'Sink or swim': an evaluation of the clinical characteristics of individuals with high bone mass

SUMMARY

High bone mineral density on routine dual energy X-ray absorptiometry (DXA) may indicate an underlying skeletal dysplasia. Two hundred fifty-eight individuals with unexplained high bone mass (HBM), 236 relatives (41% with HBM) and 58 spouses were studied. Cases could not float, had mandible enlargement, extra bone, broad frames, larger shoe sizes and increased body mass index (BMI). HBM cases may harbour an underlying genetic disorder.

INTRODUCTION

High bone mineral density is a sporadic incidental finding on routine DXA scanning of apparently asymptomatic individuals. Such individuals may have an underlying skeletal dysplasia, as seen in LRP5 mutations. We aimed to characterize unexplained HBM and determine the potential for an underlying skeletal dysplasia.

METHODS

Two hundred fifty-eight individuals with unexplained HBM (defined as L1 Z-score ≥ +3.2 plus total hip Z-score ≥ +1.2, or total hip Z-score ≥ +3.2) were recruited from 15 UK centres, by screening 335,115 DXA scans. Unexplained HBM affected 0.181% of DXA scans. Next 236 relatives were recruited of whom 94 (41%) had HBM (defined as L1 Z-score + total hip Z-score ≥ +3.2). Fifty-eight spouses were also recruited together with the unaffected relatives as controls. Phenotypes of cases and controls, obtained from clinical assessment, were compared using random-effects linear and logistic regression models, clustered by family, adjusted for confounders, including age and sex.

RESULTS

Individuals with unexplained HBM had an excess of sinking when swimming (7.11 [3.65, 13.84], p < 0.001; adjusted odds ratio with 95% confidence interval shown), mandible enlargement (4.16 [2.34, 7.39], p < 0.001), extra bone at tendon/ligament insertions (2.07 [1.13, 3.78], p = 0.018) and broad frame (3.55 [2.12, 5.95], p < 0.001). HBM cases also had a larger shoe size (mean difference 0.4 [0.1, 0.7] UK sizes, p = 0.009) and increased BMI (mean difference 2.2 [1.3, 3.1] kg/m(2), p < 0.001).

CONCLUSION

Individuals with unexplained HBM have an excess of clinical characteristics associated with skeletal dysplasia and their relatives are commonly affected, suggesting many may harbour an underlying genetic disorder affecting bone mass.

Mutations in holoprosencephaly

Holoprosencephaly (HPE) is the most common developmental defect of the forebrain and midface in humans. In holoprosencephaly the cerebral hemispheres of the brain fail to separate into distinct left and right hemispheres. This malformation is due to the improper specification and formation of the forebrain during early development. When one considers the great number and kinds of genetic interactions that must occur to properly pattern the developing forebrain, it is not surprising that HPE is extremely heterogeneous. In addition to teratogenic agents, several genes are implicated as the cause of HPE. At least 12 different loci have been associated with HPE and now several distinct human genes for holoprosencephaly have been identified. These genes include Sonic Hedgehog (SHH), ZIC2, SIX3, and TG-interacting factor (TGIF). Here we present an overview of the presently known genes causing human holoprosencephaly. We discuss their functional role in development of the forebrain and summarize the mutations and polymorphisms that have been identified within them. Hum Mutat 16:99-108, 2000. Published 2000 Wiley-Liss, Inc.

Isolation and preliminary characterization of the human and mouse homologues of the bacterial cell cycle gene era

Era is an essential GTPase that is required for proper cell cycle progression and cell division in Escherichia coli and is found in nearly all bacteria sequenced to date. To determine whether Era is also present in eukaryotic organisms, we searched the dbEST database and found EST clones coding for proteins that were similar to Era. Full sequencing of these ESTs from human and mouse identified a conserved homologue, ERAL1 (Era-like 1). ERAL1 maps to 17q11.2 in human and is located in the syntenic region of mouse chromosome 11. ERAL1 may be an attractive candidate for a tumor suppressor gene since ERAL1 is located in a chromosomal region where loss of heterozygosity is often associated with various types of cancer.

