Acral mutilation and nociceptive loss in English Pointer dogs

Summary Acral mutilation and analgesia occurred in three of a litter of nine pups produced by a mating of clinically normal English Pointer dogs. Post-mortem studies on one of the affected pups revealed changes at the level of the primary sensory neuron which included: a reduction in spinal ganglia size, a 22–50% deficiency of ganglionic neurons, and a disproportionately large population of small sensory cell bodies. The only change noted in the spinal cord occurred in the dorsolateral fasciculus where reduced fiber density appeared to correlate well with the observed nociceptive defect. Light- and electron-microscopic examination of spinal roots, ganglia, and peripheral nerves provided evidence of myelinated and unmyelinated fiber degeneration. The neuronal degeneration, however, appeared quantitatively inadequate to account for the deficiency of sensory cell bodies. It was concluded that this mutilating acropathy was a manifestation of a sensory neuropathy in which the neuronal deficiency resulted from insufficient development and slowly progressive, postnatal degeneration.The clinical and pathologic findings in this canine disorder were compared with those reported in hereditary sensory neuropathies of man and other animals.This work was supported by NIH grant NS-14242-01, contact RR-9-2102, and Biomedical Research Support Grant funds     

Bone marrow cells from normal and ovariectomized rats respond differently to basic fibroblast growth factor and bone morphogenetic protein 2 treatment in vitro

The protein growth factors basic fibroblast growth factor (bFGF) and bone morphogenetic protein 2 (BMP-2) are being actively pursued for bone tissue engineering. Although both proteins are capable of stimulating osteogenic activity of bone marrow cells (BMCs), no studies have addressed the effect of estrogen deficiency on the growth factor responsiveness of BMCs. This study investigated the osteogenic response of BMCs from normal and ovariectomized (OVX) rats to bFGF and BMP- 2. In the absence of growth factors, a higher number of total colony-forming units (t-CFU) and alkaline phosphatase-expressing CFU (ALP-CFU) were obtained with BMCs derived from OVX rats. The percentage of ALP-CFU, however, was not significantly different between BMCs from the two groups of rats. Whereas BMP-2 did not influence the t-CFU and percentage of ALP-CFU, bFGF decreased t-CFU in BMCs derived from OVX rats and reduced the percentage of ALP-CFU in BMCs from both types of rats. Consistent with the higher t-CFU, the number of mineralized colonies (min-CFU) was also higher for BMCs derived from OVX rats. The number of min-CFU was not influenced by BMP-2 treatment, but was reduced with bFGF treatment. Comparison of the growth factor effects on a per-cell (DNA) basis confirmed the expected stimulatory effect of BMP-2 on ALP activity and mineralization in BMCs from normal rats, but these two parameters were not unequivocally stimulated in BMCs from OVX rats. We conclude that BMCs derived from normal and OVX rats exhibited significant differences in their osteogenic response to bFGF and BMP-2 treatment.     

Protocol-based approach to suspected appendicitis, incorporating the Alvarado score and outpatient antibiotics

BACKGROUND: There is evidence that antibiotics can be used as primary treatment for appendicitis, however, delayed surgical treatment might still be associated with perforation. Most patients at risk of perforation have high Alvarado scores. We designed a protocol-based approach to suspected appendicitis, in which the Alvarado score was used to select patients for early treatment with surgery or outpatient antibiotics. METHODS: Patients included in the present study were adults and children referred to the surgical service at John Hunter Hospital (Newcastle, Australia) with suspected appendicitis in the 12 months from July 2000. Treatment groups: no treatment (Alvarado score 1-4); antibiotics alone (Alvarado 5-7); early surgery (Alvarado 8-10). Outcome measures: time to operation; duration of hospital stay; non-therapeutic operations; delayed treatment in association with perforation; recurrent appendicitis (for those treated with antibiotics). Comparison group: 142 patients managed with 'best clinical practice' as part of an earlier trial. RESULTS: One hundred and twenty-two patients were enrolled. Median time to operation was 3.9 h (comparison group 7.3 h, P = 0.014). Median length of stay was 38.5 h (comparison group 44.2 h, P = 0.041). There were two cases of delayed treatment in association with perforation (2/122 = 1.6%, comparison group 2/142 = 1.4%, P = 0.88) and 10 non-therapeutic operations (10/122 = 8.1%, comparison group 15/142 = 10.6%, P = 0.51). Of those whose initial illness was treated successfully with antibiotics, 2/42 (4.8%) subsequently required appendicectomy. CONCLUSIONS: This protocol-based approach to suspected appendicitis is feasible. A prospective controlled study would be required to confirm potential benefits (in terms of short hospital stay) and to confirm that there is not an increase in adverse outcomes.     

