Contact analysis of a posterior cervical spine plate using a three-dimensional canine finite element model

The development of a three-dimensional finite element model of a posteriorly plated canine cervical spine (C3-C6) including contact nonlinearities is described. The model was created from axial CT scans and the material properties were derived from the literature. The model demonstrated sufficient accuracy from the results of a mesh convergence test. Significant steps were taken toward establishing model validation by comparison of plate surface strains with a posteriorly plated canine cervical spine under three-point bending. This model was developed to better characterize the contact pressures at the various interfaces under average physiologic canine loading. The analysis showed that the screw-plate interfaces had the highest values of all the mechanical parameters evaluated.

Sensory irritation and multiple chemical sensitivity

Many of the symptoms described in Sick Building Syndrome (SBS) and multiple chemical sensitivity (MCS) resemble the symptoms known to be elicited by airborne irritant chemicals. Irritation of the eye, nose, and throat is common to SBS, MCS, and sensory irritation (SI). Difficulty of breathing is often seen with SBS, MCS, and pulmonary irritation (PI). We therefore asked the question: can indoor air pollutants cause SI and/or PI? In laboratory testing in which mice breathed the dilute volatile emissions of air fresheners, fabric softeners, colognes, and mattresses for 1 h, we measured various combinations of SI and PI as well as airflow decreases (analogous to asthma attacks). Air samples taken from sites associated with repeated human complaints of poor air quality also caused SI, PI, and airflow limitation (AFL) in the mice. In previous publications, we have documented numerous behavior changes in mice (which we formally studied with a functional observational battery) after exposure to product emissions or complaint site air; neurological complaints are a prominent part of SBS and MCS. All together, these data suggest that many symptoms of SBS and MCS can be described as SI, PI, AFL, and neurotoxicity. All these problems can be caused by airborne irritant chemicals such as those emitted by common commercial products and found in polluted indoor air. With some chemical mixtures (e.g., emissions of some fabric softeners, disposable diapers, and vinyl mattress covers) but not others (e.g., emissions of a solid air freshener), the SI response became larger (2- to 4-fold) when we administered a series of two or three 1-h exposures over a 24-h period. Since with each exposure the intensity of the stimulus was constant yet the magnitude of the response increased, we concluded that there was a change in the sensitivity of the mice to these chemicals. The response was not a generalized stress response because it occurred with only some mixtures of irritants and not others; it is a specific response to certain mixtures of airborne chemicals. This is one of the few times in MCS research that one can actually measure both the intensity of the stimulus and the magnitude of the response and thus be allowed to discuss sensitivity changes. The changing SI response of the mice might serve as a model of how people develop increasing sensitivity to environmental pollutants. Intensive study of this system should teach us much about how people respond to and change sensitivity to airborne irritant chemicals.

Affinity NMR: decoding DNA binding

We have shown that affinity NMR can be used to edit a NMR spectrum so that ligands that have affinity to DNA can be observed in the presence of other nonbinding molecules. Diffusion encoded spectroscopy (DECODES) can be used to identify the binding ligands. We were able to identify Hoechst 33342 as binding to the Drew-Dickerson dodecamer d(CGCGAATTCGCG)2 in the presence of the nonbinding molecules adenine, adenosine, and thiamine. Affinity NMR appears to be readily applicable to DNA systems for the following reasons. (1) The relaxation rate of the DNA oligonucleotides is favorable, thus the signal intensity loss due to relaxation is not severe. (2) A comparison of the patterns of the DNA cross-peaks upon binding in the two-dimensional total correlation spectroscopy and correlation spectroscopy spectrum are easily performed, and the ligand signals in the two-dimensional DECODES spectrum can be readily identified. (3) The aromatic part of the DNA spectrum is devoid of 2D cross-peaks in these correlation spectra, greatly facilitating the interpretation of the bound ligand in the DECODES spectrum.

Heterodyning technique to improve performance of delta-sigma-based beamformers

Delta-sigma (DeltaSigma) modulators can implement a simpler digital ultrasound beamformer than can traditional architectures based on multi-bit analog-to-digital converters (A/D). The signal-to-noise ratio (SNR) of the DeltaSigma modulators, however, suffers from limited oversampling ratios. To improve the SNR of each channel, a mixing signal heterodynes narrowband signals to lower frequencies where the baseband DeltaSigma modulator performs better. Noise figure analyses are presented that illustrate the effectiveness of this technique in improving noise performance. Also, spectral Doppler and color flow simulations are presented that realistically emulate a 32 channel oversampled beamformer and compare these results with traditional and ideal systems.

