Evaluation of temperature distributions in cadaveric lumbar spine during nucleoplasty

In this study, temperature maps were obtained throughout human cadaveric disc specimens (n = 6) during a simulated Nucleoplasty treatment. The procedure was performed using the Perc-DL SpineWand (ArthroCare, Sunnyvale, CA) inserted through a 17 gage needle into the human cadaveric disc. The device uses a dual mode heating technique which employs a high voltage radio frequency (RF) plasma field to vaporize tissue (Coblation), followed by bipolar RF current heating for thermal coagulation. The device, with a distal 's-curve', is manipulated manually to create a series of six channels at a 60 degrees angular spacing within a period of 3 min. A computer-controlled, motorized translational system was used to reproducibly mimic the insertion (Coblation) and retraction (rf-coagulation) performed during clinical implementation, with rotation performed manually between each Coblation/coagulation cycle. Transient temperature data were obtained using five multi-junction thermocouple probes (5-8 junctions spaced at either 2 or 5 mm intervals, with 0.33 or 0.56 mm probe diameter) spaced throughout the desired heating volume. Transient temperature curves were obtained from 26+ points throughout the disc, and the data used to calculate accumulated thermal doses. Transient peaks of 80-90 degrees C were recorded within the discs, with temperatures greater than 60-65 degrees C measured within a radial distance of 3-4 mm from the introducer (applicator centreline). Accumulated thermal doses of t43 > 250 min were produced at radial distances of up to 6 mm from the introducer. Gross inspection of the discs revealed a narrow region of coagulation along the insertion length. Given these radial thermal penetrations and the possibility for unpredictable positioning during current clinical implementation, high temperatures and lethal thermal doses in small regions outside of the nucleus, or within the bone endplates, may be possible in clinical implementation.     

Diversity of enteric viruses detected in patients with gastroenteritis in a tertiary referral paediatric hospital

The genetic diversity of enteric viruses co-circulating in a cohort of patients with viral gastroenteritis in a large tertiary paediatric hospital in London, UK, was determined. Multiple strains of noroviruses (NV), sapoviruses (SV) and astroviruses (HAsV) were detected in these patients, indicating the likelihood of multiple introductions from different sources, possible sub-clinical infections and simultaneous infection with different viruses in immunocompromised and other patients. Routine screening of immunocompromised patients and infection control procedures are important to prevent nosocomial infection.     

The matrix metalloproteinase-3 (MMP-3) 5A/6A promoter polymorphism is not associated with ischaemic heart disease: analysis employing a family based approach

Matrix metalloproteinase-3 (MMP-3) has been proposed as an important mediator of the atherosclerotic process. The possible role of the functional -1612 5A/6A polymorphism of the MMP-3 gene in the susceptibility to ischaemic heart disease (IHD) was investigated in a well-defined Irish population using two recently described family based tests of association. One thousand and twelve individuals from 386 families with at least one member prematurely affected with IHD were genotyped. Using the combined transmission disequilibrium test (TDT)/sib-TDT and the pedigree disequilibrium test (PDT), no association between the MMP-3 -1612 5A/6A polymorphism and IHD was found. Our data demonstrate that, in an Irish population, the MMP-3 -1612 5A/6A polymorphism is not associated with IHD.     

Failure to produce conditioning with low-dose trimethylthiazoline or cat feces as unconditioned stimuli

Trimethylthiazoline (TMT), a derivative of fox feces, has been reported to fail to produce aversive conditioning as an unconditioned stimulus (UCS) when presented in large amounts (I. S. McGregor, L. Schrama, P. Ambermoon, & R. A. Dielenberg, 2002). Experiment I evaluated very low TMT levels that nonetheless produced defensive behaviors in rats during exposure. Although each level (0.01, 0.05, and 0.10 microl TMT) produced significant change in defensiveness, none resulted in significant changes the following day in the absence of TMT. Experiment 2 evaluated cat urine, cat feces, and cat fur/skin odor against a no-odor control. Urine produced no significant changes, but feces and fur/skin odors elicited virtually identical changes in defensive behaviors during exposure. When tested the next day in the absence of odor, the fur/skin odor-exposed group showed significant differences on the same behaviors as during exposure, but the feces-exposed group showed no differences on any measure. Results suggest that lack of conditioning to TMT may relate to the type of predator odor rather than the amount, predator species, or possible lack of odor components in TMT that are present in natural feces. Predator feces may also be less effective as a UCS because they are poorly predictive of the actual presence of the predator, suggesting the need for a reevaluation of UCS functions in aversive conditioning.     

Genetic heterogeneity of small ruminant lentiviruses involves immunodominant epitope of capsid antigen and affects sensitivity of single-strain-based immunoassay

The pol and gag gene fragments of small ruminant lentivirus field isolates collected in the last decade in Italy were amplified, sequenced, and analyzed. Phylogenetic analysis revealed that the majority of ovine isolates form a distinct cluster more similar to caprine lentivirus prototypes than to the visna virus prototype. These findings confirm and extend those reported by Leroux et al. (Arch. Virol., 142:1125-1137, 1997). Moreover, we observed that a variable region of Gag, included in the fragment analyzed, corresponded to one of the three major capsid antigen epitopes, which suggests that the antibody response to this epitope may be type specific. To test this hypothesis, two recombinant peptides, derived from the Icelandic prototype K1514 and this novel genotype, were expressed and used in an enzyme-linked immunosorbent assay to screen a panel of ovine and caprine sera collected from different geographical locations in Italy. Several sera reacted in a type-specific manner, indicating that in a diagnostic setting the combination of at least these two type-specific peptides is necessary to cover a wide range of infections. Additionally, these results support the hypothesis of cross-species transmission based on the phylogenetic analysis described above. This has implications for the control and eradication of small ruminant lentivirus infections.     

