylcocaine, tropacocaine, hygrine, cuscohygrine and the isomeric truxillines. The greenhouse samples were cocaine-bearing leaves of the genus Erythroxylum and included E. coca var. coca, E. novogranatense var. novogranatense and E. novogranatense var. truxillense, and the alkaloids determined were cocaine, ecgonine methyl ester, cuscohygrine, tropacocaine and the cinnamoylcocaines. The tropical-cultivated coca were E. novogranatense var. novogranatense and E. coca var. coca. Cocaine and minor alkaloids were isolated from basified powdered leaf samples using a toluene extractant, followed by acid-Celite column chromatography. The isolated alkaloids were determined by capillary gas chromatography with flame ionization or electron-capture detection. Methodology is also presented for the isolation and mass spectral analysis of numerous trace-level coca alkaloids of unknown structure.

Illicit Production of Cocaine

The predominant methods currently used for illicit production of cocaine are described. For illicit natural cocaine (i.e., from coca leaf), this includes production of coca paste from coca leaf via both the solvent and acid extraction techniques, purification of coca paste to cocaine base, and conversion of cocaine base to cocaine hydrochloride. For illicit synthetic cocaine (i.e., synthesized from precursor chemicals), the classic five-step synthetic route used in all clandestine laboratories seized to date is summarized. The origins of the most common alkaloidal impurities and processing/synthetic by-products typically identified in illicit natural, illicit synthetic, and pharmaceutical cocaine are discussed. Forensic differentiation of exhibits arising from the various production methods are addressed both in terms of overall product purity and the presence/absence of these impurities and by-products.

Regulation of osteoblastic gene expression by lead

Although it is well recognized that lead accumulates in bone, skeletal tissue is considered primarily a sequestering compartment and not a site of toxic action for lead. However, exposure to lead is associated with impaired skeletal growth in children and reductions in indices of bone formation in laboratory animals. Osteoblastic ROS 17/2.8 cells were used in an effort to better understand the consequences of lead exposure on skeletal homeostasis. Studies on confluent cultures of ROS 17/2.8 cells revealed that lead (2-200 microM) had no effect on cell number or DNA and protein synthesis. However, alkaline phosphatase activity was reduced by lead in a dose- and time-dependent manner. Reductions in steady state alkaline phosphatase mRNA levels paralleled the lead-induced inhibition of enzyme activity. Moreover, lead exposure resulted in similar dose-dependent reductions in steady state type 1 procollagen and bone Gla protein mRNA levels. The effect of lead on osteoblastic gene expression in ROS 17/2.8 cultures, however, was selective in nature, as similar lead exposures resulted in no alterations in beta-actin or glyceraldehyde-3-phosphate dehydrogenase mRNA levels. These data demonstrate that lead, in the absence of over toxicity, specifically restricts the expression of certain aspects of the differentiated osteoblast phenotype. Such alterations in osteoblast function may contribute to the skeletal abnormalities observed in settings of lead intoxication.

Pertussis toxin inhibits hormonal stimulation of bone resorption in fetal rat limb bones

The cellular basis for hormonal control of bone resorption is poorly understood. As the identifiable receptors for bone resorbing agents such as parathyroid hormone (PTH) and 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] are located on osteoblasts rather than osteoclasts, the nature of cellular signaling is obscure. Here it is reported that exposure of fetal rat limb bones to pertussis toxin, a bacterial protein that inhibits certain GTP binding proteins (G-proteins) involved in signal transduction, markedly inhibits bone resorption elicited by PTH, 1,25(OH)2D3 and prostaglandin E2. Pertussis toxin does not block the inhibition of alkaline phosphatase activity by PTH or 1,25(OH)2D3, and it potentiates the cyclic AMP response to PTH. These data support the existence of a pertussis toxin-sensitive G-protein that participates in regulation of bone resorption. The putative G-protein is apparently not involved in the initial transduction of hormonal signals, but it may be part of a final common pathway through which the osteoclast is activated by agents with widely divergent initial actions.

