The effect of estrogen on brown adipose tissue activity in male rats

Objective

Centrally administered estrogen can increase sympathetic nerve activity to brown adipose tissue, resulting in thermogenesis. The central thermogenic effects of estrogen have not been investigated in males. Therefore, this study sought to investigate the effects of peripherally and centrally administered estrogen on thermogenesis, heart rate and mean arterial pressure in male rats. Thermogenesis was assessed by monitoring brown adipose tissue temperature.

Results

Peripherally administered estrogen elicited no significant effect on brown adipose tissue temperature, heart rate or mean arterial pressure. Centrally administered estrogen elicited a coincident increase in both brown adipose tissue and core temperature. Centrally administered estrogen also resulted in a decrease in mean arterial pressure but had no effect on heart rate. With the present data it is not possible to elucidate whether changes in temperature were the result of thermogenic or thermoregulatory mechanisms.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13104-022-05910-x.

Validation of Three Rapid Screening Methods for Detection of Verotoxin-Producing Escherichia coli in Foods: Interlaboratory Study

An interlaboratory study was conducted for the validation of 3 methods for the detection of all verotoxin-producing Escherichia coli (VTEC) in foods. The methods were a multi-analyte 1-step lateral flow immunoassay (LFIA) for detection of E. coli O157 and verotoxin (VT); an enzyme-linked immunosorbent assay targeted against VT1, VT2, and VT2c (VT-ELISA); and a polymerase chain reaction (PCR) method for detection of VT genes (VT-PCR). Aliquots (25 g or 25 mL) of 4 food types (raw minced [ground] beef, unpasteurized milk, unpasteurized apple juice [cider], and salami) were individually inoculated with low numbers (<9 to 375 cells/25 g) of 6 test strains of E. coli (serogroups O26, O103, O111, O145, and O157) with differing VT-producing capabilities. Five replicates for each test strain and 5 uninoculated samples were prepared for each food type. Fourteen participating laboratories analyzed samples using the LFIA, 9 analyzed the samples by ELISA, and 9 by PCR. The LFIA for O157 and VT had a specificity (correct identification of negative samples) of 92 and 94%, respectively, and a sensitivity (correct identification of positive samples) of 94 and 55%, respectively. The VT-ELISA and VT-PCR

Hip abductor muscle volume in hip osteoarthritis and matched controls

OBJECTIVE

Hip abductor muscle strength and function is negatively impacted by the presence of hip osteoarthritis (OA). This study aimed to quantify differences in hip abductor muscle volume, fatty infiltration and strength in a unilateral hip OA population when compared to a control group. Impact of radiographic severity of OA on these variables was also examined.

METHODS

Volumes of gluteus maximus (GMax), medius (GMed) minimus (GMin) and tensor fascia lata (TFL) was measured using MRI and muscle volume asymmetry between limbs was calculated. Fatty infiltrate within muscles was graded using the Goutallier classification system. Hip abduction and rotation strength was tested using a dynamometer. Differences between groups or limbs were analysed using t-tests and differences in fatty infiltration using non-parametric tests.

RESULTS

A statistically significant decrease in muscle volume was identified in GMax (P < 0.01), GMed (P < 0.02) and GMin (P < 0.01) on the affected side in the OA group compared to both the contralateral side and the control group and differences were related to severity of OA. Hip abduction and internal rotation strength was reduced in the OA group. Increased levels of fatty infiltration were identified in the affected limbs of the OA group for GMax (P = 0.01) and GMin (P = 0.04).

CONCLUSION

Gluteal muscle atrophy, increased gluteal fatty infiltration and hip strength deficits were evident in the affected hips of OA participants. Since severity of OA was related to the extent of atrophy and fatty deposits, rehabilitation programs targeting these muscles could reverse or halt the progression of these structural and functional deficits.

A critical review of cell culture strategies for modelling intracortical brain implant material reactions

The capacity to predict in vivo responses to medical devices in humans currently relies greatly on implantation in animal models. Researchers have been striving to develop in vitro techniques that can overcome the limitations associated with in vivo approaches. This review focuses on a critical analysis of the major in vitro strategies being utilized in laboratories around the world to improve understanding of the biological performance of intracortical, brain-implanted microdevices. Of particular interest to the current review are in vitro models for studying cell responses to penetrating intracortical devices and their materials, such as electrode arrays used for brain computer interface (BCI) and deep brain stimulation electrode probes implanted through the cortex. A background on the neural interface challenge is presented, followed by discussion of relevant in vitro culture strategies and their advantages and disadvantages. Future development of 2D culture models that exhibit developmental changes capable of mimicking normal, postnatal development will form the basis for more complex accurate predictive models in the future. Although not within the scope of this review, innovations in 3D scaffold technologies and microfluidic constructs will further improve the utility of in vitro approaches.

Small bioactive molecules as dual functional co-dopants for conducting polymers

Scanning electron microscope image of surface morphology of conducting polymer PEDOT doped with bioactive molecules.

