The alpha2-adrenergic receptor antagonist idazoxan reduces dyskinesia and enhances anti-parkinsonian actions of L-dopa in the MPTP-lesioned primate model of Parkinson's disease

Dopamine replacement therapy in patients with Parkinson's disease is plagued by the emergence of abnormal involuntary movements known as L-dopa-induced dyskinesias. It has been demonstrated that yohimbine can reduce L-dopa-induced dyskinesia in the MPTP-lesioned primate model of Parkinson's disease. Yohimbine is, among other things, an alpha-adrenergic receptor antagonist. In this study, we demonstrate that the selective and potent alpha2-adrenergic receptor antagonist idazoxan reduces L-dopa-induced dyskinesia in the MPTP-lesioned marmoset model of Parkinson's disease. The alpha2-adrenergic receptor antagonists rauwolscine and yohimbine also reduce L-dopa-induced dyskinesia. Furthermore, we demonstrate that coadministration of idazoxan with L-dopa can provide an anti-parkinsonian action more than twice the length of that seen with L-dopa alone. However, idazoxan as a monotherapy displayed no anti-parkinsonian actions. We propose that idazoxan in combination with L-dopa may provide a novel approach to the treatment of Parkinson's disease that will not only reduce the dyskinetic side effects, but extend the anti-parkinsonian actions of L-dopa. Idazoxan, as an adjunct to dopamine replacement, may prove useful in the treatment of parkinsonian patients at all stages of disease progression.

Strategies to prevent organ failure

The gastrointestinal tract and the generalized inflammatory response initiated by severe injury or infection have been implicated in the pathophysiology of multiple-organ system failure. Once multiple-organ system failure has occurred, treatment focuses on supporting end-organ function. Recent studies have shown, however, that it may be possible to reduce the incidence and prevalence of multiple-organ system failure by controlling the reperfusion injury cascade, normalizing gastrointestinal blood flow and preserving the integrity of the gastrointestinal immune barrier.

Angiogenesis in normal tissue adjacent to colon cancer

BACKGROUND AND OBJECTIVES

Angiogenesis in malignant neoplasms, as measured by microvessel density, has been shown to correlate with survival or stage in some studies of breast, gastric, and colorectal cancer. We hypothesized that aggressive cancers promote angiogenesis in normal tissue adjacent to the invading neoplasm.

METHODS

To test this hypothesis, 36 specimens of colon adenocarcinoma curatively resected between 1986 and 1990 were sectioned and stained for factor VIII-related antigen, vascular endothelial growth factor (VEGF), and interleukin-8 (IL-8). Microvessel density was measured within the colon cancer and in adjacent, histologically normal tissue. Clinical/pathological variables were examined using multivariate analysis and Student t-test.

RESULTS

Microvessel density was higher in the neoplasms (26.0+/-1.66/ 0.25 mm2) than in the surrounding normal tissue (22.3+/-1.88/0.25 mm2) (P=0.03). The difference was primarily due to smaller neoplasms (T1 and T2) which had vessel counts of 10.6+/-0.74/0.25 mm2 in the adjacent normal tissue compared to vessel counts of 18.9+/-3.02/0.25 mm2 within these tumors (P=0.02). T3 and T4 neoplasms had equivalent amounts of angiogenesis within the lesion (26.9+/-1.81/0.25 mm2) and in the histologically normal margin (24.2+/-1.98/0.25 mm2) (P=0.12). VEGF was present in the tumor microenvironment in 100% and IL-8 in 45% of specimens stained for these angiogenic cytokines. Microvessel density did not correlate with 5-year survival.

CONCLUSIONS

Our data suggest that colon cancers that invade through the muscularis propria may have a greater ability to induce angiogenesis in adjacent normal tissue.

Angiogenesis in normal tissue adjacent to colon cancer

BACKGROUND AND OBJECTIVES

Angiogenesis in malignant neoplasms, as measured by microvessel density, has been shown to correlate with survival or stage in some studies of breast, gastric, and colorectal cancer. We hypothesized that aggressive cancers promote angiogenesis in normal tissue adjacent to the invading neoplasm.

METHODS

To test this hypothesis, 36 specimens of colon adenocarcinoma curatively resected between 1986 and 1990 were sectioned and stained for factor VIII-related antigen, vascular endothelial growth factor (VEGF), and interleukin-8 (IL-8). Microvessel density was measured within the colon cancer and in adjacent, histologically normal tissue. Clinical/pathological variables were examined using multivariate analysis and Student t-test.