ARP3beta, the gene encoding a new human actin-related protein, is alternatively spliced and predominantly expressed in brain neuronal cells

A cDNA encoding a new human actin-related protein (ARP) was cloned. The corresponding protein is highly conserved with the previously described ARP3 protein, suggesting that it represents a second isoform of the human ARP3 subfamily. This new actin-related protein was subsequently named ARP3beta and represents the second example of multiple isoforms of an actin-related protein in a single organism. The ARP3beta gene was mapped to chromosome band 7q34, centromeric to Sonic Hedgehog. Gene structure analysis revealed that at least part of the observed ARP3beta mRNA heterogeneity is caused by alternative splicing resulting in exon skipping. Transcripts produced after exon 2 skipping are predicted to encode truncated products, whose functionality is still unclear. An ARP3beta pseudogene was detected on chromosome 2p11 by database searching. Several ARP3beta mRNA species were detected by Northern blotting and their abundance varied importantly among tissues: the highest expression levels were detected in fetal and adult brain, whereas lower levels were observed in liver, muscle and pancreas. In contrast, ARP3 mRNAs were detected in all tissues tested. Using in situ hybridization, the expression of ARP3beta in brain was shown to be restricted to neurons and epithelial cells from choroid plexus. This suggests a specific function for ARP3beta in the physiology of the development and/or maintenance of distinct subsets of nerve cells.

Glove usage and reporting of needlestick injuries by junior hospital medical staff

The use of gloves when conducting invasive procedures and the reporting of needlestick injuries have been strongly encouraged. Despite this, neither practice appears to be universal. In order to determine the rates of glove usage and needlestick injury reporting, we conducted a survey of junior doctors in three hospitals in the UK. Of the 190 respondents, the majority rarely wore gloves for venesection, insertion of intravenous cannulas or arterial blood gas sampling. For more major procedures (insertion of central venous lines, insertion of thoracostomy tubes, suturing) gloves were invariably worn. Only 17.5% of needlestick injuries were reported. The rates of glove usage and needlestick injury reporting were lower than previous studies have demonstrated in North America. Surgeons suffered the most needlestick injuries and were the least likely to report them. The low reporting rate may have serious implications, particularly in view of the new Government guidelines on needlestick injuries which involve HIV-infected blood. By failing to use gloves and report needlestick injuries, junior doctors, in particular surgeons, are placing themselves and patients at increased risk of blood-borne transmissible diseases.

Cardiac neurones of autonomic ganglia

The properties of the postganglionic sympathetic neurones supplying the heart and arising in the stellate and adjacent paravertebral ganglia of various species are discussed with respect to their location, morphology, synaptic input and membrane characteristics. Results from our laboratory on the morphology of rat stellate neurones projecting to the heart were obtained either by intracellular injection of hexammine cobaltic (III) chloride or by retrograde labelling of cells using cobalt-lysine complex. Intracellular recordings were made from cells using electrodes filled either with potassium chloride plus hexammine cobaltic chloride or potassium acetate. Neurones which projected axons into cardiac nerve branches arising from the stellate ganglion were termed putative cardiac neurones, because of the possibility that some supply pulmonary targets. Putative cardiac neurones had unbranched axons and were ovoid or polygonal in shape, but showed considerable variation in soma size and in the complexity of dendritic trees. The mean two-dimensional surface area was 463 microns2 and the mean number of primary dendrites was seven. Other studies have found that the morphology of rat stellate ganglion neurones is similar to that of superior cervical ganglion cells. However, in strains of rat displaying spontaneous hypertension, dendritic length may be increased. Histochemical studies do not, as yet, seem to have demonstrated a distinctive neurochemical profile for stellate cardiac neurones, but various types of peptide-containing intraganglionic nerve fibres have been identified in the guinea pig. In our electrophysiological studies, putative cardiac neurones were found to receive a complex presynaptic input arising from the caudal sympathetic trunk and from T1 and T2 thoracic rami. In addition, 16% of cardiac neurones received a synaptic input from the cardiac nerve. The properties of postganglionic parasympathetic neurones distributed in the cardiac plexus and termed intrinsic cardiac neurones are discussed, including the results of studies on cultures of these neurones.