Increased serum levels of a parathyroid hormone-like protein in malignancy-associated hypercalcemia

STUDY OBJECTIVE

To measure the serum levels of a newly described parathyroid hormone-like protein (PLP) which was isolated from malignant tumors associated with hypercalcemia, and determine whether PLP is a humoral factor in malignancy-associated hypercalcemia.

DESIGN

A cross-sectional study of serum levels of PLP using a newly developed radioimmunoassay.

SETTING

A university-affiliated Veterans Administration hospital in San Francisco, California, a University hospital in Hong Kong, and a private hospital in Danville, Pennsylvania.

PATIENTS

Patients with hypercalcemia (calcium greater than 2.65 mmol/L) and a diagnosis of malignancy were studied. Control groups included normocalcemic patients with malignancy, patients with hyperparathyroidism, and normal subjects.

MEASUREMENTS AND MAIN RESULTS

Serum immunoreactive PLP (iPLP) levels in normal subjects were less than 2.5 pmol eq/L (10 pg/mL), and 68% of subjects had undetectable levels. The serum concentration of iPLP was normal in 15 of 16 hypercalcemic patients with hyperparathyroidism. Serum iPLP was increased (greater than 2.5 pmol eq/L) in 36 of 65 (55%) patients with malignancy-associated hypercalcemia, with a mean value of 6.1 +/- 0.9 pmol eq/L (24 pg/mL). In a subgroup of patients with solid tumors serum iPLP was increased in 30 (71%) of 42 hypercalcemic patients, with a mean value of 6.5 +/- 0.9 pmol eq/L. Serum iPLP was elevated in only 3 of 23 normocalcemic patients with cancer. In patients with solid malignancies (n = 59), levels of iPLP were positively correlated with the total serum calcium (r = 0.43, P less than 0.01).

CONCLUSION

The data indicate a relation between the serum concentration of iPLP and the presence of hypercalcemia in solid malignancies. The results support a role for PLP as a humoral mediator of hypercalcemia in most patients with solid tumors. Measurement of iPLP should be useful in the differential diagnosis of hypercalcemia.

The effect of interleukin-1 alpha and tumor necrosis factor alpha on the secretion of human chorionic gonadotropin by JAR human choriocarcinoma cells

The regulation of human chorionic gonadotropin (hCG) secretion by placental trophoblasts is incompletely understood. A recent study reports that Interleukin-1 beta (IL-1 beta) stimulates hCG production in vitro by human, first trimester, placental trophoblasts, but not by a human choriocarcinoma cell line. Human decidua has been shown to produce IL-1 alpha and beta, and Tumor Necrosis Factor alpha (TNF alpha). The precise role(s) of these proteins in pregnancy is unknown. In the present study, hCG production by human choriocarcinoma cells (JAR) was evaluated in the presence of recombinant human IL-1 alpha (rHIL-1 alpha) and rHTNF alpha. hCG production was increased by rHIL-1 alpha in a dose-dependent manner, and heat-inactivation of this cytokine abolished the effect. Equimolar quantities of rHTNF alpha failed to influence hCG production or cell viability. IL-1 may be important in the regulation of hCG production by human trophoblasts, and therefore may play a physiologic role in pregnancy. Furthermore, TNF does not appear to participate in the regulation of the production of this hormone by human choriocarcinoma cells. This is the first demonstration of a divergence of activity of these two cytokines in the reproductive process.

Forskolin mimics the effects of calcitonin but not parathyroid hormone on bone resorption in vitro

Parathyroid hormone (PTH) and calcitonin stimulate bone adenylate cyclase activity and increase bone cAMP content, but PTH enhances and calcitonin inhibits bone resorption. This study examined the effects of forskolin, a non-hormonal activator of adenylate cyclase, on bone resorption and cAMP accumulation in 19-day fetal rat limb bones. Forskolin (10(-9) to 10(-5) M) stimulated bone cAMP generation in a concentration-dependent manner. However, in contrast to bPTH(1-34), which also stimulated cAMP accumulation, forskolin did not stimulate bone resorption. Moreover, forskolin did not augment the bone-resorbing activity of PTH even though it potentiated PTH stimulation of bone cAMP levels. Rather, high doses of forskolin (10(-6) to 10(-5) M) exhibited a calcitonin-like effect to inhibit PTH-mediated bone resorption. These results support a second-messenger function of cAMP for the inhibitory effects of calcitonin, but not for the stimulatory effects of PTH on bone resorption.

