Vibratory antinociception: effects of vibration amplitude and frequency.

The ability of cutaneous vibration to compromise detection of a nociceptive stimulus was examined in 2 sets of psychophysical experiments. The noxious stimulus was a 10-millisecond burst of radiant heat from a CO(2) laser; at the near-threshold levels used it generally yielded a mild pricking sensation. In both experiments, the detectability (d(e)') of the laser was measured in the presence of different vibratory stimuli and in the absence of vibration. Periods of vibration lasted 10 seconds, bracketing the time of occurrence of the laser. Vibratory and laser stimuli were presented 2.3 cm apart on the dorsal surface of the forearm. Confidence rating procedures yielded receiver operating characteristic curves from which detectability of the laser was calculated. In an amplitude study, vibrations ranging from 10 to 45 dB above threshold were used; results indicated that nociceptive sensitivity gradually declined as vibration amplitude increased. In a frequency study, vibrations ranging from 20 to 230 Hz were used; all interfered with nociception. Combining the results of the 2 studies permitted the conclusion that signals in multiple vibrotactile channels are able to modulate nociception. No one mechanoreceptive channel appears to have a privileged role.     

The effects of hypnosis and of imagery on bleeding time: a brief communication

2 studies are reported, one using hypnotized Ss selected on hypnotizability and one using Ss selected on imagery vividness, whose purpose is to examine whether non-patient Ss can control their bleeding in a laboratory setting. All Ss were cut on both arms with the "Surgicutt" device, an instrument that automatically makes a cut that will bleed from 2 to 10 minutes. Results suggest that Ss, who are instructed to reduce the bleeding time in one arm and to let the other arm bleed normally, are not able to control bleeding time.     

Intracerebral thrombosis. Case report and brief clinical review.

A 29-yr-old writer presented with seizures and left hemiparesis 8 days post-partum. Studies revealed right parietal hemorrhagic infarction secondary to superior sagittal sinus thrombosis. An anticoagulant was given for clot extension associated with increasing cerebral edema and coma. Inpatient rehabilitation was undertaken for residual left hemiparesis, most severe in the leg. Left arm strength rapidly returned to normal. Significant improvement in left leg strength occurred but was delayed for many months. Intracerebral thrombosis is an uncommon but significant cause of stroke in young adults. It frequently occurs in the puerperium and may be associated with unilateral or bilateral neurologic deficits. Treatment with anticoagulants is controversial because of the risk of hemorrhagic cerebral infarction, but may be beneficial in some cases. Recovery may be delayed for several months pending recanalization of the sinus or the development of collateral circulation. The overall prognosis for neurologic and functional recovery in survivors of intracerebral thrombosis is good.     

Temperature effects on free-thyroxine measurements: analytical and clinical consequences.

We compared the analytical and clinical performance of two free-thyroxine (FT4) assays--a solid-phase radioimmunoassay, Spectria, and a time-resolved fluoroimmunoassay, Delfia, both of them two-step methods--with the performance of a direct radioimmunoassay, Nichols, to measure FT4 concentration in equilibrium dialysate of undiluted serum. The three assays showed comparable analytical performance. We tested clinical utility in sera from 135 healthy subjects with and without thyroxine-binding abnormalities and in 61 patients with and without thyroidal illnesses. We found significant differences for FT4 measured by different assays in sera from the same euthyroid patients. To explain the differences, we studied the influence of temperature on performance and calibration. Most important was the neglected fact that the association constant for the binding of thyroxine to thyroxine-binding globulin decreases when the temperature rises from 20 to 37 degrees C, causing a doubling of FT4. The two-step assays, if performed at room temperature without a well-defined calibration, can give misleading FT4 concentrations. This is the case when sera from patients with thyroxine-binding abnormalities are measured against kit standards, made up in normal human sera. If an assay is to reflect the in vivo FT4 concentration at body temperature in all types of samples, it should be performed at body temperature. For practical reasons 37 degrees C is recommended, and reference values should be defined at 37 degrees C. The same might be valid for other free-hormone assays.     

Inhibiting bacteria and skin pH in hemiplegia: effects of washing hands with acidic mineral water.