Laser patterning of platinum electrodes for safe neurostimulation

OBJECTIVE

Laser surface modification of platinum (Pt) electrodes was investigated for use in neuroprosthetics. Surface modification was applied to increase the surface area of the electrode and improve its ability to transfer charge within safe electrochemical stimulation limits.

APPROACH

Electrode arrays were laser micromachined to produce Pt electrodes with smooth surfaces, which were then modified with four laser patterning techniques to produce surface structures which were nanosecond patterned, square profile, triangular profile and roughened on the micron scale through structured laser interference patterning (SLIP). Improvements in charge transfer were shown through electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and biphasic stimulation at clinically relevant levels. A new method was investigated and validated which enabled the assessment of in vivo electrochemically safe charge injection limits.

MAIN RESULTS

All of the modified surfaces provided electrical advantage over the smooth Pt. The SLIP surface provided the greatest benefit both in vitro and in vivo, and this surface was the only type which had injection limits above the threshold for neural stimulation, at a level shown to produce a response in the feline visual cortex when using an electrode array implanted in the suprachoroidal space of the eye. This surface was found to be stable when stimulated with more than 150 million clinically relevant pulses in physiological saline.

SIGNIFICANCE

Critical to the assessment of implant devices is accurate determination of safe usage limits in an in vivo environment. Laser patterning, in particular SLIP, is a superior technique for improving the performance of implant electrodes without altering the interfacial electrode chemistry through coating. Future work will require chronic in vivo assessment of these electrode patterns.

Performance of conducting polymer electrodes for stimulating neuroprosthetics

OBJECTIVE

Recent interest in the use of conducting polymers (CPs) for neural stimulation electrodes has been growing; however, concerns remain regarding the stability of coatings under stimulation conditions. These studies examine the factors of the CP and implant environment that affect coating stability. The CP poly(ethylene dioxythiophene) (PEDOT) is examined in comparison to platinum (Pt), to demonstrate the potential performance of these coatings in neuroprosthetic applications.

APPROACH

PEDOT is coated on Pt microelectrode arrays and assessed in vitro for charge injection limit and long-term stability under stimulation in biologically relevant electrolytes. Physical and electrical stability of coatings following ethylene oxide (ETO) sterilization is established and efficacy of PEDOT as a visual prosthesis bioelectrode is assessed in the feline model.

MAIN RESULTS

It was demonstrated that PEDOT reduced the potential excursion at a Pt electrode interface by 72% in biologically relevant solutions. The charge injection limit of PEDOT for material stability was found to be on average 30× larger than Pt when tested in physiological saline and 20× larger than Pt when tested in protein supplemented media. Additionally stability of the coating was confirmed electrically and morphologically following ETO processing. It was demonstrated that PEDOT-coated electrodes had lower potential excursions in vivo and electrically evoked potentials (EEPs) could be detected within the visual cortex.

SIGNIFICANCE

These studies demonstrate that PEDOT can be produced as a stable electrode coating which can be sterilized and perform effectively and safely in neuroprosthetic applications. Furthermore these findings address the necessity for characterizing in vitro properties of electrodes in biologically relevant milieu which mimic the in vivo environment more closely.

The stabilizing role of the rotator cuff at the shoulder--responses to external perturbations

BACKGROUND

The rotator cuff has been hypothesized as a dynamic stabilizer at the shoulder joint yet evidence supporting this role remains inconclusive. We aimed to investigate the activity levels and recruitment patterns between the rotator cuff and superficial shoulder muscles in response to external perturbations to provide insight into the stabilizing role of the rotator cuff.

METHODS

Surface and intramuscular electromyography (EMG) were used to measure timing of onset and level of activation (EMG amplitude as a percentage of maximum voluntary isometric contraction, % MVIC) of rotator cuff (supraspinatus, infraspinatus and subscapularis) and superficial muscles (anterior and posterior deltoid) on 19 healthy participants. Participants received expected and unexpected externally applied perturbations in directions of internal and external rotation at the glenohumeral joint.

FINDINGS

All three rotator cuff muscles demonstrated pre-activation in anticipation of the perturbation prior to their representative global synergists, anterior and posterior deltoid (P<0.05). Subscapularis and infraspinatus were activated prior to all other muscles during external rotation and internal rotation perturbation trials respectively (P<0.01). Direction specific activation levels were observed; subscapularis was moderately strongly active (37% MVIC) in response to an external rotation perturbation and infraspinatus was moderately active (28% MVIC) in response to an internal rotation perturbation. No muscle was activated >10% MVIC when not acting as the main muscle opposing the movement.

INTERPRETATION

The rotator cuff may function in part as a dynamic stabilizing unit of the shoulder demonstrating a feedforward muscle activation pattern. These results may assist in improving assessment and treatment of shoulder dysfunction.

