LDL receptor-related protein 5 (LRP5) affects bone accrual and eye development

In humans, low peak bone mass is a significant risk factor for osteoporosis. We report that LRP5, encoding the low-density lipoprotein receptor-related protein 5, affects bone mass accrual during growth. Mutations in LRP5 cause the autosomal recessive disorder osteoporosis-pseudoglioma syndrome (OPPG). We find that OPPG carriers have reduced bone mass when compared to age- and gender-matched controls. We demonstrate LRP5 expression by osteoblasts in situ and show that LRP5 can transduce Wnt signaling in vitro via the canonical pathway. We further show that a mutant-secreted form of LRP5 can reduce bone thickness in mouse calvarial explant cultures. These data indicate that Wnt-mediated signaling via LRP5 affects bone accrual during growth and is important for the establishment of peak bone mass.

Abnormal regulation of high affinity nicotinic receptors in subjects with schizophrenia

Previous studies have suggested that an abnormality in neuronal nicotinic acetylcholine receptor expression or function may be involved in the neuropathophysiology of schizophrenia. [(3)H]-nicotine and [(3)H]-epibatidine binding were compared in postmortem brain from control and schizophrenic subjects with varying smoking histories. In control subjects, increased receptor binding was seen in hippocampus, cortex, and caudate with increasing tobacco use. In contrast, schizophrenic smokers had reduced nicotinic receptor levels in these brain regions compared to control smokers. Chronic haloperidol and nicotine treatment, in the rat, was used to assess neuroleptic effects on receptor up-regulation by nicotine. A significant increase in cortical nicotinic receptors was seen in both nicotine treated as well as haloperidol and nicotine co-treated animals, suggesting that the abnormal regulation of high affinity neuronal nicotinic receptors in schizophrenics following nicotine use was not related to chronic neuroleptic treatment.

Comparison of the regional expression of nicotinic acetylcholine receptor alpha7 mRNA and [125I]-alpha-bungarotoxin binding in human postmortem brain

Neuronal nicotinic acetylcholine receptors are expressed in the human central nervous system. A specific subtype of this receptor family, the alpha7 nicotinic acetylcholine receptor, is thought to be the principal alpha-bungarotoxin (alphaBTX)-binding protein in mammalian brain. Although the expression of this receptor subtype has been characterized in rat, no study has specifically compared the expression of both the alpha7 gene and the localization of BTX binding sites in human brain. Expression of alpha7 mRNA and receptor protein in human postmortem brain tissue was examined by in situ hybridization and [125I]-alpha-bungarotoxin autoradiography, respectively, with particular emphasis on regions associated with sensory processing. Regions with high levels of both alpha7 gene expression and [125I]-alphaBTX binding include the nucleus reticularis of the thalamus, the lateral and medial geniculate bodies, the basilar pontine nucleus, the horizontal limb of the diagonal band of Broca, the nucleus basalis of Meynert, and the inferior olivary nucleus. High-to-moderate levels of alpha7 probe hybridization were also seen in the hippocampus and the cerebral cortex; however, there was a reduced or variable degree of [125I]-alphaBTX binding in these regions compared with the level of probe hybridization. In most brain regions, [125I]-alphaBTX binding was localized to neuronal cell bodies similar in morphology to those that exhibited alpha7 hybridization, suggesting that the high-affinity [125I]-alphaBTX binding sites in the human brain are likely to be principally composed of alpha7 receptor subtypes.

Smoking and mental illness

Patients with mental illness have a higher incidence of smoking than the general population and are the major consumers of tobacco products. This population includes subjects with schizophrenia, manic depression, depression, posttraumatic stress disorder (PTSD), attention-deficit disorder (ADD), and several other less common diseases. Smoking cessation treatment in this group of patients is difficult, often leading to profound depression. Several recent findings suggest that increased smoking in the mentally ill may have an underlying biological etiology. The mental illness schizophrenia has been most thoroughly studied in this regard. Nicotine administration normalizes several sensory-processing deficits seen in this disease. Animal models of sensory deficits have been used to identify specific nicotinic receptor subunits that are involved in these brain pathways, indicating that the alpha 7 nicotinic receptor subunit may play a role. Genetic linkage in schizophrenic families also supports a role for the alpha 7 subunit with linkage at the alpha 7 locus on chromosome 15. Bipolar disorder has some phenotypes in common with schizophrenia and also exhibits genetic linkage to the alpha 7 locus, suggesting that these two disorders may share a gene defect. The alpha 7 receptor is decreased in expression in schizophrenia. [(3)H]-Nicotine binding studies in postmortem brain indicate that high-affinity nicotinic receptors may also be affected in schizophrenia.