Delta-sigma oversampled ultrasound beamformer with dynamic delays

The principles of oversampling are exploited in a simple beamforming architecture using a single bit delta-sigma (DeltaC) analog to digital converter (A/D) on every channel. The high sampling rate required for the single bit A/D provides adequate delay accuracy for high quality beamforming using elementary sample manipulations. Images produced with this beamformer exhibit significant artifacts directly related to dynamic focusing. However, a simple digital recording technique following delays permits dynamically focused beamforming without degrading image quality. The simplicity of this beamformer compared to conventional methods may facilitate very large channel count or low power beamformers suitable for 1.5-D arrays or portable scanners.

Effect of a commercial competitive exclusion culture (Preempt) on mortality and horizontal transmission of Salmonella gallinarum in broiler chickens

A commercial competitive exclusion (CE) culture (PREEMPT) was evaluated for its ability to decrease mortality during the first 10-12 days posthatch resulting from the causative agent of fowl typhoid, Salmonella gallinarum. In the first experiment, chicks provided the CE culture on day of hatch and challenged with 10(5) S. gallinarum on day 3 had a significant decrease in mortality compared with non-CE-treated S. gallinarum-challenged chicks in all four replicates. Mortality for control chicks when averaged across all four replicates was 74% compared with 7.5% for the CE-treated chicks. A second experiment was performed that was designed to measure the efficacy of the CE culture in decreasing the horizontal transmission of this pathogen from infected to uninfected chicks when commingled. Day-of-hatch chicks that were directly infected (seeders) with 10(5) S. gallinarum and provided no CE culture averaged 86% S. gallinarum organ positive and 80% mortality during the first 12 days posthatch across four replicates. Untreated contact (not directly infected) chicks that were commingled with the seeder chicks averaged 84% S. gallinarum organ positive and 54% mortality, and the commingled CE-treated contact chicks (provided CE culture on day of hatch) average 35% S. gallinarum organ positive and 9% mortality during the same time period. These results are of importance to the poultry industry in geographic areas where poultry production is adversely affected by fowl typhoid and indicate that treating newly hatched chicks with this commercial CE culture may be a novel way of decreasing economic losses associated with this highly pathogenic organism.

Halicephalobus gingivalis (Stefanski, 1954) from a fatal infection in a horse in Ontario, Canada with comments on the validity of H. deletrix and a review of the genus

Although the original description given by Stefanski (1954) was satisfactory, Anderson & Bemrick (1965), in describing H. deletrix (= Micronema deletrix), claimed Stefanski's description was "inadequate" and the species a "species inquirenda". Thus, infections in horses and humans have been assigned to H. deletrix. We believe the species reported in horses and humans is H. gingivalis and that H. deletrix is its synonym. H. gingivalis is separated herein from forms found free-living. The genital tract in the advanced fourth stage of H. gingivalis is didelphic and amphidelphic and terminal ends of the horns are reflected, the anterior one ventrally, the posterior one dorsally. In the adult parthenogen the latter forms a short ovary, whereas most of the anterior horn forms a combined uterus-oviduct as a receptacle for a single large egg which is laid in the 2-cell or multi-cell stage. Eggs in the 2-cell stage embryonated to larvae in 17 hours at 28 degrees C but did not hatch until an additional 24 hours. First-stage larvae were unusually large and variable in length (136-199 microns x = 168). Inactive third-stage larvae were 180-240 microns (x = 203) in length. The possible route of infection in horses and humans is briefly discussed.