Conducting polymer electrodes for visual prostheses

Conducting polymers (CPs) have the potential to provide superior neural interfaces to conventional metal electrodes by introducing more efficient charge transfer across the same geometric area. In this study the conducting polymer poly(ethylene dioxythiophene) (PEDOT) was coated on platinum (Pt) microelectrode arrays. The in vitro electrical characteristics were assessed during biphasic stimulation regimes applied between electrode pairs. It was demonstrated that PEDOT could reduce the potential excursion at a Pt electrode interface by an order of magnitude. The charge injection limit of PEDOT was found to be 15 x larger than Pt. Additionally, PEDOT coated electrodes were acutely implanted in the suprachoroidal space of a cat retina. It was demonstrated that PEDOT coated electrodes also had lower potential excursions in vivo and electrically evoked potentials (EEPs) could be detected within the vision cortex.

Novel neural interface for implant electrodes: improving electroactivity of polypyrrole through MWNT incorporation

Multi-walled carbon nanotubes (MWNTs) can be incorporated into conductive polymers to produce superior materials for neural interfaces with high interfacial areas, conductivity and electrochemical stability. This paper explores the addition of MWNTs to polypyrrole (PPy) through two methods, layering and codeposition. Conductivity of PPy doped with polystyrene sulfonate (PSS), a commonly used dopant, was improved by 50% when MWNTs were layered with PPy/PSS. The film electrochemical stability was improved from 38% activity to 66% activity after 400 cycles of oxidation and reduction. Growth inhibition assays indicated that MWNTs are not growth inhibitory. The electroactive polymer-MWNT composites produced demonstrate properties that suggest they are promising candidates for biomedical electrode coatings.

Dredged Illinois River sediments: plant growth and metal uptake

Sedimentation of the Illinois River in central Illinois has greatly diminished the utility and ecological value of the Peoria Lakes reach of the river. Consequently, a large dredging project has been proposed to improve its wildlife habitat and recreation potential, but disposal of the dredged sediment presents a challenge. Land placement is an attractive option. Previous work in Illinois has demonstrated that sediments are potentially capable of supporting agronomic crops due to their high natural fertility and water holding capacity. However, Illinois River sediments have elevated levels of heavy metals, which may be important if they are used as garden or agricultural soil. A greenhouse experiment was conducted to determine if these sediments could serve as a plant growth medium. A secondary objective was to determine if plants grown on sediments accumulated significant heavy metal concentrations. Our results indicated that lettuce (Lactuca sativa L.), barley (Hordeum vulgare L.), radish (Raphanus sativus L.), tomato (Lycopersicon lycopersicum L.), and snap bean (Phaseolus vulagaris L. var. humillis) grown in sediment and a reference topsoil did not show significant or consistent differences in germination or yields. In addition, there was not a consistent statistically significant difference in metal content among tomatoes grown in sediments, topsoil, or grown locally in gardens. In the other plants grown on sediments, while Cd and Cu in all cases and As in lettuce and snap bean were elevated, levels were below those considered excessive. Results indicate that properly managed, these relatively uncontaminated calcareous sediments can make productive soils and that metal uptake of plants grown in these sediments is generally not a concern.

A pilot study using magnetic resonance imaging to determine the pattern of muscle group recruitment by rowers with different levels of experience

OBJECTIVE

To determine whether it was possible using magnetic resonance imaging (MRI) to define the pattern of muscle recruitment in a specific sport (rowing) and to see whether there were differences in this pattern between athletes of different experience.

DESIGN AND METHOD

It has been shown that during vigorous exercise the water content of muscle increases transiently. This can be observed using MRI, where the prolonged T2 relaxation time of muscle can be demonstrated. In this study we have exploited the increase in signal seen in exercised muscle on short TI inversion recovery (STIR) sequences, to show how rowers of different experience use different muscle groups.

RESULTS

We have shown that trained athletes recruit selected muscle groups to carry out a given task, which they carry out more efficiently than untrained or less experienced athletes.

CONCLUSION

We have provided the basis of potential research to refine training methods, in order to develop specific muscle groups in athletes, in the hope of achieving a higher level of performance at an earlier stage in their training. We have also defined a technique that may be of clinical value in cases of muscle dysfunction.

Familial pulmonary hypoplasia: plain film appearances with histopathological correlation

Familial pulmonary hypoplasia is a rare cause of bilateral pulmonary hypoplasia. We describe the plain film appearances and correlate these with the histopathological findings in an infant who survived 5 weeks. In this case, improved technology prolonged survival, allowing the radiological appearance of the primitive lung architecture to become more clearly defined.

Clotting times and antithrombin III activity in cats with naturally developing diseases: 85 cases (1984-1994)

OBJECTIVE

To determine the prevalence of abnormalities of in vitro prothrombin time (PT) and activated partial thromboplastin time (APTT), or antithrombin III (ATIII) activity or all 3 variables in cats; and the association of abnormalities of these variables with naturally developing diseases or disorders.

DESIGN

Retrospective study.

ANIMALS

85 cats from which blood had been obtained for measurement of a coagulation profile (PT, APTT, and ATIII activity) and concentration of fibrin degradation products.

PROCEDURE

Medical records from the Texas A&M College of Veterinary Medicine were reviewed to determine clinical diagnosis, results of CBC and coagulation profile, and clinical evidence of abnormal bleeding or thrombotic disease.