RESULTS

Microvessel density was higher in the neoplasms (26.0+/-1.66/ 0.25 mm2) than in the surrounding normal tissue (22.3+/-1.88/0.25 mm2) (P=0.03). The difference was primarily due to smaller neoplasms (T1 and T2) which had vessel counts of 10.6+/-0.74/0.25 mm2 in the adjacent normal tissue compared to vessel counts of 18.9+/-3.02/0.25 mm2 within these tumors (P=0.02). T3 and T4 neoplasms had equivalent amounts of angiogenesis within the lesion (26.9+/-1.81/0.25 mm2) and in the histologically normal margin (24.2+/-1.98/0.25 mm2) (P=0.12). VEGF was present in the tumor microenvironment in 100% and IL-8 in 45% of specimens stained for these angiogenic cytokines. Microvessel density did not correlate with 5-year survival.

CONCLUSIONS

Our data suggest that colon cancers that invade through the muscularis propria may have a greater ability to induce angiogenesis in adjacent normal tissue.

Future directions in CT technology

Progress in helical CT acquisition and processing over the last 5 years has lead to new applications and new requirements. Recent progress to meet these requirements is discussed in this article. The potential of future acquisition developments and their potential to further import application are explored.

Behavioral effects of 5-HT2C receptor antagonism in the substantia nigra zona reticulata of the 6-hydroxydopamine-lesioned rat model of Parkinson's disease

Overactivity of the substantia nigra zona reticulata and the medial segment of the globus pallidus are responsible for the generation of symptoms in Parkinson's disease. Reducing the activity of these regions has been shown to be a viable alternative to dopamine replacement in the symptomatic treatment of Parkinson's disease. 5-HT2C receptors in the substantia nigra zona reticulata are excitatory. In this study we have shown that intracerebral infusion of the selective 5-HT2C receptor antagonist SB 206553 (50 nmol) into the substantia nigra zona reticulata has an antiparkinsonian action in the 6-hydroxydopamine-lesioned rat model of Parkinson's disease. SB 206553 did not affect locomotion when injected into the nonparkinsonian substantia nigra. Furthermore, we have demonstrated that systemic administration of selective 5-HT2C receptor antagonists SB 200646A (20 mg/kg) and SB 206553 (20 mg/kg) can potentiate the antiparkinsonian action of the dopamine D2 receptor agonist quinpirole in the 6-hydroxydopamine-lesioned rat. Hence, 5-HT2C receptor antagonists may be useful adjuncts to dopamine agonists in the treatment of Parkinson's disease.

Simulated dose reduction in conventional chest CT: validation study

PURPOSE

To validate a technique of computer-simulated dose reduction for conventional chest computed tomography (CT).

MATERIALS AND METHODS

In 27 patients, CT scans were obtained at 200, 100, and 40 mAs at two levels. The raw data from the 200-mAs scan were modified on a computer workstation to simulate the increased noise present on 100- and 40-mAs scans. Real and simulated 100- and 40-mAs images were independently assessed in random order for overall image quality and radiologic findings by four subspecialty-trained chest radiologists who were blinded to the technique. The four observers were given paired real and simulated images. They were asked to identify the real image and note any difference in diagnostic quality.

RESULTS

No difference was seen in overall image quality or radiologic findings between real and simulated images (P > .05). In the paired comparison, 433 of 864 (50.1%) real images were correctly identified.

CONCLUSION

Computer modification of 200-mAs raw scan data to simulate 100- and 40-mAs noise levels produces reconstructed images indistinguishable from real 100- and 40-mAs scans. This technique provides realistic reduced-dose images without patient radiation exposure and with identical image registration and motion artifact.

The effect of helical pitch and beam collimation on the lesion contrast and slice profile in helical CT imaging

A model is presented in this paper to describe how the contrast of a reconstructed object and slice sensitivity profile are affected by (1) the table speed or helical pitch, (2) the x-ray collimations, (3) the size of the object, (4) the alignment between the reconstructed slice and the object, (5) the distance of the object from the axis of rotation, and (6) the helical CT reconstruction algorithm employed. This contrast model is validated by both computer simulations and experiments. With this model, the contrast of a reconstructed object, slice sensitivity profile, and the longitudinal MTF can be accurately predicted. The optimal scan strategy and the point of diminishing returns can be determined prior to scanning. Several conclusions can be drawn from this model. First, overlapping reconstruction significantly improves overall scan contrast sensitivity of helical CT. Second, with a given x-ray collimation, low pitch helical scans provide better longitudinal resolutions. Third, with a given volume coverage rate (i.e., a given table speed), narrow collimation high pitch helical scans provide better longitudinal resolutions than wide collimation low pitch ones and therefore are recommended for high-contrast thin-slice applications. A lesion conspicuity model is also established.