Clinical and bacteriological responses to three antibiotic regimens for acute exacerbations of cystic fibrosis: ticarcillin-tobramycin, azlocillin-tobramycin, and azlocillin-placebo

In a randomized, double-blind study, cystic fibrosis patients 11-30 years of age with an acute exacerbation of their pulmonary disease were treated with either ticarcillin-tobramycin, azlocillin-tobramycin, or azlocillin-placebo for 10 days. There was significant improvement in Shwachman scores and pulmonary function tests. Concentrations of sputum bacteria were significantly reduced, but after therapy patients had a mean of 10(7) bacteria/ml of sputum. Pseudomonas was transiently eliminated in only one patient. The three regimens had similar impacts on pulmonary function and sputum bacterial concentration. Antibiotic resistance was noted more frequently in the azlocillin-placebo group, but this trend was not statistically significant. Improvement in pulmonary function did not correlate with bacteriological response. Four weeks after discharge, 62% of the improvement in forced expiratory volume in one second and 75% of the improvement in vital capacity remained, but concentrations of sputum bacteria had returned to pretreatment levels, and antibiotic-resistant bacteria persisted.

Perfluorocarbon liquids in ophthalmology

Perfluorocarbon liquids have been used to facilitate surgery in a wide variety of conditions, including proliferative vitreoretinopathy, giant retinal tears, drainage of suprachoroidal hemorrhages, diabetic traction, retinal detachments with a rhegmatogenous component, dislocated crystalline or intraocular lenses, and retinal detachment associated with choroidal coloboma. The clarity of perfluorocarbon liquids, with a refractive index close to that of water, allows the use of a conventional contact lens for vitreous surgery while the low viscosity facilitates tissue manipulation, injection, and removal. All perfluorocarbon liquids when used as tamponading agents can compress and disorganize the retina. This "toxicity" is a physical effect rather than chemical toxicity and depends upon the amount of perfluorocarbon liquid injected. Perfluorocarbon liquids are not tolerated in the anterior chamber, causing corneal edema within 2-3 days at the site of contact.

Functional differences in the multiple hemocyanins of the horseshoe crab, Limulus polyphemus L

Hemocyanin in the hemolymph of the horseshoe crab, Limulus polyphemus L., is a high-molecular-weight copper protein which binds oxygen cooperatively and shows a higher oxygen affinity at pH 7 than at pH 9. Treatment with EDTA (ethylenediaminetetra-acetate) disaggregates the hemocyanin molecules and abolishes both the reverse Bohr effect and cooperative oxygen binding. Chloride ions interact with the EDTA-treated material and, in the presence of saturating amounts of NaCl, a reverse Bohr effect is restored, but cooperativity is not. The EDTA-treated hemocyanin contains at least five electrophoretically distinct hemocyanins. These hemocyanins have similar molecular weights (about 66,000) but are functionally dissimilar. They have different oxygen affinities and different responses to chloride ions. The effect of chloride ions on unfractionated hemocyanin is due to pH-dependent chloride interactions with only two of the five hemocyanin components. The functional differences between the hemocyanin components may provide Limulus with a valuable respiratory flexibility in its interaction with the environment. The kinetics of oxygen combination and dissociation for the various hemocyanin preparations show that variations in the rate of oxygen dissociation are primarily responsible for the observed differences in oxygen affinity. The rate of oxygen dissociation varies 20-fold under conditions where the apparent rate of oxygen combination shows less than a 2-fold variation. Cooperative interactions in the untreated hemocyanin are most obvious in the "off" reaction, which increases in rate as successive oxygen molecules are released.

