Fcgamma receptor polymorphisms and periodontal status: a prospective follow-up study.

AIMS: The aims of this study were to assess: (i) the distribution of Fcgamma receptor polymorphisms among patients with chronic periodontitis ("cases") and control subjects with no/minimal loss of periodontal tissue support in a Caucasian population; (ii) whether these polymorphisms can serve as severity markers for periodontitis; and (iii) whether they have any bearing on the response to periodontal therapy. METHODS: The study sample consisted of 132 cases and 73 controls of comparable age and gender. Full-mouth periodontal status was assessed. Subgingival plaque (PL) samples and blood samples were obtained and analysed with respect to 19 bacterial species and homologous serum immunoglobulin G titres. Polymorphisms in the Fcgamma receptor IIa (131R/H) and IIIb (NA1/NA2) were assessed by polymerase chain reaction. Patients underwent periodontal therapy and were followed up at 4 and 30 months. RESULTS: Neither polymorphism showed a skewed distribution among cases and controls. At baseline, periodontitis patients with Fcgamma RIIa-H/H131 genotype had more PL and deeper pockets than patients in other genotype groups (p < 0.05). Both bacterial levels and antibody titres were unrelated to genotype. The longitudinal analysis failed to detect an association between genotype and response to periodontal therapy. CONCLUSIONS: The present data failed to demonstrate a clinically relevant relationship between the Fcgamma receptor IIa (131R/H) or IIIb (NA1/NA2) polymorphism and periodontal status.

The props-based interface for neurosurgical visualization.

We describe a three-dimensional human-computer interface for neurosurgical visualization. The interface is based on the two-handed physical manipulation of hand-held tools, or "props", in free space. These user interface "props" facilitate transfer of the user's skills for manipulating tools with two hands to the operation of a user interface for visualizing 3D medical images, without need for training. The interface allows neurosurgeons to explore a 3D MRI scan of a patient's brain during presurgical planning. From the surgeon's perspective, the interface is analogous to holding a miniature head in one hand which can be "sliced open" or "pointed to" using a cross-sectioning plane or a stylus tool, respectively, held in the other hand. Cross-sectioning a 3D volume, for example, simply requires the surgeon to hold a plastic plate (held in the preferred hand) up to the miniature head (held in the nonpreferred hand) to demonstrate the desired cross-section.

Glyceryl trinitrate enhances nitric oxide mediated perfusion within the equine hoof.

Laminitis, a microvascular disease of the equine hoof leads to severe lameness. Exogenous iv 1-arginine and transdermal nitric oxide donors, such as GTN, applied to the pasterns improve lameness during acute laminitis. Near Infrared spectroscopy in an earlier study showed haemostasis and ischaemia in the hoof during acute laminitis, both were alleviated by 1-arginine. Quantitative NIRS in the present study shows that transdermal GTN increases blood flow in the equine hoof. It is concluded that glyceryl trinitrate enhances nitric oxide mediated perfusion within the equine hoof in normal and chronically laminitic horses and ponies.

Nitric oxide donors as treatment for grass induced acute laminitis in ponies.

The potential for participation of the arginine-nitric oxide system in the aetiology of acute equine laminitis has been assessed. Nitric oxide (NO), produced by the action of NO synthase (NOS) on its substrate l-arginine, relaxes vascular smooth muscle to cause vasodilation. An attenuated normal vasodilatory tone may characterise the pathogenesis of acute equine laminitis. An intravenous infusion of 10% l-arginine in 0.9% saline caused vasodilatation in the hoof of a normal pony and immediate reperfusion of laminal tissues in an acutely laminitic pony, detected noninvasively by near infrared spectroscopy (NIRS), but the amino acid had little effect on systemic blood pressure. Treatment of acute laminitis with glyceryl trinitrate applied topically to the pasterns reduced the typical 'bounding pulses' in treated limbs, reduced lameness and lowered systemic blood pressure. Nitric oxide is likely to participate in the multifactorial pathogenesis of equine laminitis.

Near infrared spectroscopy of pedal haemodynamics and oxygenation in normal and laminitic horses.

The present study applies near infrared spectroscopy (NIRS) to the haemodynamics of the pedal circulation in normal and laminitic horses. NIRS is a noninvasive technique which uses changes in light absorption at 4 wavelengths to provide information on the changes in cytochrome aa3 (cyt aa3) reduction-oxidation (redox) status, and changes in the tissue concentration of oxyhaemoglobin (O2Hb), deoxyhaemoglobin (HHb) and therefore total haemoglobin (tHb). Other studies have shown NIRS to be sensitive to changes in tissue oxygenation and perfusion in human cerebral and limb circulation. In this study, the NIRS sensor was applied to the dorsal surface of horses' hooves. Normal and laminitic animals (acute and chronic) were subjected to manoeuvres (cuff tourniquet; digital vessel occlusion at the palmar surface of the pastern; lifting of contralateral limb) predicted to change pedal haemodynamics. The procedures produced changes in pedal haemodynamics and oxygenation, which were similar to those observed in the ischaemic/reperfused human forearm. Laminitic differed from normal horses: return of HHb to baseline was slower and the change in cyt aa3 more rapid than normal in cases of chronic laminitis, taken to indicate reduced O2 stores as a result of compromised basal perfusion. In acute laminitis, baseline values did not fluctuate following any of the manoeuvres, suggesting haemostasis in the diseased hoof. NIRS is a useful noninvasive method to assess pedal vascular function in normal and laminitic horses.

The changing national policy system: complexity, Medicare, and implications for aging groups.

Changes in congressional processes, health agendas, and competitive positions of physician and hospital groups in the 1980s have produced important setbacks for such group interests within Medicare. Though united and successful in opposing Carter's 1977-79 hospital cost-containment proposals, these groups were subjected to severe new limits on hospital reimbursements under the 1982 budget reconciliation act. Thereafter, problems in protecting their interests continued or increased. Disagreements among hospital groups (e.g., the American Hospital Association and the former Federation of American Hospitals) surfaced over the Prospective Payment System introduced in 1983. In 1984, Congress instituted a freeze on physicians' Medicare fees despite AMA opposition. This projected narrow self-interest, thus decreasing the AMA's credibility. Further cost restrictions were imposed in 1985-86 budget acts. The problems of these organizations indicate that if aging groups are to protect their own stake in Medicare in the new political context, they must be particularly concerned with unity, credibility, and long-term perspectives.