The preoptic area in the hypothalamus is the source of the additional respiratory drive at raised body temperature in anaesthetised rats

In mammals that use the ventilatory system as the principal means of increasing heat loss, raising body temperature causes the adoption of a specialised breathing pattern known as panting and this is mediated by the thermoregulatory system in the preoptic area of the hypothalamus. In these species an additional respiratory drive is also present at raised body temperature, since breathing can reappear at low Pa,CO2 levels, when stimulation of chemoreceptors is minimal. It is not known whether the preoptic area is also the source of this additional drive. Rats do not pant but do possess this additional respiratory drive at raised body temperatures. We have therefore tested whether the preoptic area of the hypothalamus is the source of this additional respiratory drive in rats. Urethane anaesthesia and hyperoxia were used in eleven rats to minimise behavioural and chemical drives to breathe. The presence of the additional respiratory drive was indicated if rhythmic diaphragmatic EMG activity reappeared during hypocapnia (a mean Pa,CO2 level of 21+/-2 mm Hg, n = 11), induced by mechanical ventilation. The additional respiratory drive was absent at normal body temperature (37?C). When the temperature of the whole body was raised using an external source of radiant heat, the additional respiratory drive appeared at 40.6+/-0.5 degrees C (n = 3). In two further rats this drive was induced at normal body temperature by localised warming in the preoptic area of the intact hypothalamus. The additional respiratory drive appeared at similar temperatures to those in control rats in three rats following isolation of the hypothalamus from more rostral areas of the brain. In contrast, the additional respiratory drive failed to appear at these temperatures in three rats after isolating the hypothalamus from the caudal brainstem, by sectioning pathways medial to the medial forebrain bundle. Since the preoptic area is known to contain thermoreceptors and to receive afferents from peripheral thermoreceptors, the results show that this area is also the source of the additional respiratory drive at raised body temperature in anaesthetised rats.     

Novel and recurrent germline LEMD3 mutations causing Buschke–Ollendorff syndrome and osteopoikilosis but not isolated melorheostosis

Mutations in the LEMD3 gene were recently incriminated in Buschke–Ollendorff syndrome (BOS) and osteopoikilosis, with or without melorheostosis. The relationship of this gene with isolated sporadic melorheostosis is less clear. We investigated LEMD3 in a two-generation BOS family showing an extremely variable expression of the disease, in a sporadic patient with skin features of BOS, and in an additional subject with isolated melorheostosis. We identified two different mutations, both resulting in a premature stop codon, in the two cases of BOS. The mutation (c.2564G>A) reported in the familial case is novel, while that observed in the sporadic case (c.1963C>T) has been previously reported in an American woman with osteopoikilosis and melorheostosis who had a family history of isolated osteopoikilosis. The search for mutations in DNA extracted from the peripheral blood, as well as skin and bone biopsies of the patient with melorheostosis failed to identify any pathogenic change. Our results further expand the LEMD3 mutation repertoire, corroborate the extreme interfamilial and intrafamilial clinical variability of LEMD3 mutations, and underline the lack of a clear phenotype–genotype correlation in BOS. The present study supports the general conclusion that LEMD3 mutations do not contribute to isolated sporadic melorheostosis. The genetic or epigenetic influences that are responsible for the development of melorheostosis require further investigation.     

Production and tumour-binding characterization of a chimeric anti-CEA Fab expressed in Eschericwa coli

A recombinant chimeric Fab (rcFab), with Fv derived from the monoclonal A5B7 antibody to carcinoembryonic antigen (CEA), and with human CHI and Ck was cloned into pUC 19 and expressed in Escherichia coli. rcFab (10 to 12 mg per litre) was produced in bacterial culture fluid, and functional purified rcFab was isolated by affinity chromatography (using antibody to human Ck) and size-exclusion gel filtration. The re Fab did not show reduced affinity for CEA, and reacted with human colorec-tal tumours showing a typical anti-CEA pattern by immunocyto-chemistry; it was also stable after iodination. Biodistribution studies in nude mice bearing human tumour xenografts showed no toxicity and good turnout- localization. Therapeutic ratios at early time points were better than those obtained with whole murine antibody. The results demonstrate that bacterial I y produced anti-CEA Fab is of use for tumour targeting. © Wiley-Liss, Inc.     

Altered biodistribution of an antibody--enzyme conjugate modified with polyethylene glycol.

Polyethylene glycol modification of the antibody--enzyme conjugate, F(ab'')2-A5B7-CPG2, extends its duration in the circulation of nude mice bearing human colonic cancer xenografts (LS174T). Increased concentration of modified conjugate is achieved in the tumour, but residual non-specific enzyme concentrations in normal tissue and blood demonstrate the fundamental requirement to remove or inactivate non-specifically held enzyme in this system.     