RESULTS

38 cats had one or more abnormality in the coagulation profile; most had multiple abnormalities. Twenty of these 38 cats had concurrent thrombocytopenia. Thrombocytopenia was identified in 9 of 47 cats in which results of the coagulation profile were normal. Most cats did not have clinical evidence of a coagulation disorder, and testing had been requested as part of a diagnostic work-up or before surgery. Diseases commonly associated with laboratory evidence of a coagulation disorder, either singly or in combination, included hepatic disease, neoplasia, and systemic infections.

CLINICAL IMPLICATIONS

On the basis of laboratory evidence, hemostatic disorders develop more commonly in cats than clinical signs would suggest. Coagulation profiles may be warranted in high-risk cats to alert clinicians to potential problems.

Gastrinoma: a retrospective study of four cases (1985-1995)

Islet-cell tumors of the pancreas, such as gastrinoma, are rare in veterinary medicine. Patients with gastrinoma or Zollinger-Ellison syndrome have elevated serum gastrin levels which ultimately cause gastrointestinal ulcerations. Due to their small size, gastrinomas are a challenge to localize prior to surgery. In veterinary medicine, exploratory surgery with biopsy for histopathology confirms the diagnosis of gastrinoma. This is a retrospective study of four dogs with gastrinoma.

Splenic vein thrombosis resulting in acute anemia: an unusual manifestation of nephrotic syndrome in a Chinese shar pei with reactive amyloidosis

Nephrotic syndrome in a seven-year-old Chinese shar pei resulted in oliguric renal failure, coagulopathy, and acute anemia. Renal amyloidosis and widespread thromboses were diagnosed postmortem. Splenic vein thrombosis caused significant splenic congestion, coagulative necrosis, and acute anemia. Splenic vein thrombosis is reported here as an unusual consequence of nephrotic syndrome in the dog.

Platelet function defect in a 5-day-old Simmental calf

A 5-day-old Simmental Heifer was evaluated for excessive bleeding from the skin following horse fly bites. A coagulation profile and platelet numbers were normal. In vitro platelet function, measured by whole blood aggregometry, was found to be abnormal when compared with age-matched controls. Therefore, this defect in hemostasis was attributed to a qualitative defect in platelet function.

Antipyrine and caffeine dispositions in clinically normal dogs and dogs with progressive liver disease

Dispositions of caffeine and antipyrine were compared as indicators of decreasing hepatic function in dogs with experimentally induced progressive liver disease. Dimethylnitrosamine, a hepatospecific toxin, was administered orally to 16 dogs; 6 dogs served as controls (group 1). Three classes of liver disease were defined by histologic features: mild (group 2; n = 5), moderate (group 3; n = 6), and severe (group 4; n = 5). Disposition of antipyrine, and 24 hours later, caffeine was studied 3 weeks after the last dose of toxin in each dog. For both drugs, rapid IV administration of 20 mg/kg of body weight was administered and serum samples were obtained at intervals for determination of at least 5 terminal-phase drug half-lives. For both drugs, clearance and mean residence time differed among groups (P < or = 0.01). Clearance of antipyrine and caffeine was decreased in groups 3 and 4, compared with groups 1 and 2. Antipyrine and caffeine mean residence times were longer in group-3 dogs, compared with dogs of groups 1 and 2. Correction of caffeine and antipyrine clearances for hepatic weight increased discrimination between groups 3 and 4. The clearance and mean residence time ratios of antipyrine to caffeine were calculated for each group and, when compared with values for group-1 dogs, were used to test for differences between the 2 drugs in response to disease. Ratios did not differ among groups. These results indicate that the disposition of antipyrine and caffeine may change similarly with progression of dimethylnitrosamine-induced liver disease.

Effects of single-dose L-asparaginase on coagulation values in healthy dogs and dogs with lymphoma

Ten healthy dogs and 10 dogs with multicentric lymphoma were given a single dose of L-asparaginase at a rate of 10,000 IU/m2 of body surface. Assessment of concentrations of contributors to the coagulation process and of the ability to coagulate including antithrombin III, one-stage prothrombin time, prothrombin-proconvertin time, activated partial thromboplastin time, plasminogen, fibrinogen, and platelet number were performed prior to drug administration (day 0). These tests were repeated 24 hours (day 1), 48 hours (day 2), and 7 days after treatment with L-asparaginase. Antithrombin-III concentrations were significantly lower in the dogs with lymphoma than in healthy dogs on days 0, 1, 2, and 7; however, with the exception of day 1, mean values remained within normal limits. There was also a difference between the 2 groups in prothrombin/proconvertin values on day 7 and in platelet number on day 2, with the lymphoma group having significantly shorter prothrombin/proconvertin time than healthy dogs, and the difference in platelet numbers being associated with increased counts in the healthy dogs. Data obtained from the healthy dogs and dogs with lymphoma for each coagulation test were pooled for each treatment day (0, 1, 2, and 7), and day-0 values for each coagulation test were compared with data obtained on days 1, 2, and 7. Antithrombin-III concentration on day 7 was significantly lower than on day 0, prothrombin/proconvertin time on day 1 was significantly longer than on day 0, and fibrinogen concentrations on days 1 and 2 were significantly lower than on day 0.(ABSTRACT TRUNCATED AT 250 WORDS)

