The effects of small-dose ketamine on propofol sedation: respiration, postoperative mood, perception, cognition, and pain.

We compared the effects of coadministration of propofol and small-dose ketamine to propofol alone on respiration during monitored anesthesia care. In addition, mood, perception, and cognition in the recovery room, and pain after discharge were evaluated. In the Propofol group (n = 20), patients received propofol 38 +/- 24 microg x kg(-1) x min(-1). The Coadministration group (n = 19) received propofol 33 +/- 13 microg x kg(-1) x min(-1) and ketamine 3.7 +/- 1.5 microg x kg(-1) x min(-1). Respiration was assessed by using end-expiratory PCO(2) measurements at nasal prongs. After surgeries, mood, perception, and thought were assessed by using visual analog scales, and cognition was assessed by Mini-Mental State Examination (MMSE). Pain after discharge was assessed by a five-point rating scale in the evening for 5 days. End-expiratory PCO(2) was lower in the Coadministration group (P < 0.0001). Mood and MMSE scores were higher in the Coadministration group (P < 0.004 and P = 0.001, respectively). Pain scores and analgesic consumption after discharge were less in the Coadministration group (P = 0.0004 and P < 0.0001, respectively). We conclude that coadministration of small-dose ketamine attenuates propofol-induced hypoventilation, produces positive mood effects without perceptual changes after surgery, and may provide earlier recovery of cognition.

Genetic analysis of a mammalian wound-healing trait.

Wound healing of mammalian tissue is an essential process in the maintenance of body integrity. The general mechanism of wound healing usually studied in adult mammals is repair, in contrast to the regeneration seen in more primitive vertebrates. We recently have discovered that MRL/MpJ mice, unlike all other strains of mice tested, undergo rapid and complete wound closure that resembles regeneration. Specifically, through-and-through surgical ear hole wounds close without scarring in <4 weeks with normal gross and microanatomic architecture, including chondrogenesis. We also demonstrated that this healing is a heritable trait in inbred mice. In this study, we present results pertaining to its genetic control in progeny segregating for this phenotype. To identify the genetic loci that control the wound closure process, a genome-wide scan was performed on (MRL/MpJ-Faslpr x C57BL/6)F2 and backcross populations. In the primary screens of these populations, quantitative trait loci that control the extent of wound closure were detected on chromosomes 8, 12, and 15 and at two separate locations on chromosome 13. Evidence of further genetic control of healing was found on chromosome 7. All alleles that contribute to full wound closure are derived from the MRL/MpJ-Faslpr parent except for the quantitative trait locus on chromosome 8, which is derived from C57BL/6.

A new murine model for mammalian wound repair and regeneration.

Regeneration is generally considered to be a phenomenon restricted to amphibians in which amputated limbs reform and regrow. We have recently noted a strain of mouse, the MRL, which displays a remarkable capacity for cartilagenous wound closure and provides an example of a phenomenon previously considered to be a form of regeneration. Specifically, through-and-through ear punches rapidly attain full closure with normal tissue architecture reminiscent of regeneration seen in amphibians as opposed to scarring, as usually seen in mammals. Histologically, we have demonstrated normal cell growth and microanatomy, including angiogenesis and chondrogenesis, as opposed to control C57BL/6 mice which have ear holes that contract minimally but do not close. Finally, this phenomenon is a genetically definable quantitative trait.

An evaluation of breastfeeding promotion through peer counseling in Mississippi WIC clinics.

OBJECTIVE: This study evaluates the effectiveness of a peer counseling program at increasing breastfeeding by participants in the Mississippi Special Supplemental Nutrition Program for Women, Infants and Children (WIC). METHODS: Data from the 1989-1993 Pediatric Nutrition Surveillance System were analyzed to compare breastfeeding rates in clinics with and without peer counseling programs. A questionnaire completed by program staff to describe the program in greater detail helped identify characteristics associated with greater success. RESULTS: The incidence of breastfeeding rose from 12.3% to 19.9% in those clinics with peer counseling programs, but only from 9.2% to 10.7% in clinics without a program. Clinics that started a program earlier showed greater changes in breastfeeding incidence. However, the presence of lactation specialists or consultants in the clinic appeared to be more important than the presence of less-trained peer counselors. Peer counselors who spent more than 45 minutes per participant were more effective than those spending less time. CONCLUSIONS: The peer counseling program significantly increased the incidence of breastfeeding, particularly in clinics with lactation specialists and consultants. Success can be enhanced by ensuring that peer counselors spend a great deal of time with the participants.