Effects of tobacco glycoprotein (TGP) on the immune system. II. TGP stimulates the proliferation of human T cells and the differentiation of human B cells into Ig secreting cells

We have been studying the effects of tobacco glycoprotein (TGP), a polyphenol-rich glycoprotein isolated from cured tobacco leaves, on the immune system. We have shown previously that mice immunized with TGP produce preferentially antibodies of the IgE isotype and that TGP is a T cell-independent B cell mitogen for mice, which stimulates B cell proliferation and B cell differentiation into Ig-secreting cells. We report herein that TGP stimulates a significant increase in [3H]TdR incorporation by human PBL and by human cord blood lymphocytes. The magnitude of the proliferative response of PBL to TGP does not correlate with the donor's titer of IgE antibodies to TGP, as assayed by a wheal and flare response after an i.d. injection of TGP, neither does it correlate with the donor's smoking history. [3H]TdR uptake is not observed before day 5 of culture, and the response peaks between days 5 and 10 of culture. Analysis of the cellular basis for the proliferative response suggests that T cells are proliferating. Two-parameter analysis by flow cytometry shows that CD3+, CD4+, and CD8+ cells are in the S + G2 + M phases, but not Ig-bearing cells or monocytes. A significant increase in HLA-DR (Ia)-bearing cells is observed on cells in all of the cell cycle phases. This increase coincides with cells entering the S phase. No increase is observed in the expression of the IL-2-R as assayed by the anti-Tac antibody. TGP also stimulates human PBL to differentiate and to produce Ig of the IgM, IgG, and IgA isotypes, without stimulating a detectable B cell proliferative response. The proliferative response of PBL is clearly due to TGP and not to contamination with LPS, because by the limulus amebocyte assay the TGP preparation contains less than 2% LPS, which could not account for the stimulation observed.

Effects of tobacco glycoprotein (TGP) on the immune system. II. TGP stimulates the proliferation of human T cells and the differentiation of human B cells into Ig secreting cells

We have been studying the effects of tobacco glycoprotein (TGP), a polyphenol-rich glycoprotein isolated from cured tobacco leaves, on the immune system. We have shown previously that mice immunized with TGP produce preferentially antibodies of the IgE isotype and that TGP is a T cell-independent B cell mitogen for mice, which stimulates B cell proliferation and B cell differentiation into Ig-secreting cells. We report herein that TGP stimulates a significant increase in [3H]TdR incorporation by human PBL and by human cord blood lymphocytes. The magnitude of the proliferative response of PBL to TGP does not correlate with the donor's titer of IgE antibodies to TGP, as assayed by a wheal and flare response after an i.d. injection of TGP, neither does it correlate with the donor's smoking history. [3H]TdR uptake is not observed before day 5 of culture, and the response peaks between days 5 and 10 of culture. Analysis of the cellular basis for the proliferative response suggests that T cells are proliferating. Two-parameter analysis by flow cytometry shows that CD3+, CD4+, and CD8+ cells are in the S + G2 + M phases, but not Ig-bearing cells or monocytes. A significant increase in HLA-DR (Ia)-bearing cells is observed on cells in all of the cell cycle phases. This increase coincides with cells entering the S phase. No increase is observed in the expression of the IL-2-R as assayed by the anti-Tac antibody. TGP also stimulates human PBL to differentiate and to produce Ig of the IgM, IgG, and IgA isotypes, without stimulating a detectable B cell proliferative response. The proliferative response of PBL is clearly due to TGP and not to contamination with LPS, because by the limulus amebocyte assay the TGP preparation contains less than 2% LPS, which could not account for the stimulation observed.