A comparison of bone scintigraphy and MRI in the early diagnosis of the occult scaphoid waist fracture

OBJECTIVE

To determine the accuracy of MRI in the assessment of the radiographically occult scaphoid fracture.

DESIGN

This prospective study compared the sensitivity and specificity of MRI for detection of radiographically occult scaphoid fractures with bone scintigraphy (BS), the currently accepted imaging modality of choice. Consecutive patients with clinical signs of a scaphoid injury but no evidence of fracture on plain radiographs at presentation and after 7-10 days were evaluated by MRI and BS. All images were reported in masked fashion and the sensitivities and specificities of the imaging modalities determined. All patients with a scaphoid fracture demonstrated by MRI or BS were followed for at least a year after injury.

PATIENTS

Forty-three subjects (aged 12-74 years) had both MRI and BS carried out on average 19 days from the injury date.

RESULTS AND CONCLUSIONS

Six patients (14%) had scaphoid waist fractures. There were other bony injuries in a further six. In 40 patients there was agreement between the BS and MRI findings. In three cases there was discrepancy between the imaging modalities; in all three MRI was found to be the more sensitive and specific. MRI could become the investigation of choice for this injury.

Siphonodictidine, a Metabolite of the Burrowing Sponge Siphonodictyon sp. That Inhibits Coral Growth

Siphonodictidine is the major secondary metabolite of an undescribed Indo-Pacific sponge Siphonodictyon sp. that burrows into living coral heads. The structure of siphonodictidine was determined from spectral data. Laboratory bioassays suggest that siphonodictidine and, by analogy, the siphonodictyals from S. coralliphagum are responsible for maintaining zones of dead coral polyps around the oscular chimneys of these sponges.

Centromere identity in Drosophila is not determined in vivo by replication timing

Centromeric chromatin is uniquely marked by the centromere-specific histone CENP-A. For assembly of CENP-A into nucleosomes to occur without competition from H3 deposition, it was proposed that centromeres are among the first or last sequences to be replicated. In this study, centromere replication in Drosophila was studied in cell lines and in larval tissues that contain minichromosomes that have structurally defined centromeres. Two different nucleotide incorporation methods were used to evaluate replication timing of chromatin containing CID, a Drosophila homologue of CENP-A. Centromeres in Drosophila cell lines were replicated throughout S phase but primarily in mid S phase. However, endogenous centromeres and X-derived minichromosome centromeres in vivo were replicated asynchronously in mid to late S phase. Minichromosomes with structurally intact centromeres were replicated in late S phase, and those in which centric and surrounding heterochromatin were partially or fully deleted were replicated earlier in mid S phase. We provide the first in vivo evidence that centromeric chromatin is replicated at different times in S phase. These studies indicate that incorporation of CID/CENP-A into newly duplicated centromeres is independent of replication timing and argue against determination of centromere identity by temporal sequestration of centromeric chromatin replication relative to bulk genomic chromatin.

Surgical anatomy of the infratemporal fossa: the styloid diaphragm revisited

INTRODUCTION

The infratemporal fossa (ITF) gives passage to most major cerebral vessels and cranial nerves. Dissection of the ITF is essential in many of the lateral cranial base approaches and in exposure of the high cervical internal carotid artery (ICA). We reviewed the surgical anatomy of this region.

METHODS

Direct foraminal measurements were made in seven dry skulls (14 sides), and the relationship of these foramina to each other and various landmarks were determined. Ten ITF dissections were performed using a preauricular subtemporal-infratemporal approach. Preliminary dissections of the extracranial great vessels and structures larger than 1 cm were performed using standard macroscopic surgical techniques. Dissection of all structures less than 1 cm was conducted using microsurgical techniques and instruments, including the operating microscope. The anatomic relationships of the muscles, nerves, arteries, and veins were carefully recorded, with special emphasis regarding the relationship of these structures to the styloid diaphragm. The dissection was purely extradural.