Factors influencing the biocompatibility of insertable silicon microshafts in cerebral cortex.

Insertable microelectrode arrays can be used to activate neurons or to sense neural signals for use in prosthetics. The relationship of the microelectrodes to the neurons is determined by random alignment and by biocompatibility. Issues that determine the biocompatibility of insertable microelectrode arrays were investigated. Arrays were implanted into the cortex of rabbit brain and fixed to the skull. Following six-month survival, neuron density as a function of distance from the shafts of the arrays was measured to assess destruction of neurons. Results from a limited number of tests indicated that there was minimal tissue response along the sides of the shafts when shafts were well sharpened, had sufficiently small tip angles, and were clean. Tissue was usually more reactive at the tips of the shafts. It was concluded that silicon microshafts of appropriate shaft and tip design were biocompatible along the sides of the shaft, but that relatively severe reactions could be anticipated at the tips. Recording or stimulation sites should be located away from the tips on the sides of the shafts for better coupling with individual neurons. Measurement of neuron density as a function of distance from the shafts was a sensitive and quantitative technique for assessing biocompatibility. Additional measures such as glial density as a function of distance from the shafts, and incidence of microhematoma formation were proposed.

Validation of a nutrient adequacy score for use with women and children.

The purpose of this study was to develop and validate a nutrient adequacy score to be used by nutrition programs for women and children. The study population included 1,431 children, teenagers, and pregnant and lactating women. A dietary score was developed to be limited if certain targeted subgroups of major food groups were not included. Scores were related to Mean Adequacy Ratios (MARs), truncated indexes of the percent of the Recommended Dietary Allowances for protein, calcium, iron, magnesium, phosphorus, vitamin A, thiamin, riboflavin, vitamin B-6, vitamin B-12, and vitamin C through the use of correlation/regression analysis. Separate analyses were run for each of nine different population segments. Regression coefficients were used to generate predicted MAR values that were, in turn, used to categorize individuals according to certain cut-off points. Individuals were also categorized by their actual MARs, according to the same cut-off points. These categorizations provided the basis for validating the score. The score correctly classified 69% to 98% of the persons in each population segment. The score was most sensitive for population segments that have a large proportion of persons below a particular cut-off. Just as important, the score was simple to implement, requiring just three steps from assessing the food frequency to determining risk.

Incompetence to refuse treatment: a necessary condition for civil commitment.

The recent U.S. District Court decision in A.E. and R.R. v. Mitchell held that psychiatric patients who are civilly committed under the Utah statute have no constitutional right to refuse treatment for the mental illness that led to their commitment. This unique law incorporates a judicial determination of competency to refuse treatment at the time of the commitment hearing and thus circumvents the objection to involuntary treatment raised in Rogers v. Okin. A number of psychiatrists have urged the use of this determination of competency, and recently the U.S. Court of Appeals for the First Circuit held it to be the sine qua non for the state's use of parens patriae power in compelling committed patients to accept neuroleptic medication.

Further evidence for an argyrophilic fourth cell type in the pancreatic islet of the rat.

An argyrophilic fourth cell type in fetal and adult rat pancreatic islets can be identifed by using a modification of the Grimelius silver statin. This cell is much more abundant in the fetal pancreas than in the adult. By employing the modified silver technique followed by restaining with the indirect immunofluorescent procedure for somatostatin, the content of this argyrophilic fourth cell was studied further. Comparison of these histochemical studies demonstrated that somatostatin was not located in the fourth cell of either the adult or fetal rat pancreas. These results indicate that the D-cell and the fourth cell type are not the same cell. Thus far the only product associated with this argyrophilic cell is pancreatic polypeptide. As a result this cell probably represents the PP-cell of the Wiesbaden classification.

The staining of pancreatic delta cells for light microscopy.

Three staining techniques--Hellerström-Hellman alcoholic silver nitrate, pseudoisocyanin, and the immunofluorescent technique for somatostatin--were compared to determine whether they are staining the same cell in the pancreatic islet of the rat. These comparisons were made by using staining and restaining procedures on the same islet. The results demonstrate that all three procedures stain the delta cell of the rat pancreatic islet. Some advantages of using pseudoisocyanin are discussed.

Behavioral correlates of social dominance.

The behavioral correlates of dominance in the squirrel monkey were explored using a variety of operant tasks. Compared to more submissive animals, more dominant ones showed higher operant rates, more consistent work output, and a higher degree of "frustration tolerance." These data suggest that dominance in the squirrel monkey is not related solely to physical size, but to a variety of behavioral traits which lead to more adjustive problem-solving behavior.