In situ localization of F-actin in the normal and injured guinea-pig tympanic membrane

Although cell migration is an important function of the epithelial cells of the tympanic membrane (TM), little is known about the distribution of the F-actin cytoskeleton, a contractile protein important in cell motility. The purpose of this experiment was to study the in situ localization of F-actin in the epithelial cells of the TM. F-actin, localized using Rhodamine-phalloidin, was present as a thin cortical band at the margin of both the mucosal cells on the inner side of the drum, and the suprabasal cells of the epidermis. The basal cells showed diffuse circumferential F-actin staining sometimes appearing as short microfilaments. Following a full thickness injury, changes in the distribution of F-actin could be observed with in situ localization. While the diffuse F-actin staining of the basal cells was reduced, both long F-actin microfilament bundles extending parallel to the long axis of the cell and focal aggregates of F-actin were prominent. The suprabasal cells became elongated, and while the F-actin remained localized to the cell margin, faint central F-actin microfilaments were observed. The staining of the mucosal cells remained unchanged. This study showed that the guinea pig TM is a useful model to study the distribution of epithelial F-actin in situ under normal and repair conditions, and that the basal cell layer may be important in regulating migration in the epidermis.     

Using machine learning classifiers to identify glaucomatous change earlier in standard visual fields

PURPOSE: To compare the ability of several machine learning classifiers to predict development of abnormal fields at follow-up in ocular hypertensive (OHT) eyes that had normal visual fields in baseline examination. METHODS: The visual fields of 114 eyes of 114 patients with OHT with four or more visual field tests with standard automated perimetry over three or more years and for whom stereophotographs were available were assessed. The mean (+/-SD) number of visual field tests was 7.89 +/- 3.04. The mean number of years covered (+/-SD) was 5.92 +/- 2.34 (range, 2.81-11.77). Fields were classified as normal or abnormal based on Statpac-like methods (Humphrey Instruments, Dublin, CA) and by several machine learning classifiers. The machine learning classifiers were two types of support vector machine (SVM), a mixture of Gaussian (MoG) classifier, a constrained MoG, and a mixture of generalized Gaussian (MGG). Specificity was set to 96% for all classifiers, using data from 94 normal eyes evaluated longitudinally. Specificity cutoffs required confirmation of abnormality. RESULTS: Thirty-two percent (36/114) of the eyes converted to abnormal fields during follow-up based on the Statpac-like methods. All 36 were identified by at least one machine classifier. In nearly all cases, the machine learning classifiers predicted the confirmed abnormality, on average, 3.92 +/- 0.55 years earlier than traditional Statpac-like methods. CONCLUSIONS: Machine learning classifiers can learn complex patterns and trends in data and adapt to create a decision surface without the constraints imposed by statistical classifiers. This adaptation allowed the machine learning classifiers to identify abnormality in visual field converts much earlier than the traditional methods.     

Osteoinductive molecules in orthopaedics: basic science and preclinical studies

Osteoinductive molecules are characterized by their ability to promote the formation of bone. Most osteoinductive molecules are cytokines, which are extracellular proteins or peptides that mediate cell to cell signaling. Examples of osteoinductive cytokines are certain bone morphogenetic proteins and some growth and differentiation factors. Some osteoinductive molecules are not secreted molecules. LIM mineralization protein-1 is an example of an intracellular osteoinductive molecule. Significant advances have been made in characterizing the molecular composition and mechanism of action of these osteoinductive molecules. Preclinical studies with these molecules have provided better understanding of the doses, formulation, and delivery mechanism necessary for effective bone formation in model systems of spinal fusion and other orthopaedic problems. The current authors will review the most important basic science and preclinical studies involving these osteoinductive molecules.     

Obesity and diabetes mellitus--how are they linked?

There is a large body of evidence which indicates that elevated plasma levels of FFA are a major cause of insulin resistance in skeletal muscle and liver. Normalizing plasma FFA levels is, therefore, proposed as a novel approach to reduce insulin resistance, the risk of Type 2 diabetes mellitus and atherosclerotic vascular disease.     

The effects of optical blur on motion and texture perception.

PURPOSE: The purpose of this study is to determine how decreased visual acuity affects performance on tasks of motion and texture perception. METHODS: Positive diopter lenses were used to match three subjects at five levels of decimal visual acuity (DVA) ranging from an uncorrected DVA of 1.6 to the lowest DVA of 0.2. Performance thresholds were determined at each acuity level for five different psychophysical tasks. The tasks assessed the perception of motion-defined form, global motion, maximum motion displacement (Dmax), texture-defined form, and global texture. RESULTS: Reducing visual acuity decreased performance on the tasks of motion-defined form identification, texture-defined form identification, and global texture integration. Performance on the Dmax task improved with a reduction in visual acuity. Performance on the global motion task was unaffected by changes in visual acuity. CONCLUSIONS: Visual acuity should be considered when interpreting the results of developmental or clinical studies of motion and texture perception. The only exception to this is global motion perception, at least when DVA is better than 0.2. The effect of blur on tasks of motion and texture perception may reflect the extent to which high spatial frequency information is required for performance on these tasks.