Indocyanine green disposition in healthy dogs and dogs with mild, moderate, or severe dimethylnitrosamine-induced hepatic disease

Disposition kinetics of indocyanine green (ICG) were used to evaluate hepatic function in healthy Beagles (group 1; n = 6) and Beagles with progressive hepatic disease induced by oral administration of dimethylnitrosamine, a hepatospecific toxin. Three classes of hepatic disease were defined by histologic features: mild (group 2; n = 5), moderate (group 3; n = 6), and severe (group 4; n = 5). Disposition of ICG was studied 3 weeks following the last dose of toxin. A rapid IV injection of 0.5 mg of ICG/kg was administered and serum samples were obtained at certain intervals during 60-minute periods. Serum ICG was analyzed by use of visible spectrophotometry. Disposition kinetics were determined from serum ICG concentrations vs 15- and 60-minute time curves and compared between one another and among groups. Data based on 60-minute time curves were not significantly different from those based on 15-minute curves. Area under the curve for ICG was greatest in group 3. Clearance of ICG was decreased and mean resident time was increased in groups 3 and 4, compared with those in groups 1 and 2. When disposition data (60 minutes) were normalized for differences in hepatic weight among dogs, group-3 mean resident time was significantly greater than that of group 4. This study supports the diagnostic benefits of using ICG disposition kinetics as a method of evaluating hepatic function in dogs with progressive liver disease.

Dimethylnitrosamine-induced hepatotoxicosis in dogs as a model of progressive canine hepatic disease

A model of toxin-induced progressive hepatitis is described in Beagles. The toxin, dimethylnitrosamine, was administered orally to 18 Beagles; 6 dogs comprised a control group. Clinical signs and laboratory test results were monitored as disease progressed and were used to determine the end point of disease. Following euthanasia, histologic lesions were scored and used to derive a total severity score for each dog. Severity scores were then used to allot the 18 dogs to 3 groups of hepatic disease, defined as mild, moderate, or severe. Changes in clinical laboratory test results, including tests of hepatic function, and clinical signs indicative of liver disease were described chronologically for all dogs. Group means of clinical laboratory test results and quantifiable clinical signs (eg, weight loss and ascitic fluid accumulation) were compared. This model offers several advantages, compared with other experimental models of canine hepatic disease. These include hepatospecificity, similarity to natural disease (eg, the development of multiple extrahepatic portosystemic shunts), and the ability to titrate the disease to a desired end point. The major disadvantages of this model were the toxic nature of the drug to human beings and the variation in individual animal response to the toxin, which precludes preassignment of animals into groups.

Coagulopathic effects and therapy of brodifacoum toxicosis in dogs

The clinical signs and laboratory changes of brodifacoum (BDF) intoxicated dogs and their response to vitamin K1 treatment were examined. Brodifacoum, a second-generation anticoagulant rodenticide, was fed to four dogs for 3 consecutive days producing a cumulative dose of 1.1 mg BDF/kg body weight. Clinical observations of the animals were made daily throughout the study. Monitored laboratory parameters included: one-stage prothrombin time (OSPT), activated partial thromboplastin time (APTT), activated coagulation time (ACT), complete blood counts, thrombocyte counts, and serum chemistry values. Response to vitamin K1 therapy was evaluated clinically and by laboratory tests. Serum BDF concentrations were monitored. Inappetence and hemorrhagic tendencies were exhibited by day 5 postrodenticide exposure. One-stage prothrombin time, APTT, and ACT were 25% greater than time zero values at 24, 24, and 72 hours postdosing, respectively. All laboratory parameters returned to normal within 48 hours of initiating vitamin K1 therapy (0.83 mg/kg orally, TID for 5 days). Serum brodifacoum concentrations were highest (1065-1215 ng/mL) during the 3 days after BDF dosing and were detectable (3.0-7.5 ng/mL) until day 24 postexposure. A mean BDF elimination half-life of 6 +/- 4 days was observed.

Factors related to working posture and its assessment among keyboard operators

Video analysis of 15 keyboard operators was conducted over two four-hour periods to determine the effects of symptoms of over-use injury, the adjustability of the workstation, the type of keyboard, time of day and sex on working posture. The only factor which significantly affected posture was the type of keyboard, with operators at typewriters adopting a more extended shoulder position, reduced elbow flexion and increased wrist flexion, than those working at a VDU terminal. Analysis of the components of variance associated with repeated observations revealed that to minimise the variance associated with recording the posture of these subjects, and therefore obtain a representative mean posture, required at least nine observations for wrist angle, four for elbow angle, six for shoulder angle and three for trunk incline. The mean posture adopted by this group of operators was similar to the 'right angles' posture, with the trunk reclined 4 degrees , shoulder extended 1 degrees , elbow 92 degrees and wrist extended 7 degrees .