Parathyroid hormonelike protein from human renal carcinoma cells. Structural and functional homology with parathyroid hormone

A variety of solid tumors secrete proteins that are immunochemically distinct from parathyroid hormone (PTH) but activate PTH-responsive adenylate cyclase. Such PTH-like proteins have been proposed as mediators of the hypercalcemia and hypophosphatemia frequently associated with malignancies. We purified to apparent homogeneity a PTH-like protein with a molecular weight of 6,000, that is produced by human renal carcinoma cells. The amino-terminal sequence of the PTH-like protein and that of human PTH were found to display at least five identities in the first 13 positions. The purified protein bound to PTH receptors, activated adenylate cyclase in renal plasma membranes, and stimulated cAMP formation in rat osteosarcoma cells. The PTH-like protein reproduced two additional effects of PTH, stimulation of bone resorption in fetal rat limb bone cultures and inhibition of phosphate uptake in cultured opossum kidney cells. These properties are consistent with a role for PTH-like proteins as mediators of the syndrome of malignancy-associated hypercalcemia.

Effect of age on circulating immunoreactive and bioactive parathyroid hormone levels in women

Although levels of serum immunoreactive parathyroid hormone (iPTH) increase with age in women, this could be caused by retention of non-biologically active PTH fragments by the aging kidney. In 102 normal women, aged 30 to 89 yr, serum iPTH increased with age by 58% (r = 0.33, p less than 0.001) with antiserum GP-1M (which has midmolecule specificity) and 43% (r = 0.32, p less than 0.001) with antiserum CH-12M (which may have whole molecule specificity); urinary cAMP/GFR excretion increased by 29% (r = 0.22, p less than 0.05). The results of these assays were validated by comparison with serum levels of biologically active PTH (BioPTH) in immunoextracts of serum followed by renal adenylate cyclase assay in a selected subgroup of 25 of the women. Serum BioPTH correlated with serum iPTH assessed by antiserum GP-1M (r = 0.48, p less than 0.05) and antiserum CH-12M (r = 0.48, p less than 0.05) but not with urinary cAMP. The data are consistent with an increase of parathyroid function with aging: clearly, we do not find decreased parathyroid function as would be expected if age-related bone loss was not mediated, in part, by PTH.

Relationship of muscle capillary basement membrane thickness and diabetic retinopathy

We examined the relationship between the thickness of the quadriceps muscle capillary basement membrane and diabetic retinopathy. Basement membrane thickness was measured in two groups of patients with long-standing type II diabetes mellitus. One group of patients (N = 13) had no evidence of diabetic retinopathy on fluorescein angiography, whereas the other (N = 12) had proliferative microvascular disease. All the patients were male, and both groups were of similar ages, duration of diabetes, serum creatinines, and glycemic control as reflected by HbA1 levels. Mean muscle capillary basement membrane width (+/- SE) of the patients with proliferative retinopathy (3346 +/- 262) was significantly greater (P less than .05) than that observed in the patients without retinopathy (2660 +/- 177). The results of this study suggest that there is a relationship between capillary basement membrane thickness in skeletal muscle and the severity of microangiopathy in the eye. However, there was a substantial overlap between the two groups, indicating that for any individual patient the measurement of muscle capillary basement width will probably not be useful in identifying the presence or absence of retinopathy.

Parathyroid hormone-like adenylate cyclase-stimulating activity from a human carcinoma is associated with bone-resorbing activity

We found previously that a human renal carcinoma cell line derived from a hypercalcemic patient induces humoral hypercalcemia when grown as allografts in the nude mouse and secretes a protein that activates adenylate cyclase via the PTH receptor. The purpose of this study was to examine the conditioned medium of this cell line for bone-resorbing activity in vitro. Processed conditioned medium produced dose-dependent stimulation of bone resorption in cultured fetal rat limb bone explants. Two PTH antagonists were used to assess the PTH receptor dependence of this bone-resorbing activity. Neither [8Nle,18Nle,34Tyr]bovine (b) PTH-(3-34) amide nor [34Tyr]bPTH-(7-34)amide inhibited bone resorption or limb bone cAMP accumulation induced by either processed conditioned medium or equivalent concentrations of bPTH-(1-34). As an alternate means to assess whether this tumor-derived PTH-like protein had intrinsic bone-resorbing activity, the latter was measured during partial purification of PTH-like adenylate cyclase-stimulating activity (ACSA) from conditioned medium by consecutive gel filtration and reverse phase HPLC. The bone-resorbing activity in conditioned medium could not be resolved from PTH-like ACSA by these two separation techniques, indicating that the activities may be intrinsic to the same protein. These results are consistent with the view that a tumor-derived protein with PTH-like ACSA and bone-resorbing activity may be responsible for hypercalcemia in vivo.