Helical CT of the liver: clinical application of an automated computer technique, SmartPrep, for obtaining images with optimal contrast enhancement

OBJECTIVES

The purpose of this study was to evaluate an automated computer technique (SmartPrep) for achieving a consistently high level of contrast enhancement in the liver with helical CT. The technique compensates for variability between patients by indicating graphically the time at which scanning should be initiated to reach a desired level of hepatic enhancement.

MATERIALS AND METHODS

One hundred nine consecutive patients undergoing helical CT of the abdomen were randomly evaluated, using either a standard 70-sec delay from the start of the injection of contrast material to scanning or a newly developed, commercially available automated technique, SmartPrep. A series of multiple low-dose scans was performed until an arbitrary threshold of hepatic enhancement (50 H) over baseline was achieved. Three regions of interest (ROIs) were imaged on a baseline scan and on contrast-enhanced scans at the upper, mid, and lower liver. Average hepatic enhancement and the standard deviation over baseline was calculated for each group at all anatomic levels. For the SmartPrep group, the range of time between scan initiation and onset of scanning was calculated.

RESULTS

The mean hepatic enhancement for the control group (n = 56) was 59.8 +/- 20.1 H, which differed significantly (p = .0002) from that for the SmartPrep group (n = 53), which was 71.6 +/- 15.2 H. Comparison of the variability between the two groups' enhancement levels was also significant (p = .02). The range of delay times for the SmartPrep group was 48-86 sec. In two additional cases, abnormal graphically displayed enhancement curves were the first indication of an improper injection.

CONCLUSION

Use of SmartPrep yields a greater and more consistent level of hepatic enhancement from patient to patient than does use of a conventional fixed delay time. The ability to scan more efficiently to achieve greater hepatic enhancement using SmartPrep has significant implications for potential contrast cost savings.

Distinct electric potentials in soma and neurite membranes

Structurally similar voltage-dependent ion channels may behave differently in different locations along the surface of a neuron. A possible reason could be that channels experience nonuniform electrical potentials along the plasmalemma. Here, we map the electrical potentials along the membrane of differentiated N1E-115 neuroblastoma cells with a potential-sensitive dye. We find that the intramembrane potential gradient is indeed more positive in the membranes of neurites than in the membranes of somata. This is not attributable to differences in ion conductances or surface charge densities between the membranes of neurites and somata; instead, it can be explained by differences in lipid composition. The spatial variation in intramembrane electrical potential may help account for electrophysiological and functional differences between neurites and somata.

Costing medical care: using Medicare administrative data

This paper describes how the PORTS are using data from the Medicare administrative records systems to study the medical care costs of specific conditions. The general strengths and weaknesses of the Medicare databases for studying cost related issues are discussed, and the relevant data elements are examined in detail. Changes in the nature of the data collected over time are noted. Information is provided on how the PORTS are using these data to estimate the cost to Medicare of treating Medicare beneficiaries with specific conditions and the social (opportunity) cost of treating these patients. Furthermore, information is provided on how data from the Medicare administrative records system can be used to determine the cost of services for patients who have been identified through other large databases (i.e., state hospital discharge tapes) or who have been enrolled in prospective cohort studies.