Experimental and natural infection of early weaned pigs with Salmonella choleraesuis

A model for experimental and natural infection of early weaned pigs with Salmonella choleraesuis, the aetiologic agent of swine paratyphoid, has been developed. An oral dose of 10(8) colony forming units (cfu) of S choleraesuis caused 100 per cent infection of 10 pigs inoculated, as indicated by recovery of the challenge organism from ileocolic lymph nodes collected at necropsy seven days post challenge. Seven of the pigs were observed shedding S choleraesuis at least once post S choleraesuis challenge. The cumulative incidence of shedding was 30 per cent and was sufficient to infect four of 10 pigs exposed naturally. Oral challenges with less than 10(8) cfu S choleraesuis were less effective in infecting early weaned pigs and did not result in natural transmission.

Acute toxic effects of fragrance products

To evaluate whether fragrance products can produce acute toxic effects in mammals, we allowed groups of male Swiss-Webster mice to breathe the emissions of five commercial colognes or toilet water for 1 h. We used the ASTM-E-981 test method to evaluate sensory irritation and pulmonary irritation. We used a computerized version of this test to measure the duration of the break at the end of inspiration and the duration of the pause at the end of expiration. Decreases in expiratory flow velocity indicated airflow limitation. We subjected the mice to a functional observational battery to probe for changes in nervous system function. The emissions of these fragrance products caused various combinations of sensory irritation, pulmonary irritation, decreases in expiratory airflow velocity, as well as alterations of the functional observational battery indicative of neurotoxicity. Neurotoxicity was more severe after mice were repeatedly exposed to the fragrance products. Evaluation of one of the test atmospheres with gas chromatography/mass spectrometry revealed the presence of chemicals for which irritant and neurotoxic properties had been documented previously. In summary, some fragrance products emitted chemicals that caused a variety of acute toxicities in mice.

Carnitine palmitoyltransferase: a viable target for the treatment of NIDDM?

Inhibition of fatty acid oxidation is well recognized as a potentially effective mechanism for controlling glycemia in non-insulin-dependent diabetes mellitus (NIDDM). However, a direct targeting of inhibition of the intramitochondrial beta-oxidation pathway or an indirect modulation of fatty acid oxidation by inhibition of substrate release from adipose stores has been fraught with lack of efficacy, unacceptable side-effects or both. Focus has therefore recently been directed towards the carnitine palmitoyltransferase (CPT) system, a three-component system necessary for the transfer of long-chain fatty acids into the intramitochondrial matrix. This article will briefly review the background for fatty acid oxidation inhibition in NIDDM and then focus on the progress in the biological understanding and drug discovery targeting of the CPT system for the treatment of NIDDM. Based upon the review, it is concluded that mechanism-based hepatic and myocardial toxicities in normal animals and a potential for a lack of human efficacy may pose insurmountable hurdles for the development of CPT inhibitors for the treatment of NIDDM.

Hypoglycemic effects of a novel fatty acid oxidation inhibitor in rats and monkeys

Increased fatty acid oxidation contributes to hyperglycemia in patients with non-insulin-dependent diabetes mellitus. To improve glucose homeostasis in these patients, we have designed a novel, reversible inhibitor of carnitine palmitoyl-transferase I (CPT I) that potently inhibits fatty acid oxidation. SDZ-CPI-975 significantly lowered glucose levels in normal 18-h-fasted nonhuman primates and rats. In rats, glucose lowering required fatty acid oxidation inhibition of > or = 70%, as measured by beta-hydroxybutyrate levels, the end product of beta-oxidation. In cynomolgus monkeys, comparable glucose lowering was achieved with more modest lowering of beta-hydroxybutyrate levels. SDZ-CPI-975 did not increase glucose utilization by heart muscle, suggesting that CPT I inhibition with SDZ-CPI-975 would not induce cardiac hypertrophy. This was in contrast to the irreversible CPT I inhibitor etomoxir. These results demonstrate that SDZ-CPI-975 effectively inhibited fatty acid oxidation and lowered blood glucose levels in two species. Thus reversible inhibitors of CPT I represent a class of novel hypoglycemic agents that inhibit fatty acid oxidation without inducing cardiac hypertrophy.

Acute filariasis in a springhaas

A 2-yr old Springhaas (Pedetes capensis; Pedetidae, Rodentia) imported into the USA from the Republic of South Africa was severely debilitated as the result of abberant migrations of adult Filaria versterae (Filarioidea: Filariidae) normally confined to the subcutaneous tissues of this host in Africa. Some nematodes invaded the peritoneal and thoracic cavities, the pericardial sac and the lungs. Invasion of the lungs resulted in life-threatening respiratory distress necessitating euthanasia. Filaria versterae is redescribed.