Multilineage potential of homozygous stem cells derived from metaphase II oocytes

Human stem cells derived from human fertilized oocytes, fetal primordial germ cells, umbilical cord blood, and adult tissues provide potential cell-based therapies for repair of degenerating or damaged tissues. However, the diversity of major histocompatibility complex (MHC) antigens in the general population and the resultant risk of immune-mediated rejection complicates the allogenic use of established stem cells. We assessed an alternative approach, employing chemical activation of nonfertilized metaphase II oocytes for producing stem cells homozygous for MHC. By using F1 hybrid mice (H-2-B/D), we established stem cell lines homozygous for H-2-B and H-2-D, respectively. The undifferentiated cells retained a normal karyotype, expressed stage-specific embryonic antigen-1 and Oct4, and were positive for alkaline phosphatase and telomerase. Teratomatous growth of these cells displayed the development of a variety of tissue types encompassing all three germ layers. In addition, these cells demonstrated the potential for in vitro differentiation into endoderm, neuronal, and hematopoietic lineages. We also evaluated this homozygous stem cell approach in human tissue. Five unfertilized blastocysts were derived from a total of 25 human oocytes, and cells from one of the five hatched blastocysts proliferated and survived beyond two passages. Our studies demonstrate a plausible "homozygous stem cell" approach for deriving pluripotent stem cells that can overcome the immune-mediated rejection response common in allotransplantation, while decreasing the ethical concerns surrounding human embryonic stem cell research.     

CD4+ T cell-mediated rejection of major histocompatibility complex class I-disparate grafts: A role for alloantibody

Experimental studies of the T cell requirement for rejection of class I major histocompatibility complex (MHC)-disparate grafts have generated controversy over both the autonomy of CD8⁺ T cells and the mechanism whereby CD4⁺ T cells are able to independently mediate rejection. In this study of rejection of RT1A^a class I MHC-disparate rat cardiac and skin allografts by high-responder PVG RT1^u recipients, we show that elimination of CD8⁺ T cells [by anti-CD8 monoclonal antibody (mAb) administration in vivo] fails to prolong graft survival, whereas partial depletion of CD4⁺ T cells (by anti-CD4 mAb treatment) markedly delays rejection of class I-disparate heart grafts, and marginally prolongs survival of skin grafts. Anti-CD4-treated PVG-RT1^u athymic nude rats reconstituted with CD8⁺ T cells failed to reject class I-disparate skin grafts for several weeks and eventual rejection correlated with re-emergence of a small number of donor derived CD4⁺ T cells. Conversely, anti-CD8-treated nude rats reconstituted with CD4⁺ T cells alone rapidly rejected class I-disparate skin grafts. Passive transfer of anti-class I immune serum to anti-CD4-treated euthymic recipients promptly restored their ability to specifically reject a class I-disparate heart graft. Similarly, passive transfer of immune serum to PVG-RT1^u nude rats bearing skin allografts caused destruction of class I-disparate but not third-party grafts. These results demonstrate that CD4⁺ T cells are both necessary and sufficient to cause rejection of class I-disparate heart and skin grafts in this model and that CD4⁺ T cell-dependent alloantibody plays a decisive role in effecting rejection.     

Activation and Sorting of Human White Blood Cells

We demonstrate a novel activation behavior of human leucocyte adhesion under physiological flow conditions in a microfabricated silicon array of channels with length scales similar to those of human capillaries. Vital nuclei stains and cell specific, flourochrome labeled antibodies reveal that the equilibrium distribution of stuck cells in the arrays displays a strong dependence on cell type and nuclear morphology, and there is eventual separation of the two cell types in the array. The distortion of the cells is the same as they experience in vivo and the response of the granulocytes is consistent with a model describing adhesion as a function of the distortion of the cell by its environment; in other words, activated adhesion. We propose that this complex non-random behavior is due to a deformation activated change in the cells relevant to observed in vivo behavior.     

Patients'' experiences of GP consultations for psychological problems: a qualitative study

BACKGROUND: The vast majority of patients with psychological problems are seen solely by their GP, but little is known about patients' perspectives regarding the variety of consultation skills that may be used in routine GP consultations with these patients. AIM: To identify which aspects of GP consultations patients presenting with psychological problems experience as helpful or unhelpful. DESIGN: Qualitative study. SETTING: Nine general practices in north central London. METHOD: Twenty patients, who had discussed psychological problems as a significant part of their index GP consultation, were asked in detail using the tape-assisted recall (TAR) method, about aspects of the consultation they had experienced as helpful or unhelpful. RESULTS: All patients described how the relationship with the GP helped or hindered them in discussing their problems; this was central to their experience of the consultation. An underlying attitude of genuine interest and empathy, within a continuing relationship, was highly valued. Patients also described how the GP helped them make sense of, or resolve their problems, and supported their efforts to change. CONCLUSION: These patient accounts suggest that routine GP consultations for psychological problems can have a powerful impact, at least short-term. The GP role in providing a safe place where patients feel they are listened to and understood should not be underestimated, particularly in the mental health context. Further research is required to investigate the longer-term impact of different GP behaviours on patient health outcomes. The TAR method has potential applications in primary care research and in the training of GPs and other health professionals.