Birth weight and smoking during pregnancy--effect modification by maternal age

Cigarette smoking during pregnancy is an important, avoidable factor associated with low birth weight. Maternal age is also associated with variations in birth weight. Using birth certificate data from all 347,650 singleton births for which maternal age and birth weight were recorded during 1984-1988 in Washington State, this study investigated birth weight and smoking during pregnancy (yes/no) for mothers of different ages. In multiple linear regressions adjusted for race, marital status, parity, adequacy of prenatal care, and urban/rural residence, the decrement in mean birth weight associated with smoking grew steadily from 117 g for the youngest mothers (age less than 16 years) to 376 g for the oldest (age 40 years or more). Similarly, the adjusted relative risk of having a low weight birth (less than 2,500 g) for smokers compared with nonsmokers was lowest for mothers aged 16-17 years, at 1.43 (95% confidence interval 1.22-1.68), and increased steadily to 2.63 (95% confidence interval 1.77-3.90) for mothers aged 40 or more. This result suggests that the effect of exposure to cigarette smoking during pregnancy is modified by advancing maternal age. Further research using data that more precisely measure the exposure (cigarettes per day, years smoked) could help further clarify this issue and better address the public health question of whether smoking cessation programs ought to focus limited resources more selectively toward pregnant smokers in particular age groups.

GnRH cell size and number in a teleost fish with two male reproductive morphs: sexual maturation, final sexual status and body size allometry

Gonadotropin releasing hormone-like immunoreactive (GnRH-ir) cells in both the ganglion of the terminal nerve (TN) and the preoptic area (POA) have been implicated in the development and maintenance of reproductive behavior and physiology in teleost fishes. One marine species, the plainfin midshipman, Porichthys notatus, exhibits two sexually mature male morphs (types I and II) which differ with respect to size at sexual maturation, gonad/body weight index, reproductive tactic and vocal motor traits. Type II males become reproductively active at a smaller body size than either females or type I males. Immunocytochemical techniques and quantitative analyses were used here to determine the size and number of GnRH-ir cells in the TN and POA amongst field collected juveniles, sexually mature females, and type I and II males. Mean GnRH-ir cell size and number in the TN did not vary across the entire range of specimens. However, mean GnRH-ir cell size and number in the POA were 50-100% greater in sexually mature adults compared to juveniles. Analyses of covariance indicated that increases in cell number, but not cell size, could be explained solely on the basis of changes in body size. However, regression analyses showed that body size had a significant influence on increasing cell number only in the juvenile-type I male transition and the juvenile-female transition, not in the juvenile-type II male transition. The latter suggests that type II males, unlike the other adult morphs, have 'escaped' from a body size constraint imposed on increasing GnRH-ir cell number in the POA. There were also significant differences among the adult morphs in the size of GnRH-ir POA cells that could not be explained on the basis of differences in body size but, rather, appear to reflect differences in the temporal onset of sexual maturation. Together, the data suggest that the timing of changes in POA phenotype may provide a proximate mechanism permitting the development of alternative male reproductive morphs.

The effect of evaporative cooling of respiratory protective devices on skin temperature, thermal sensation, and comfort

High skin temperature of the face is a major source of discomfort while wearing respiratory protective devices. In this paper theoretical considerations of thermal exchange between the face and the environment with and without a mask are discussed to elucidate factors that may improve the design of masks to increase their acceptability. Comfort thresholds have been related to skin temperature for both resting and exercising subjects. Skin temperature below 34.5 degrees C at rest, and 31 degrees C during exercise, is rated as comfortable. In a previous study it was determined that evaporative cooling could reduce skin temperature and decrease discomfort in a dummy mask. In the present study evaporative cooling of a more sophisticated dummy mask and a modified Scott model 66 twin-cartridge respirator was tested in resting and exercising subjects. Skin temperature was significantly reduced when wet felt covered the surface of both masks and at rest the masks were rated as significantly more comfortable than with dry felt on the outer surface. It is concluded that evaporative cooling of an existing face mask can reduce skin temperature to the comfort threshold in resting subjects. Data suggest that similar results are attainable for exercising subjects.

Helical (spiral) CT of the abdomen

Since its clinical introduction in the mid 1970s, techniques for CT have undergone many changes that have dramatically altered how CT scans are obtained. Helical (spiral) CT allows for faster acquisition of truly volumetric CT data than is possible with conventional scanners. Routine helical CT of the abdomen is now possible because of three major technical refinements: the development of the slip-ring gantry, improved detector efficiency, and greater tube cooling capability. This article reviews the technical principles that govern helical CT, the potential advantages and disadvantages of this technique, and initial clinical experience with helical CT of the abdomen.