Microcomputer video image processing technology in working posture analysis: application to seated postures of keyboard operators

A new two-dimensional video-based technique for the recording and analysis of working posture has been developed and applied to seated work. After initial set-up of the portable equipment in the workplace, and attachment of small adhesive retroreflective joint markers on the subject, an operator is not required for the remainder of the recording session. Analysis of the video recording is conducted in the laboratory using custom-written software and a commercially available image-processing package running on an IBM AT-compatible computer. After interactive set-up of a reference frame, the system is able to analyse the full video tape automatically, extracting video frames for analysis at approximately 30-s intervals. Poor image quality may occasionally necessitate interactive analysis. The system is capable of determining postural angles to an accuracy of 1-2 degrees , and thus represents a substantial improvement on other postural analysis systems which are able to be used readily in the workplace.

The correlation of subcarinal density visualized on plain chest roentgenograms with computed tomographic scans

A prospective evaluation of 212 paired chest roentgenograms and computed tomographic (CT) scans was performed to determine the predictive value of detecting subcarinal adenopathy by finding increased subcarinal density on routine roentgenograms. Based on CT criteria for subcarinal lymphadenopathy, 37 true-positive and 124 true-negative cases of subcarinal adenopathy were found in 161 patients. Evaluation of density in the subcarinal area on the routine posteroanterior (PA) chest roentgenograms in these patients demonstrated a sensitivity of 72 percent and specificity of 96 percent for the detection of adenopathy when compared with established CT criteria. False-positive and false-negative appraisals of central mediastinal density on routine roentgenograms appear to be due to the super-imposition of other masses, bullae, or lack of appropriate roentgenographic contrast. The accuracy of predicting the presence or absence of subcarinal adenopathy from routine chest roentgenograms suggests that this observation is clinically useful and should be routinely evaluated.

Anthropometric dimensions and overuse injury among Australian keyboard operators

This study was instigated to examine the relationship between overuse injury and anthropometric dimensions of Australian keyboard operators to investigate the possibility that a poor anthropometric fit of the workstation may result in greater incidence of such disorders. There were no differences between the anthropometric dimensions of sufferers and nonsufferers of overuse injury among the male keyboard operators. Among men in this study, stature and several other anthropometric dimensions as a proportion of stature were similar to those of North American and European populations for which equipment used in Australia is designed. In contrast, among women, significant differences were evident between sufferers and nonsufferers. The sufferers had greater hip widths and seat breadths, and a greater proportion were overweight (body mass greater than 26). There was also a tendency for shorter limb segment lengths among the sufferers. The women as a group, and the sufferers in particular, had several anthropometric dimensions that, as a proportion of stature, were outside the range of reference populations for design of Australian office workstations. The subject numbers in the present study are relatively small; however, they suggest that a proportion of the female population may not be accommodated by equipment currently in use. The increased proportion of sufferers who are overweight may suggest a relationship between overuse injury and lack of exercise, since the latter is well known to cause increased weight. A longitudinal study is needed to confirm this observation.

Effect of overuse injury and the importance of training on the use of adjustable workstations by keyboard operators

The introduction of adjustable workstations for keyboard operators has been widely recommended to eradicate constrained working postures leading to the development of musculoskeletal disorders. A questionnaire evaluating the use of adjustable workstations was analyzed for 514 keyboard operators. Anthropometric dimensions and workstation settings were measured for 15 operators. There was no difference between sufferers and nonsufferers of overuse injury on the basis of adjustability of their equipment. However, sufferers were less satisfied with their equipment and there was evidence that inappropriate postures were being adopted. The availability of adjustable equipment per se does not necessarily solve the problem. The design of the equipment must be based on suitable anthropometric data and operators must be trained in the correct use of the equipment. The results of this study indicate a perceived need for training and/or information on workstation adjustment among operators, with a preference for information that is supplied verbally, rather than in literature form.

The "knot twist": a new method of securing wire loops--an assessment of mechanical properties

A model simulating intraosseous wire fixation was used to assess different methods of securing wire loops. Square knotting, twisting, and a new method, the "knot twist," were assessed. The importance of anchoring the butt ends of twisted wire is emphasized. A new, convenient technique of wire fixation is described.

Mondor's disease in plastic surgery patients

Thrombophlebitis of the chest wall is a benign, self-limiting condition. When it is recognized, the patient can be confidently reassured that spontaneous resolution is expected. The characteristic cutaneous cords are palpable five to seven weeks postoperatively, and they generally resolve within several months without specific therapy. Mondor's disease appears to be related to injury of the subcutaneous chest veins at the initial surgery rather than at reoperation. There is no apparent relationship between Mondor's disease and silicon implants nor between Mondor's disease and capsule contracture. Mondor's disease may be more common then generally believed.