OBJECTIVE: To evaluate bacterial flora in hemiplegic hands as a possible pathogen of endogenous infection in a rehabilitation unit and to examine the effect of cleansing hands with acidic mineral water on the flora. DESIGN: Case-control study in a university affiliated hospital. Seventy-two patients with hemiplegia caused by cerebrovascular diseases were included in this study. Bacterial flora by the swab method, bacterial frequency on the palm by the stamp method, and skin surface pH were examined before and after single cleansing by immersion in plain or acidic mineral water. RESULTS: The bacterial frequencies of patients with hemiplegia and diabetes were higher than those of normal healthy subjects. After cleansing with acidic mineral water, skin surface pH was decreased and bacterial frequency was markedly decreased. A prolonged decrease in skin surface pH was observed in patients with hemiplegia in contrast to normal healthy subjects who presented a short-term decrease. CONCLUSION: Increased bacterial frequencies were associated with a high skin surface pH caused by disordered skin systems in patients with hemiplegia. Acidic mineral water may be useful for inhibiting bacterial growth in patients with hemiplegia.     

Practice brief: adolescents and HIV clinical trials: ethics, culture, and context.

One quarter of HIV infections globally occur among young people 15 to 24 years of age, and more than half of all new infections are in people younger than 25 years. Clearly, there is a need to identify and implement effective HIV prevention strategies among at-risk teens. Some of the most effective options for slowing the epidemic are biomedical, and several promising methods are in development, including microbicides, vaccines, and preexposure prophylaxis (PREP, or the daily use of antiretrovirals to prevent the acquisition of HIV). There is widespread reluctance to enroll minors in such biomedical prevention trials because of concerns about vulnerability related to physical maturity, experiential maturity, and diminished autonomy as well as legal and social challenges that vary across and within nations. However, excluding minors from trials misses an important opportunity to evaluate the effectiveness, acceptability, and safety of innovative interventions under the best conditions for identifying and resolving potential problems. The challenges of including minors in HIV prevention trials are highlighted through the example of one rural South African community that has been particularly devastated by the HIV epidemic.     

Bench-to-bedside review: a brief history of clinical acid-base

The history of assessing the acid–base equilibrium and associated disorders is intertwined with the evolution of the definition of an acid. In the 1950s clinical chemists combined the Henderson–Hasselbalch equation and the Bronsted–Lowry definition of an acid to produce the current bicarbonate ion-centred approach to metabolic acid–base disorders. Stewart repackaged pre-1950 ideas of acid–base in the late 1970s, including the Van Slyke definition of an acid. Stewart also used laws of physical chemistry to produce a new acid–base approach. This approach, using the strong ion difference (particularly the sodium chloride difference) and the concentration of weak acids (particularly albumin), pushes bicarbonate into a minor role as an acid–base indicator rather than as an important mechanism. The Stewart approach may offer new insights into acid–base disorders and therapies.     

Prolonged maintenance of capsaicin-induced hyperalgesia by brief daily vibration stimuli

This study tests the hypothesis that central sensitization initiated by nociceptive input can be maintained by repeated brief innocuous peripheral inputs. Capsaicin was injected intradermally into the hind paw of adult rats. Three different types of daily cutaneous mechanical stimulations (vibration, soft brush, or pressure) were applied to the capsaicin-injected paw for a period of 2 weeks. Daily stimulation consisted of a 10-s stimulation repeated every 30s for 30 min. Foot withdrawal thresholds to von Frey stimuli applied to the paw were measured once a day for 4 weeks. The capsaicin-only group (control rats without daily stimulation) showed hyperalgesia lasting for 3 days. In contrast, hyperalgesia persisted for 2 weeks in the group that received vibration stimulation. Neither the soft brush nor the pressure group showed a significant difference in mechanical threshold from the control group (capsaicin only). The vibration-induced prolonged hyperalgesia was significantly reduced by systemic injection of ifenprodil, an NMDA-receptor antagonist, but it was not influenced by either an AMPA-receptor blocker or a reactive oxygen species (ROS) scavenger. Furthermore, a dorsal column lesion did not interfere with the prolongation of hyperalgesia. Data suggest that vibration-induced prolongation of hyperalgesia is mediated by spinal NMDA-receptors, and a similar mechanism may underlie some forms of chronic pain with no obvious causes, such as complex regional pain syndrome type 1 (CRPS-1).     