RESULTS

The styloid diaphragm was identified in all specimens. It divides the ITF into the prestyloid region and the retrostyloid region. The prestyloid region contains the parotid gland and associated structures, including the facial nerve and external carotid artery. The retrostyloid region contains major vascular structures (ICA, internal jugular vein) and the initial exocranial portion of the lower Cranial Nerves IX through XII. Landmarks were identified for the different cranial nerves. The bifurcation of the main trunk of the facial nerve was an average of 21 mm medial to the cartilaginous pointer and an average of 31 mm medial to the tragus of the ear. The glossopharyngeal nerve was found posterior and lateral to stylopharyngeus muscle in nine cases and medial in only one. The vagus nerve was consistently found in the angle formed posteriorly by the ICA and the internal jugular vein. The spinal accessory nerve crossed anterior to the internal jugular vein in five cases and posterior in another five cases. It could be located as it entered the medial surface of the sternocleidomastoid muscle 28 mm (mean) below the mastoid tip. The hypoglossal nerve was most consistently identified as it crossed under the sternocleidomastoid branch of the occipital artery 25 mm posterior to the angle of the mandible and 52 mm anterior and inferior to the mastoid tip.

CONCLUSION

The styloid diaphragm divides the ITF into prestyloid and retrostyloid regions and covers the high cervical ICA. Using landmarks for the exocranial portion of the lower cranial nerves is useful it identifying them and avoiding injury during approaches to the high cervical ICA, the upper cervical spine, and the ITF.

Transfusion-related sepsis after prolonged platelet storage

The antecubital fossa venipuncture site in frequent blood donors can become scarred or "dimpled" and colonized with surface and deep bacteria that are not sterilized by standard iodophor preparation techniques. These microorganisms can be introduced into blood or platelets at the time of donation. Recent advances that permit the prolonged storage of platelets at room temperature before transfusion allow proliferation of these contaminating bacteria, particularly gram-positive microorganisms. Documented are three episodes of platelet contamination with gram-positive organisms and four cases of sepsis in recipients of these platelets, which were obtained through the "dimpled" site of a single donor and stored for at least 80 hours at 22 degrees C before transfusion. In contrast, platelets harvested from this donor's "dimpled" site and stored for not more than 50 hours were transfused to 25 patients without complication. Therefore, the extended storage of platelets at 22 degrees C prior to transfusion demands strict awareness of any possible sources of extrinsic contamination, since gram-positive bacteria can proliferate under these conditions and result in infectious complications in recipients.

Nosocomial sepsis associated with interleukin-2

STUDY OBJECTIVE

To determine the incidence, clinical magnitude, and risk factors for nosocomial bacteremia in patients given interleukin-2 with or without (+/-) lymphokine activated killer (LAK) cells for cancer immunotherapy.

DESIGN

Cohort study.

SETTING

Clinical study unit of tertiary medical center.

PATIENTS

All patients entering the interleukin-2 +/- LAK cancer immunotherapy protocol during a 28-month period. Control groups were patients in a surgical intensive care unit, patients receiving total parenteral nutrition, and patients with solid tumors.

MEASUREMENTS AND MAIN RESULTS

Twenty of 107 (19%) interleukin-2-treated patients developed sepsis; in 12 of these patients, sepsis was intravenous catheter-associated. The bacteremia rate among patients receiving total parenteral nutrition, in the surgical intensive care unit, or having solid tumors was 2.8%, 4.1%, and 1.9%, respectively. Staphylococcus aureus was the pathogen in 13 courses; Staphylococcus epidermidis, in 5; and Escherichia coli, in 2. Two patients died; three developed suppurative thrombophlebitis; one developed septic arthritis; one, septic arterial aneurysm; and one, peritonitis with probable meningitis. Colonization with S. aureus increased the risk of S. aureus bacteremia 6.3-fold (95% CI, 2.8 to 14.5; P less than 0.001); skin desquamation at the catheter site increased the relative risk 2.0-fold (95% CI, 1.3 to 3.1; P = 0.031). Both colonization with S. aureus and skin desquamation increased the relative risk of S. aureus bacteremia 14.5-fold (95% CI, 4.1 to 50.9; P less than 0.0001).

CONCLUSIONS

Staphylococcal bacteremia is more frequent in patients receiving interleukin-2 therapy and is associated with substantial morbidity and toxic skin reactions.