3H-amino acid incorporation into proteins during chronic aflatoxin induced coagulation defects in rabbits

Eighteen New Zealand White rabbits were divided equally into three groups and administered either 0.2 ml dimethyl sulfoxide (DMSO)/day, 0.06 mg/kg/day Aflatoxin B1 (AFB1) in DMSO, or 0.09 mg/kg/day AFB1 in DMSO. Incorporation of 3H-amino acids into total serum protein, fibrinogen and platelet proteins was determined during the intoxication and developing coagulation defect. Ten of 18 rabbits administered AFB1 in DMSO died or developed prolonged coagulation times. There was no significant difference in specific incorporation of 3H-amino acids into total serum protein, fibrinogen or platelet proteins between groups, nor was there a difference in incorporation between rabbits with normal coagulation times and those with prolonged coagulation times. Correlation between plasma fibrinogen concentration and specific incorporation of 3H-amino acid into fibrinogen was not significant. In vivo inhibition of 3H-amino acid incorporation into plasma proteins or platelets could not be demonstrated.

Pathophysiology of antithrombin III deficiency

This article focuses on the pathophysiology of thrombosis in patients with acquired antithrombin III deficiency. Antithrombin III is an important natural inhibitor of the hemostatic mechanism, and a hypercoagulable state is often induced in diseases causing antithrombin III deficiency. Laboratory determination of antithrombin III activity is particularly useful in the clinical evaluation and therapeutic management of patients with disseminated intravascular coagulation, nephrotic syndrome, and severe hepatopathy.

Activity of 3-hydroxy-3-methylglutaryl-coenzyme A reductase does not respond to ubiquinone uptake in cultured cells

The cellular content of ubiquinone was increased approx. 10-fold by incubation of neuroblastoma cells in medium containing exogenous ubiquinone. Under these conditions the activity of 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) reductase, assayed after preincubation of cell homogenates with or without fluoride, was not suppressed. Similar results were obtained with human skin fibroblast cultures to which free ubiquinone or low-density lipoprotein-ubiquinone complex had been added. Consistent with the lack of suppression of HMG-CoA reductase, the rate of incorporation of [1-14C] acetate into ubiquinone was not diminished in cells exposed to exogenous ubiquinone. Measurements of [3H]mevalonolactone incorporation into cellular ubiquinones indicated that exogenous ubiquinone did not affect ubiquinone synthesis at a point in the pathway distal to the formation of mevalonate. The results suggest that cultured mammalian cells lack an end-product 'feedback' mechanism for regulation of HMG-CoA reductase in response to ubiquinone uptake.

Use of hexadimethrine bromide as a heparin-neutralizing agent in canine plasma

Hexadimethrine bromide was evaluated as a heparin-neutralizing agent in a simple modification of the activated partial thromboplastin time test in canine plasma. Addition of various amounts of heparin in vitro to canine plasma indicated that heparin could be neutralized by adding 0.5 micrograms of hexadimethrine bromide 15 s before CaCl2 was added to the reaction mixture of the activated partial thromboplastin time test. In 8 dogs given (subcutaneous injection) 500 USP units of sodium heparin/kg, marked individual variations in clotting time prolongations were observed over the 12-hour period of study. The hexadimethrine bromide modification effectively neutralized the heparin-related clotting time prolongations to values that were not significantly different from base-line (preheparin) activated partial thromboplastin time values. The modification seems to be useful in confirming the presence of heparin and in monitoring heparin therapy in dogs.

Coagulation defects of aflatoxin intoxicated rabbits

Twelve New Zealand white rabbits were intoxicated with aflatoxin B1. Most rabbits developed a coagulation defect near the time of death. Immediately prior to death there were significant decreases in factors V, VII, and VIII coagulant activities and fibrinogen concentration without a change in plasma fibrin(ogen) degradation product concentration, platelet number, and detectable plasma fibrin monomers. Microscopic evidence of disseminated intravascular coagulation was present in one rabbit with marked, diffuse hepatic necrosis. Terminal serum albumin concentration was significantly correlated to plasma factors V and VII activities and fibrinogen concentration. The coagulation defect of aflatoxicosis is primarily due to diminished hepatic synthesis of coagulation factors except when hepatic necrosis is severe enough to initiate intravascular coagulation and consumption of coagulation factors.

Comparison of metrizamide and iohexol for cisternal myelographic examination of dogs

A double-blind study, using metrizamide, iohexol, or Ringer's solution (control) as cisternal myelographic agents, was performed on 25 dogs. Before myelographic examination was done, each dog was subjected to physical, clinical pathologic, and neurologic examinations, as well as examinations by electroencephalography and computerized tomography. These were repeated 24 hours after completion of the myelographic examination. The group of dogs given metrizamide (group II) had a significantly greater occurrence of seizure activity (6 of 10) than did the control dogs (group I; 0 of 5) or dogs given iohexol (group III; 0 of 10; P less than 0.003). In group II, the CSF microprotein concentration was significantly greater 24 hours after myelography was done than were the values in groups I and III (P less than 0.003). Myelograms of the group II dogs (metrizamide) and group III dogs (iohexol) had similar diagnostic qualities. At 24 hours after myelographic examination was done, computerized tomography scan revealed that each dog given metrizamide and iohexol had myelographic contrast material in the brain and cervical spinal cord parenchyma. Seemingly, iohexol has good diagnostic quality, but is less epileptogenic than metrizamide when used in cervical myelographic examinations of dogs.