Toxic effects of air freshener emissions

To evaluate whether emissions of a commercial air freshener produced acute toxic effects in a mammalian species, the authors allowed male Swiss-Webster mice to breathe the emissions of one commercial-brand solid air freshener for 1 h. Sensory irritation and pulmonary irritation were evaluated with the ASTM-E-981 test. A computerized version of this test measured the duration of the break at the end of inspiration and the duration of the pause at the end of expiration--two parameters subject to alteration via respiratory effects of airborne toxins. Measurements of expiratory flow velocity indicated changes in airflow limitation. The authors then subjected mice to a functional observational battery, the purpose of which was to probe for changes in nervous system function. Emissions of this air freshener at several concentrations (including concentrations to which many individuals are actually exposed) caused increases in sensory and pulmonary irritation, decreases in airflow velocity, and abnormalities of behavior measured by the functional observational battery score. The test atmosphere was subjected to gas chromatography/mass spectroscopy, and the authors noted the presence of chemicals with known irritant and neurotoxic properties. The Material Safety Data Sheet for the air freshener indicated that there was a potential for toxic effects in humans. The air freshener used in the study did not diminish the effect of other pollutants tested in combination. The results demonstrated that the air freshener may have actually exacerbated indoor air pollution via addition of toxic chemicals to the atmosphere.

Stress analysis of halo pin insertion by non-linear finite element modeling

Halo fixation is associated with a high complication rate. The most common complications are loose pins and pin site infections believed to be exacerbated by loose pins. Although pin designs and the technique of pin insertion have changed little in over 30 years, the pin/skull mechanics are poorly understood. Halo pin insertion was modeled using nonlinear finite element analyses to determine the stress distribution in the human skull underlying and surrounding the point of pin fixation. Model validity was established by comparing pin insertion depth and the profile of the hole generated in the bone to the results of experimental mechanical tests. The region surrounding the pin tip within 1 mm was found to undergo plastic deformation and compressive loading in excess of the compressive yield strength of cortical bone. The implication is that damaged bone in this region is responsible for the high incidence of halo pin loosening. Resorption or migration of bone particles with periodic relief of compression in this region due to daily cyclic forces might result in an enlarged pin site and eventually, a loose pin.

Characteristics of a nitropropanol-metabolizing bacterium isolated from the rumen

We report some characteristics of a ruminal bacterium (strain NPOH1) that metabolizes 3-nitropropanol, the toxic principle of various milk vetchs that are distributed worldwide. The gram-positive bacterium was nonmotile and did not produce spores. Growth of strain NPOH1 occurred under anaerobic conditions and was supported by the electron acceptors 3-nitropropanol, 3-nitropropionate, nitrate, 2-nitropropanol, nitroethane, nitroethanol, or 3-nitro-1-propyl-beta-D-glucopyranoside (miserotoxin). Other potential electron acceptors, namely sulfate, sulfite, azide, chlorate, perchlorate, nitrite, fumarate, 2-nitrobutane, or nitrobenzene, did not support growth. Formate, lactate, and H2 stimulated growth of strain NPOH1 in the presence of the appropriate nitrocompound, whereas a variety of other potential H2 donors did not. When grown in medium containing both nitrate and either 3-nitropropanol or 3-nitropropionate, nitrate was the preferred acceptor. Strain NPOH1 reduced nitrate to nitrite and, when grown with excess reductant, nitrite was further reduced to ammonia. The products formed during the metabolism of 3-nitropropanol and 3-nitropropionate by mixed ruminal populations, 3-aminopropanol and beta-alanine, were not found in culture fluids of strain NPOH1. Analysis of total cellular fatty acid profiles and of the mole percent guanine plus cytosine suggests that strain NPOH1 is a novel bacterium. The capacity of strain NPOH1 to metabolize 3-nitropropanol suggests that this organism may play an important role in detoxification of 3-nitropropanol in the rumen.

Reflex sympathetic dystrophy/conversion disorder

Both reflex sympathetic dystrophy (RSD) and conversion disorder are difficult to diagnose and treat. The following article depicts a situation in which diagnosis presents a particular challenge and suggests ways of applying both medicine and psychology in the treatment of this complex problem.