Effects of changing reward on performance of the delayed spatial win-shift radial maze task in pedunculopontine tegmental nucleus lesioned rats

Because it was designed to assess working memory, the delayed spatial win-shift (DSWS) radial maze task has been used to investigate the involvement of corticostriatal structures in executive processing. Excitotoxic lesions of the pedunculopontine tegmental nucleus (PPTg) produce profound deficits in performance of this task that are not accounted for by motor impairment. Thus, PPTg DSWS deficits are hypothesized to support a role for PPTg in complex cognitive processing. However, other studies indicate that the behaviour of PPTg lesioned rats varies depending on level of motivational excitement, assessed by the presence or absence of deprivation, or by manipulations of reward value. Since DSWS performance may also be affected by motivational dysfunction, the present experiment was conducted to examine the effects of post-surgical presentation of a more positive food reward (chocolate drops) on the DSWS retention performance of PPTg lesioned rats. Results confirmed a PPTg lesion deficit: lesioned rats made significantly more errors in both training and test phases, and made errors significantly earlier in their choice sequence in the test phase. Main effects of phase on number of errors indicated that the PPTg test phase deficit was not simply the result of a carry-over impairment from the training phase. PPTg rats receiving chocolate made significantly fewer errors than PPTg rats receiving food pellets. Results suggest that PPTg DSWS deficits are not the result of altered motivation or hedonic appreciation of reward value (or reward change) and therefore support the hypothesis of executive cognitive deficits in PPTg lesioned rats.     

Improving communication among attending physicians, long-term care facilities, residents, and residents' families

Effective bidirectional communication between attending physicians and long-term care facilities is of critical importance to ensure timely, appropriate, and high-quality care that is responsive to residents' needs, values, and preferences. Ongoing communication with residents and residents' families is essential to the establishment of mutual trust and respect. This earned trust and respect in turn promotes frank discussions among long-term care practitioners and the facility staff who can then better guide residents and families through difficult care decisions.     

cGMP-dependent and not cAMP-dependent kinase is required for adenosine-induced dilation of intracerebral arterioles

Adenosine (ADO) is a potent cerebral vasodilator and has been proposed as a metabolic regulator of cerebral blood flow. However, the signal transduction pathway by which ADO causes vasodilation in cerebral microvessels is currently unknown. The current study was designed to investigate the role of cyclic nucleotides and cyclic nucleotide-dependent protein kinases in ADO-induced dilation of resistance-sized rat cerebral arterioles that develop spontaneous tone. Arterioles were cannulated and perfused intraluminally at constant flow (2 microl/min) and pressure (60 mm Hg). ADO (29.7 +/- 2.0%; 1 microM), CGS-21680 (16 +/- 4%, 1 microM), 8-bromo-cyclic guanosine monophosphate (8 Br-cGMP; 29.9 +/- 3.9%; 100 microM), sodium nitroprusside (SNP; 30.6 +/- 3.3%, 1 microM), cyclic guanine monophosphate-dependent protein kinase activator (Sp-8-pCPT-cGMPS, 25.9 +/- 4.2%; 10 microM), forskolin (30.5 +/- 5.9%; 0.1 microM), and pH 6.8 all produced large dilations. The selective cGMP-dependent protein kinase inhibitor, Rp-8-pCPT-cGMPS (10 microM), had no effect on resting diameter or reactivity to acidic pH, but significantly ( < 0.05) attenuated arteriolar dilations to ADO (59%, n = 8), CGS-21680 (60%, n = 4), SNP (62%, n = 3), 8 Br-cGMP (88%, n = 3), and Sp-8-pCPT-cGMPS (98%, n = 3). H8, the less-selective cyclic nucleotide-dependent protein kinase inhibitor, had similar effects as Rp-8-pCPT-cGMPS. Additionally, the inhibitor of the soluble guanylate cyclase, 1H-[1,24]oxadiazolo-[4,3-a]quinoxalin-1-one (ODQ), blocked the response to SNP (70% inhibition) and significantly inhibited the ADO response (43% inhibition). In contrast, inhibition of the cyclic ADO monophosphate (cAMP)-dependent protein kinase Rp-8-CPT-cAMPS had no effect on the ADO, SNP, or pH responses, but significantly blocked forskolin-induced vasodilation (53%). It is concluded that ADO-induced vasodilation in cerebral microvessels, at least in part, involves cGMP and cGMP-dependent protein kinase, but not cAMP or cAMP-dependent kinase. Our data therefore provides a new insight into mechanisms by which ADO invokes vasodilation in cerebral microvascular arterioles.     

Oxidative stress-induced homologous recombination as a novel mechanism for phenytoin-initiated toxicity

Although the mechanism(s) of phenytoin-initiated toxicity is unknown, phenytoin can be enzymatically bioactivated to a reactive intermediate leading to increased formation of reactive oxygen species, which can damage essential macromolecules, including DNA. The oxidation of DNA can induce DNA double-strand breaks (DSBs), which may be repaired through homologous recombination. Increased levels of DSBs may induce hyper-recombination, leading to deleterious genetic changes. We hypothesize that these genetic changes mediate phenytoin-initiated toxicity. To investigate this hypothesis we used a Chinese hamster ovary cell line containing a neo direct repeat recombination substrate to determine whether phenytoin-initiated DNA oxidation increases homologous recombination. Cells were treated with 0 to 800 microM phenytoin for 5 or 24 h, and homologous recombination frequencies and recombinant product structures were determined. Phenytoin-initiated DNA oxidation was determined by measuring the formation of 8-hydroxy-2'-deoxyguanosine. We demonstrate that phenytoin increases both DNA oxidation and homologous recombination in a concentration- and time-dependent manner. All recombination products analyzed arose via gene conversion without associated crossover. Our data demonstrate that phenytoin-initiated DNA damage can induce homologous recombination, which may be a novel mechanism mediating phenytoin-initiated toxicity.