The effects of payment method on clinical decision-making: physician responses to clinical scenarios

BACKGROUND: The influence of payment mechanisms on physician decisions is not well understood. OBJECTIVES: The objective of this study was to test 2 null hypotheses: 1) physicians' clinical decisions would not be influenced by payment incentives; and 2) physicians would have equal concern about medical decisions made under capitation or fee-for-service (FFS) arrangements. RESEARCH DESIGN: We conducted a physician survey in which patient insurance status (capitated or FFS) was randomly incorporated into 4 clinical scenarios using a Latin square design. SUBJECTS: We used a nationally representative random sample of family physicians in direct patient care. MEASURES: We used treatment decisions and physician "bother" scores (a measure of discomfort about decisions) in response to the clinical scenarios and adjusted for physician gender, age, board certification, income, practice location, practice mix, practice setting, geographic region, local area managed care penetration, and capitation or risk pool contracts in practice. RESULTS: Seventy-two percent of sampled physicians responded. Comparing decisions made under capitation to FFS, physicians were less likely to indicate they would perform discretionary care (relative risks [RR] range, .64-.82; P<0.001), but payment had no effect on selection of life-saving care (RR, 1.02, not significant). Physicians felt significantly more "bothered" when they made clinical decisions under capitated payment (P<0.001 in all scenarios), regardless of whether a treatment was discretionary or life-saving, and whether the decision was made for or against the treatment (P<0.001). CONCLUSIONS: Payment mechanism has significant effects on clinical decision-making. Reduction of resources spent for discretionary care might be achieved under capitated arrangements; however, physicians respond with greater levels of discomfort under capitation than FFS.     

The effects of detoxification, relaxation, and brief supportive therapy on chronic pain

Seven chronic pain patients (six with abdominal pain and one with headache pain) were detoxified from analgesic medications, taught relaxation techniques, and given an average of 3 supportive therapy sessions. The effects of these procedures at posttreatment and at 6 months follow-up were analyzed by means of self-report diaries of pain, mood, activity and medication usage. There was a significant reduction in pain from posthospital in 5 of 7 patients and a significant reduction in pain at 6-month follow-up for all patients. There was a significant reduction in medication use for all subjects. Mood ratings tended to improve when pain was reduced, and some patients reported increased activity levels. Detoxification combined with relaxation and supportive therapy appears to produce significant relief from pain for these 7 patients.     

Anti-atherosclerotic effects of calcium antagonists: a brief review

Drugs influencing calcium metabolism in animals fed high-fat diets may modify the progression of atherosclerosis. Agents that enhance calcium transport (catecholamines, vitamin D, parathyroid hormone) may accelerate atherogenesis. Conversely, agents with calcium chelating (diphosphonic acid and thiophene carboxylic acid derivatives), calcium channel blocking (dihydropyridine derivatives, verapamil and its derivatives, diltiazem), and anti-adrenergic (beta-blockers) properties have been demonstrated to suppress atherogenesis in rabbits and monkeys. Possible mechanisms of action include lowering of arterial pressure, minor changes in circulating lipoproteins, altered receptor-dependent lipoprotein uptake and lipoprotein metabolism, inhibition of cell migration and cell proliferation, and non-specific protection of injured cells in atheromatous lesions.     

The effects of relaxation training on clinical symptoms: a meta-analysis

Forty-eight experimental studies of nonmechanically assisted relaxation techniques used to control a variety of clinical symptoms were synthesized using meta-analysis. Effect sizes for three types of comparisons, experimental-control, experimental-placebo, and pre-post, ranged from .43 to .66, demonstrating that treatment of any type included in the analysis moved the client from the 50th to the 67th percentile of an untreated group at minimum and from the 50th to the 75th percentile at maximum. All treatments included in the analysis except Benson's relaxation technique demonstrated evidence of effectiveness, particularly for nonsurgical samples with chronic problems such as hypertension, headache, and insomnia.