Immune complex glomerulopathy in a child with food hypersensitivity

This report describes the occurrence of immune complex glomerulonephritis in a patient with eosinophilic gastroenteritis and food hypersensitivity. A coincident allergen injection may have been a contributing factor in the sudden development of the nephrotic syndrome. Markedly elevated levels of circulating immune complexes (greater than 6400 mg/dl) were found containing kappa-casein and bovine serum albumin (BSA), the latter predominating. Markedly elevated serum BSA hemagglutinating titers were also present (1:40,960). Cross-reacting precipitating antibodies to BSA, beef, and pork were demonstrated, but not to flounder or ovalbumin. Renal biopsy revealed immune complex glomerulonephritis with BSA, immunoglobulins M and G and complement deposited focally in the glomerular basement membrane. With strict dietary limitation of identified causative antigens and prednisone therapy, CIC levels decreased to 16,000 micrograms/dl and serum BSA antibody hemagglutinating titer fell 32-fold over a period of 15 months. There was prompt symptomatic relief and amelioration of signs of nephritis. The patient was able to consume a diet normal in protein and caloric content, and statural catch-up growth occurred. Recognition of food antigens to which the patient was hypersensitive provided a rationale for the relief of the gastrointestinal disturbance, growth stunting, and renal disease.

Reimplantation in infection. Elution of gentamicin from cement and beads

A prospective study was performed to evaluate the arthroplasty fluid, serum, and urine antibiotic levels in 38 patients implanted with gentamicin-impregnated cement and in 18 patients with gentamicin-impregnated beads. Radioimmune assays were performed on arthroplasty fluid, serum, and urine samples at various times after surgery. On day 1, high arthroplasty fluid levels of gentamicin were eluted from bead-implanted patients (mean, 36.9 micrograms/ml; range, 19.6-69.5) and cement-implanted patients (mean, 14.9 micrograms/ml; range, 2.7-38.9) with very low serum and urine levels. The arthroplasty levels of gentamicin obtained in bead-implanted patients on day 1 were 17 times higher, and in cement-implanted patients, seven times higher, than those obtained with intravenous administration of gentamicin. The serum and urine levels were approximately ten to 20 times less in patients with gentamicin-impregnated cement or beads compared to those levels obtained after intravenous administration. These very low systemic levels should preclude nephrotoxic and ototoxic effects. No toxic effects were observed in these patients. Bioactivity of gentamicin in the specimens was confirmed. Staphylococci were exquisitely sensitive, while Streptococci were moderately resistant to gentamicin. Both gentamicin-impregnated beads and cement appear safe and provide substantial local in vivo antibacterial activity.

A trial of amitriptyline and fluphenazine in the treatment of painful diabetic neuropathy

We conducted a double-blind, placebo-controlled, crossover study of the effectiveness of amitriptyline and fluphenazine in alleviating the pain of diabetic peripheral neuropathy in six diabetic patients. Pain was evaluated by the patients with a graphic rating scale. A placebo response was found, but no additional effect of amitriptyline and fluphenazine was seen. Although the statistical power of this study was low, these data, when combined with a reevaluation of previous trials of amitriptyline and fluphenazine in the treatment of painful diabetic neuropathy, indicate that there is no justification for the use of these agents in the treatment of painful neuropathy outside of large, controlled clinical trials. Depression as a possible cause of this condition should not go unnoted or untreated.