Systemic pathologic responses in experimental Psoroptes ovis infestation of Hereford calves

Nine Hereford calves were infested with Psoroptes ovis and were allowed to develop clinical mange during a 9-week period. Blood, serum, and urine samples were obtained before and after calves were infested and were compared with those from 3 noninfested control calves. All calves were euthanatized and necropsied 9 weeks after they were infested. Gross and microscopic anatomic changes occurred only in the skin. Calves developed typical exudative dermatitis, the extent of which was dependent on population density of mites. Severely infested calves (50% to 70% of skin with dermatitis) developed a mild anemia and lymphopenia with marked neutropenia and variable eosinophilia. There were also increases in fibrinogen, gamma-globulin, and in vitro lymphocyte response to mitogen stimulation and decreases in anion gap cortisol, albumin, albumin/globulin ratio, and fractional Na clearance values. The severity of many of the changes could be correlated with the extent of dermatitis.

Suppression of murine neuroblastoma growth in vivo by mevinolin, a competitive inhibitor of 3-hydroxy-3-methylglutaryl-coenzyme A reductase

3-Hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase catalyzes the formation of mevalonate, an essential precursor for isoprenoid compounds in mammalian cells. Recent studies have shown that mevinolin, a competitive inhibitor of the reductase, inhibits cell proliferation and induces differentiation in cultured C1300 (Neuro-2A) murine neuroblastoma cells. We now report that mevinolin can inhibit neuroblastoma growth in vivo. The specific activity of HMG-CoA reductase in subcutaneous neuroblastomas increased more than 20-fold between the fifth and eighth days after tumor inoculation, and remained elevated for the remainder of the tumor lifetime in mice. The increase in reductase activity was correlated with a marked increase in tumor DNA content and exponential increase in tumor weight. Using an in vitro assay to monitor the ability of mouse serum to suppress sterol synthesis, we determined that mevinolin was inactivated or cleared from the circulation within 3-6 h after a single subcutaneous injection. However, by using subcutaneous osmotic pumps to deliver a constant infusion of mevinolin, we were able to maintain adequate blood levels of the drug for 7 d. Mevinolin (5 mg/kg per h) suppressed tumor growth (wet weight) significantly when treatment was carried out between day 1 and day 8 or between day 5 and day 12 after tumor inoculation. Histopathological examination of tumors from mevinolin-treated mice revealed few or no mitotic figures and marked cellular degeneration. Measurements of incorporation of (3H)acetate into neuroblastoma sterols and ubiquinones 24 h after implantation of osmotic pumps showed that mevinolin produced a marked inhibition of isoprenoid synthesis in the tumors in vivo. The data suggest that, in addition to their demonstrated utility as cholesterol-lowering drugs, competitive inhibitors of HMG-CoA reductase may have considerable potential as novel antineoplastic agents.

Hypoalbuminemia-related platelet hypersensitivity in two dogs with nephrotic syndrome

Platelet aggregation studies in 2 dogs with nephrotic syndrome disclosed increased platelet sensitivity to a low dose of adenosine diphosphate. Subsequent studies with isolated platelets and plasma indicated that a plasma factor was responsible primarily for inducing platelet hypersensitivity. The increased platelet aggregation response was corrected by increasing the albumin concentration of the plasma. The study suggested an important role for albumin in modulating platelet aggregation and may partially explain the tendency toward thrombosis noted in hypoalbuminemic dogs with nephrotic syndrome.

Results of analyses and bacterial cultures of urine specimens obtained from clinically normal cats by three methods

Six urine specimens were obtained from each of 6 male and 6 female cats in a 3-week period. The first and last specimens from each cat were obtained by cystocentesis, 2 were obtained by urethral catheterization, and 2 were caught during voiding stimulated by manual bladder compression. Quantitative urine cultures did not reveal bacteriuria in specimens obtained by cystocentesis, and urinary tract infection did not develop during the study. Bacteria were found in 3 (25%) of 12 urine specimens obtained by catheterization of males and in 1 (8%) of 12 specimens obtained by catheterization of females. Magnitude of bacteriuria in specimens obtained by catheterization was 10 to 1,000 organisms/ml. Bacteria also were found in specimens obtained during voiding. Each of 11 (100%) cleanly caught specimens obtained from males and 7 (58%) of 12 voided specimens from females contained bacteria. Magnitude of bacteriuria in voided specimens was usually 100 to 10,000 organisms/ml, but 3 voided specimens contained greater than 10,000 organisms/ml. Many bacteriuric specimens contained more than 1 type of organism; however, bacteria that might be suspected of causing urinary tract infections in cats were found frequently. Urinalyses were performed on 66 specimens. Completeness of urinalyses depended on the volume of specimens available, but results were normal except for evidence of hematuria in a few specimens obtained by cystocentesis or catheterization. Hematuria was usually mild and was attributed to hemorrhage caused by minor urinary tract trauma during urine collection.