[(3)H]Nicotine binding in peripheral blood cells of smokers is correlated with the number of cigarettes smoked per day

The principal sites for biological action of tobacco products are thought to be the nicotinic acetylcholine receptors (nAChR). Nicotinic receptor subunit genes, therefore, represent an important gene family for study in nicotine addiction. They are localized in both brain and in the periphery. In brain these receptors appear to function as modulators of synaptic transmission; the function of peripheral receptors is not known. Nicotinic receptor levels in human brain are regulated by smoking in a dose-dependent manner. In peripheral blood, nicotinic receptors are present on both lymphocytes and polymorphonuclear cells (PMN). We have compared [(3)H]nicotine binding in PMN isolated from smokers and non-smokers. [(3)H]nicotine binding was increased in smokers and was correlated, as in brain, with tobacco use. Expression of both mRNA and protein in lymphocytes and PMN, for a subset of nicotinic receptor subunits, suggests that these cell types contain both alpha4beta2 and alpha3beta4 receptors.

The P50 auditory event-evoked potential in adult attention-deficit disorder: comparison with schizophrenia

BACKGROUND

Attention-deficit/hyperactivity disorder (ADHD) and schizophrenia are both conceptualized as disorders of attention. Failure to inhibit the P50 auditory event-evoked response, extensively studied in schizophrenia, could also occur in ADHD patients, if these two illnesses have common underlying neurobiological substrates.

METHODS

This study examined the inhibition of the P50 auditory event-evoked potential in 16 unmedicated adults with ADHD, 16 schizophrenic outpatients, and 16 normal control subjects. Auditory stimuli were presented in a paired stimulus, conditioning-testing paradigm.

RESULTS

The amplitude of initial or conditioning P50 response did not differ between the three groups; however, significant effects of psychiatric diagnosis on the amplitude of the test response and the ratio of the test to the conditioning response amplitudes were observed. Schizophrenic patients' P50 ratios and test amplitudes were higher than both the ADHD and normal groups.

CONCLUSIONS

Adults with ADHD do not have the inhibitory deficit seen in patients with schizophrenia, suggesting that the mechanism of attentional disturbance in the two illnesses may be fundamentally different.

Transmission of violet and blue light through conventional (layered) and bulk cured resin-based composites

OBJECTIVES

This study measured the transmission of light in the 'violet' (350≤λ≤425nm) and 'blue' (425<λ≤550nm) spectral ranges from a polywave(®) LED curing light through different thicknesses of four commercial, resin-based composites (RBCs).

MATERIAL AND METHODS

Samples of conventional layered RBCs (Tetric EvoCeram A2, Filtek Supreme Ultra A2B), and bulk-curing resins (Tetric EvoCeram Bulk Fill IVA, and SureFil SDR Flow U) were prepared. Three samples of each RBC were made at thicknesses of 0.1, 0.7, 1, 2, and 4-mm. The uncured RBC specimens were affixed at the entrance aperture of a 6-inch integrating sphere and light-cured once for 20s using a polywave(®) LED curing light (Bluephase G2) on its high power setting. The spectral radiant power transmitted through each RBC in the 'violet' and 'blue' regions was measured using a fiberoptic spectrometer.

RESULTS

As RBC thickness increased, an exponential attenuation of transmitted light was measured (R(2)>0.98). Attenuation was greater for the 'violet' than for the 'blue' spectral regions. At the light tip, the violet light component represented 15.4% of the light output. After passing through 4-mm of RBC, the violet light represented only between 1.2-3.1% of the transmitted light depending on the RBC. Depending on RBC, approximately 100mW from the Bluephase G2 was transmitted through 0.1-mm of RBC in the 'violet' range, falling at most to 11mW after passing through 2-mm of RBC, and to only 2mW at 4-mm depth.

CONCLUSIONS

Increasing RBC thickness results in an exponential decrease in light transmission. This attenuation is RBC-dependent with shorter wavelengths (violet) attenuated to a greater extent than longer wavelengths (blue).

CLINICAL RELEVANCE

Despite the increased translucency of bulk curing RBCs, spectral radiant power shorter than 425nm from a curing light is unlikely to be effective at a depth of 4-mm or more.