Local delivery of chemotherapy and concurrent external beam radiotherapy prolongs survival in metastatic brain tumor models

Local chemotherapy with biodegradable polymers prolongs survival with minimal morbidity in patients with intracranial high-grade gliomas. However, use of local chemotherapy for metastatic brain tumors has not been defined. We studied the safety and the efficacy of locally delivered chemotherapy with and without concurrent radiation therapy in treating tumors that frequently metastasize to the brain. The chemotherapeutic agents 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU), carboplatin, and camptothecin were incorporated into controlled-release polymers and tested individually against intracranial challenges with one of four tumors (lung carcinoma, renal cell carcinoma, colon carcinoma, and melanoma). For each combination of drug and tumor type, four groups were tested: (a) empty polymer (no drug); (b) external beam radiotherapy (XRT) alone; (c) local chemotherapy from biodegradable polymer alone; and (d) local chemotherapy and XRT together. Polymers were implanted 5 days after tumor inoculation; XRT was given on days 7-9 (300 cGy/day). BCNU and XRT together were effective against all four tumors. BCNU polymer alone significantly prolonged survival in mice with intracranial melanoma or renal cell carcinoma. Carboplatin alone was effective against both melanoma and colon carcinoma and in combination with XRT against colon and renal cell carcinomas. Camptothecin was effective only with XRT against melanoma. These studies demonstrate that local delivery of chemotherapy with concurrent radiation therapy is safe and can significantly prolong survival in models of common intracranial metastatic tumors. Concurrent use of local chemotherapy with standard XRT appears to be more effective than either treatment alone. Local chemotherapy may also be of benefit to patients who have previously received maximal cranial irradiation but suffer an intracranial recurrence.

Enrichment and isolation of a nitropropanol-metabolizing bacterium from the rumen

A bacterium capable of metabolizing nitropropanol, nitropropionate, and nitrate has been isolated from a mixed ruminal population enriched for enhanced rates of nitropropanol metabolism. The numbers of nitropropanol-metabolizing bacteria in mixed populations increased > 10,000-fold during enrichment; the rates of nitropropanol metabolism increased 8-fold. Hydrogen and phytone were important nutrients for nitropropanol metabolism.

Complications and salvage of an ectopically replanted thumb

The ectopic replantation of a thumb is described after a mutilating hand injury. The case was followed by a series of complications and surgical procedures to treat these complications. Through perseverance and multiple microsurgical procedures the patient attained a functional hand. The patient's psychological and physical course is described.

A gene-sized DNA molecule encoding heat-shock protein 70 in Oxytricha nova

The gene-sized DNA molecule in the macronucleus (mac) of Oxytricha nova (On) encoding heat-shock protein 70 (Hsp70) was cloned and sequenced. It contains 2654 bp, including telomeres. It consists of a 394-bp A+T-rich 5' leader, a 1956-bp open reading frame (ORF) encoding a putative polypeptide of 651 amino acids (aa), and a 240-bp A+T-rich 3' trailer. The 5' leader contains two copies of the 13-bp heat-shock element (HSE) consensus sequence of other eukaryotes. On responds to heat and CdCl2 stress with a major increase in hsp70 transcripts. The presence of HSE in the nucleotide sequence of hsp70 and the stress-induced in hsp70 transcripts are the first evidence of conventional transcriptional regulation of a hypotrich gene-size DNA molecule. The ORF has large putative ATPase and polypeptide-binding domains with high aa identity to Hsp70 polypeptides of other eukaryotes.

Psychological well-being of the breast reconstruction patient: a pilot study

Though the sample size is small and limited to Caucasian women, the results of this study are promising with respect to a positive adjustment following breast cancer and breast reconstruction. The individuals in this group were functioning very well psychologically. These women were relatively free of anxiety and depression. They employed useful means of coping and held appropriate attributions with respect to their own health. A limitation of the study was the lack of a control group, and the principal investigator is currently conducting another study that employs a control group as well as comparisons with women who have undergone mastectomy without reconstruction and lumpectomy. Continued research regarding psychological well-being of women with breast cancer in general and women who undergo reconstruction specifically is recommended.