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H Smits

Publications and source records attributed to H Smits.

10 recordsLinked to original sources
PubMed2006

Effect of spinal cord stimulation in an animal model of neuropathic pain relates to degree of tactile "allodynia".

Spinal cord stimulation (SCS) is an established treatment for chronic neuropathic pain. However, in recent studies conflicting results regarding the effect of SCS were noted in a selected group of patients suffering from complex regional pain syndrome and mechanical allodynia. In the present study we investigated the pain relieving effect of SCS in a rat experimental model of neuropathic pain as related to the severity of mechanical allodynia. Adult male rats (n=45) were submitted to a unilateral sciatic nerve ligation. The level of allodynia was tested using the withdrawal response to tactile stimuli with the von Frey test. A portion of these rats developed marked tactile hypersensitivity in the nerve-lesioned paw (von Frey test), similar to "tactile allodynia" observed after nerve injury in humans. Prior to SCS treatment the rats were subdivided into three groups based on the level of allodynia: mild, moderate and severe. All allodynic rats were treated with SCS (n=27) for 30 min (f=50 Hz; pulse width 0.2 ms and stimulation at 2/3 of motor threshold) at 16 days post-injury. Our data demonstrate a differential effect of SCS related to the severity of the mechanical allodynia. SCS leads to a faster and better pain relief in mildly allodynic rats as compared with the more severely allodynic rats. Thus, we suggest that the selection and subdivision of patient groups similar to those defined in our experimental setting (mild, moderate and severe allodynic) may provide better pre-treatment prediction of possible therapeutic benefits of SCS.

Animals↗
PubMed1985

Regulation of differentiation of tracheal epithelial cells by retinoids.

An in vitro culture system of rabbit tracheal epithelial cells has been developed to study the regulation of differentiation of the respiratory epithelium on the molecular level. At high density in the absence of retinoids these cells become squamous, stratify, and ultimately form cross-linked envelopes. Several factors influence this terminal differentiation: high Ca2+ concentrations and serum factors promote, whereas retinoids and medium conditioned by fibroblasts inhibit this process. Terminal squamous cell differentiation is accompanied by several biochemical changes: the synthesis of proteoglycans is dramatically reduced and the expression of keratin intermediate filaments is altered. Besides the eight major keratins expressed in undifferentiated cells, terminally differentiated cells also express a 48 kDa keratin. The expression of this keratin correlates well with squamous cell differentiation and appears to be under the control of retinoic acid. The level at which these biochemical changes are regulated has yet to be established. Specific retinol- and retinoic acid-binding proteins have been identified in these cells; the correlation between binding and biological activity of retinoids in this system is in agreement with a role for these binding proteins in mediating the action of these agents.

Animals↗
PubMed1977

Computer-based audit to detect and correct overutilization of laboratory tests.

We developed a computer-bases system to detect inappropriate use of the clinical laboratory and tested a program of physician education to reduce overutilization. We modified the hospital laboratory's computerized reporting system to identify medical patients with three or more determinations of lactic dehydrogenase (LDH) or calcium during the preceding seven days. We audited the charts of these patients, using explicit criteria, to determine whether multiple studies were justified. During the control period 51 per cent of the charts audited for multiple determinations of LDH revealed overutilization. During the study period, when physicians were notified if overutilization was found, 65 per cent of the charts showed overutilization. This difference was not significant. A simultaneous, undisclosed audit of calcium determinations also showed no change between the two periods. Therefore, this method is effective in detecting and measuring overutilization of the laboratory. It is a method which is easily adaptable to a hospital's computerized laboratory reporting system, and it can be applied without a computer. However, our program of notification and education of physicians is not effective in reducing overutilization. More effective methods of modifying physicians' use of laboratory tests need to be developed.

Calcium↗