Hemoglobins and hemocyanins: comparative aspects of structure and function

Comparative studies of protein structure and function can be quite interesting by themselves, and even more interesting when interpreted with respect to an animal's physiology. In the case of fish hemoglobins, some success in the latter has been achieved but there are still many unsolved problems. It appears that comparative physiology and biochemistry have entered an era where results from comparative studies can shed a great deal of light on biochemical mechanisms in general. The trout hemoglobin system is an example. Distinctive hemoglobins in this system are presently being used as high resolution probes of the ligand-binding mechanism. Characterization of the multiple, structurally distinct subunits of the 60S Limulus hemocyanin molecule may similarly aid in understanding its function. Our studies suggest the possibility of using Limulus hemocyanin and other hemocyanins as structural homologs and analogs of more complex macromolecular arrays. The rapid development of molecular structural data from X-ray crystallographers combined with the vast data of comparative physiology and biochemistry makes this one of the most exciting areas in present day science.

Comparison of acellular and whole-cell pertussis-component diphtheria-tetanus-pertussis vaccines in infants. The APDT Vaccine Study Group

In a multicenter, double-blind, randomized, longitudinal study, 252 children received licensed Lederle diphtheria-tetanus toxoids and pertussis vaccine adsorbed (DTP) at 2, 4, and 6 months of age, and 245 children received a DTP vaccine with the Lederle/Takeda acellular pertussis component (APDT) at the same ages. Both groups of children received APDT vaccine at 18 months of age. After each of the first three immunizations, APDT vaccine recipients had fewer local and systemic reactions than did DTP vaccinees. Reactions after the 18-month APDT vaccination were minimal in severity regardless of the vaccine previously received. Antibody responses to lymphocytosis-promoting factor and agglutinogens were more pronounced in DTP recipients; however, APDT recipients had a better serologic response to filamentous hemagglutinin, and responses to the 69K protein were equivalent. This APDT vaccine produces fewer reactions than the standard whole-cell DTP vaccine. The protective significance of the serologic responses to the APDT vaccine is unknown, but the greater response to filamentous hemagglutinin and equivalent response to the 69K protein compared with those to DTP vaccine seem promising.

Urea tolerance as a molecular adaptation of elasmobranch hemoglobins

Urea is maintained at moderately high concentrations in the blood and tissues of marine elasmobranchs. Functional properties of the hemoglobins fromn several elasmobranch species are unaffected by urea concentrations as high as 5 molar. This in. sensitivity to urea, which is not observed with human hemoglobin, is accompanied by an increased sensitivity to sodium chloride.

Prognostic role of serum prostatic acid phosphatase for 103Pd-based radiation for prostatic carcinoma

PURPOSE

To establish the prognostic role of serum enzymatic prostatic acid phosphatase (PAP) in patients treated with palladium (103Pd) and supplemental external beam irradiation (EBRT) for clinically localized, high-risk prostate carcinoma.

METHODS AND MATERIALS

One hundred twenty-four consecutive patients with Stage T2a-T3 prostatic carcinoma were treated from 1992 through 1995. Each patient had at least one of the following risk factors for extracapsular disease extension: Stage T2b or greater (100 patients), Gleason score 7-10 (40 patients), pretreatment prostate specific antigen (PSA) >15 ng/ml (32 patients), or elevated serum PAP (25 patients). Patients received 41 Gy conformal EBRT to a limited pelvic field, followed 4 weeks later by a 103Pd boost (prescription dose 80 Gy). Biochemical failure was defined as a PSA greater than 1 ng/ml (normal <4 ng/ml).

RESULTS

The overall, actuarial freedom from biochemical failure at 4 years after treatment was 79%. In Cox-proportional hazard multivariate analysis, the strongest predictor of failure was elevated pretreatment acid phosphatase (p = 0.02), followed by Gleason score (p = 0.1), and PSA (p = 0.14).

CONCLUSION

PAP was the strongest predictor of long-term biochemical failure. It may be a more accurate indicator of micrometastatic disease than PSA, and as such, we suggest that it be reconsidered for general use in radiation-treated patients.