Cardiac neurones of autonomic ganglia

The properties of the postganglionic sympathetic neurones supplying the heart and arising in the stellate and adjacent paravertebral ganglia of various species are discussed with respect to their location, morphology, synaptic input and membrane characteristics. Results from our laboratory on the morphology of rat stellate neurones projecting to the heart were obtained either by intracellular injection of hexammine cobaltic (III) chloride or by retrograde labelling of cells using cobalt-lysine complex. Intracellular recordings were made from cells using electrodes filled either with potassium chloride plus hexammine cobaltic chloride or potassium acetate. Neurones which projected axons into cardiac nerve branches arising from the stellate ganglion were termed putative cardiac neurones, because of the possibility that some supply pulmonary targets. Putative cardiac neurones had unbranched axons and were ovoid or polygonal in shape, but showed considerable variation in soma size and in the complexity of dendritic trees. The mean two-dimensional surface area was 463 microns2 and the mean number of primary dendrites was seven. Other studies have found that the morphology of rat stellate ganglion neurones is similar to that of superior cervical ganglion cells. However, in strains of rat displaying spontaneous hypertension, dendritic length may be increased. Histochemical studies do not, as yet, seem to have demonstrated a distinctive neurochemical profile for stellate cardiac neurones, but various types of peptide-containing intraganglionic nerve fibres have been identified in the guinea pig. In our electrophysiological studies, putative cardiac neurones were found to receive a complex presynaptic input arising from the caudal sympathetic trunk and from T1 and T2 thoracic rami. In addition, 16% of cardiac neurones received a synaptic input from the cardiac nerve. The properties of postganglionic parasympathetic neurones distributed in the cardiac plexus and termed intrinsic cardiac neurones are discussed, including the results of studies on cultures of these neurones.

Successful treatment of heparin-associated thrombocytopenia and thrombosis using Hirulog

Heparin-associated thrombocytopenia is a serious medical problem, especially when the patient requires continued anticoagulation. Hirulog is an immediate-acting intravenous anticoagulant that can be substituted for heparin. A new use of Hirulog in the treatment of life-threatening heparin-associated thrombocytopenia with thrombosis (HATT) is presented. Two patients suffering from the HATT syndrome were successfully treated with Hirulog to prevent further thrombosis. A third patient had developed heparin-associated thrombocytopenia after coronary artery bypass surgery in the past and was subsequently treated with Hirulog during a peripheral angioplasty procedure. Hirulog was an effective and predictable anticoagulant for these patients and was free from adverse effects.

Mapping the bovine homolog of the human cystic fibrosis gene

Human cDNA probe H1.6 (clone 10-1) encoding cystic fibrosis transmembrane conductance regulator (CFTR) was used to map the bovine homolog of CFTR. Using a panel of bovine x rodent hybrid somatic cells, the homolog was mapped to bovine syntenic group U13 which corresponds to chromosome 4. CFTR is 97.7% concordant with syntenic markers T-cell receptor beta (TCRB) and P-glycoprotein 3 (PGY3). The comparative gene maps of CFTR, TCRB, and PGY3 on human chromosome 7, bovine chromosome 4, and mouse chromosome 5 and 6 indicate conservation of synteny, although internal rearrangements relative to HSA 7 are present in both cattle and mice.