The risk of developing subsequent nonmelanoma skin cancers

Data from the Southeast Arizona Skin Cancer Registry collected during 1985 through June 1988 were used in this study. Patients who had a nonmelanoma skin cancer (basal cell or squamous cell carcinoma) removed in 1985 were observed until subsequent nonmelanoma skin cancers developed or until June 30, 1988. Twelve categories of nonmelanoma skin cancers were developed on the basis of the type of first nonmelanoma skin cancer and type of second, third, and fourth nonmelanoma skin cancers. Analyses showed the highest risk of a subsequent nonmelanoma skin cancer developing was within 1 year (36.39%), the rate of developing another nonmelanoma skin cancer depended on type (squamous cell carcinoma, 100%; basal cell carcinoma, 44.23% to 83.65%), and total risk decreased during the 1277 days of the study.

Thermal discomfort of respiratory protective devices

Respiratory protective devices which would protect the wearer against noxious material and gases are not worn in many of the appropriate circumstances. They have been said to feel uncomfortable and hot. In the present study, six men and six women in a 25 degrees C room reported on facial discomfort, thermal sensation, and sweating while wearing three different types of half-facepiece respirators requiring tidal airflow. Skin temperature of the face was measured using a thermocouple taped to the nasolabial fold. The subjects reported that the face felt comfortable when the skin temperature was 34 degrees C or below. However, at skin temperatures above 34.5 degrees C, the face felt increasingly warm, uncomfortable, and sweaty. This finding is similar to that reported previously when subjects wore a half-facepiece respirator supplied continuously with warm, humid air. The conclusion is that thermal conditions of the face contributed to, and may possibly dominate, the discomfort of wearing respiratory protective devices.

Perceptions of risks of smoking and heavy drinking during pregnancy: 1985 NHIS findings

As part of the Health Promotion and Disease Prevention Questionnaire administered in the 1985 National Health Interview Survey, nearly 20,000 respondents ages 18-44 answered questions about their awareness of the risks of smoking and heavy drinking during pregnancy. In reference to smoking, interviewers asked about miscarriage, stillbirth, prematurity, and low birth weight; in reference to heavy drinking, they asked about miscarriage, mental retardation, low birth weight, and birth defects, as well as fetal alcohol syndrome. For each of these adverse outcomes, a majority of subjects acknowledged increased risk because of smoking or heavy drinking during pregnancy. The range was 66-80 percent of respondents for the four questions on smoking, with the perceived association to smoking strongest for low birth weight. Approximately 84 percent of respondents associated heavy drinking with increased risk for each of the suggested pregnancy outcomes. Smoking seemed to be perceived to pose a lesser risk to pregnancy than heavy drinking. This relative lack of awareness of the pregnancy risks of smoking was more apparent among respondents with less education and more pronounced among blacks than whites. Women were more likely than men to express some opinion on these pregnancy-related questions and were more cognizant than men of the risks. On this limited survey, Americans ages 18-44 were not very knowledgeable about fetal alcohol syndrome. Among the 55 percent who had heard of fetal alcohol syndrome, fewer than one in four correctly identified it as a set of birth defects when offered three possible definitions. It will be interesting to correlate responses to these "knowledge" questions with NHIS data still forthcoming on reported actual smoking and drinking behavior among women respondents who were recently pregnant.

Sperm as an indicator of reproductive risk among petroleum refinery workers

A questionnaire study of men in a wastewater treatment plant of a petroleum refinery showed twice the rate of fetal loss in the period during employment in the plant compared with the periods before and after. Questions regarding the interpretation of that study and continuing concern about reproductive risk prompted us to perform a cross sectional evaluation of sperm concentration and morphology. After adjustment for an abstinence period, the mean sperm concentration of the 74 unexposed men did not differ significantly from that of the 34 exposed men (79.9 million/cm3 v 68.2 million/cm3, p(1) = 0.16). The two groups also had a similar proportion of sperm with abnormal morphology (49.1% v 44.5%, p(1) = 0.94). This lack of association remained when degree of exposure, age, use of alcohol and marijuana, past illness or fever, use of baths or sauna, and history of urological problems were considered. These results are most consistent with the absence of sperm mediated reproductive problems.

Some relatively simple steps toward a computer system for the analysis of two-dimensional gel-electrophoresis autoradiographs

A computerized system for the quantitative comparison of two-dimensional polyacrylamide gel autoradiographs is being developed that requires relatively limited hardware resources. Two fast, simple, and stable programs--one for background and streak subtraction and one for peak detection--have been developed and tested. Two methods developed by others--one for image smoothing and one for peak matching--also have been tested. A very simple spot-density integration program that works on isolated spots has been written and is being developed further.