Failure of ancrod in the treatment of heparin-induced arterial thrombosis

The morbidity and mortality associated with heparin-induced thrombosis remain high despite numerous empirical therapies. Ancrod has been used successfully for prophylaxis against development of thrombosis in patients with heparin induced platelet aggregation who require brief reexposure to heparin, but its success in patients who have developed the thrombosis syndrome is not well defined. The authors present a case of failure of ancrod treatment in a patient with heparin-induced thrombosis.

Epidemiology and financial impact of fowl cholera in turkeys: a retrospective analysis

A retrospective study of the epidemiology and financial impact of fowl cholera (FC) in California meat turkeys during 1984 was performed. Data were collected from 64 flocks--23 FC-outbreak flocks and 41 controls (non-outbreak)--raised in the Central Valley of the state. Mean flock age at the time of the FC outbreak was 11.3 weeks. Flocks that reported a colibacillosis outbreak had increased odds (P = 0.11) of also having an FC outbreak. (This association may or may not indicate a cause-effect relationship.) There was no significant difference between FC-outbreak and control flocks in number of diseases reported, age at onset, or duration of diseases or syndromes except age at onset of roundheart disease. The relative mortality rates were 52% higher in FC-outbreak toms and 26% higher in FC-outbreak hens than in their controls. Medication costs were nearly tripled, and the relative condemnation rate was 60% higher in FC-outbreak flocks than in control flocks. The average costs of FC were nearly $0.40 per bird, or $18,750 per flock, in an outbreak flock of 50,000 birds, and $0.12 per bird, or $6000 per flock, in non-outbreak flocks vaccinated against FC.

Transient bundle branch block following use of hypothermic cardioplegia in coronary artery bypass surgery: high incidence without perioperative myocardial infarction

Hypothermic cardioplegia (HCP) is a method commonly used for myocardial preservation at the time of aortic cross-clamping during coronary artery bypass grafting (CABG). This study assessed the frequency and significance of transient bundle branch block (BBB) in 50 patients undergoing CABG using HCP compared to 61 controls. All patients had normal QRS complexes on preoperative ECG. CLinical, hemodynamic, and operative data were similar in both groups. Seventeen (34%) of the HCP group and four (6%) of the controls developed postoperative BBB (p less than 0.001). These changes were transient in all but three patients in the HCP group. None of the HCP patients with transient BBB had evidence of perioperative myocardial infarction. Clinical and operative parameters did not provide prediction of development of transient BBB. This study demonstrates that transient BBB in the immediate post-CABG period occurs commonly with the use of HCP and does not indicate myocardial necrosis.

Relative activities of substances related to 5-hydroxytryptamine as depolarizing agents of superior cervical ganglion cells

Membrane potential changes evoked by 5-Ht and related substances were recorded by the sucrose-gap method from rabbit ganglia superfused with Krebs solution at 20 degrees C. A solution of the substance under test was injected into the superfusion stream. The activity of 23 substances was compared to that of 5-HT in respect of depolarizing capacity. 0.01 mumol 5-HT produced a near-threshold depolarization, while 0.6-0.8 mumol induced a maximal one. Some 5-HT analogues evoked prolonged responses distinctly different from the rapid depolarization and repolarization characteristic of 6-HT, while others were inactive. Compounds di- or trimethylated at the side-chain nitrogen atom were capable in addition of activating nicotinic receptors. The results suggest that: (1) the optimal requirements for activating ganglionic 5-HT receptors are a hydroxyl group at position 5 on the indole nucleus and a side-chain bearing an ethylamine amino group; (2) methyl substituents around the terminal nitrogen atom are well tolerated and a quaternary nitrogen may increase activity at the 5-HT receptor; and (3) substitution of a methyl group at carbon atom 2 of the indole nucleus reduces activity. A limitation of the technique is the difficulty of obtaining more than one dose-response curve from a particular preparation; a reduction in potency due to lower affinity cannot be readily distinguished from one due to lower intrinsic activity.