Influence of the scattering phase function on light transport measurements in turbid media performed with small source-detector separations

Many methods of optical tissue diagnosis require that measurements be performed with small source-detector separations in a backscatter geometry. Monte Carlo simulations are used to demonstrate that for these situations light transport depends on the exact form of the angular scattering probability distribution, P(theta). Simulations performed with different forms of P(theta) with the same value of ?cos theta? result in the collection of significantly different fractions of the incident photons, particularly when small-numerical-aperture delivery and collection fibers are employed. More photons are collected for the distribution that has a higher probability of scattering events with theta > 125 degrees . For the clinically relevant optical parameters employed here, the differences in light collection are >60%.

Purification and properties of a monoacylglycerol lipase in human erythrocytes

A membrane-bound monoacylglycerol lipase (MAGL) activity, previously demonstrated in intact human erythrocytes [Boyer, Somma, Vérine, L'Hôte, Finidori, Merger and Arnaud (1981) J. Clin. Endocrinol. Metab. 53, 143-148], has now been purified to apparent homogeneity by a five-step procedure involving solubilization in CHAPS and sequential chromatographies on Sephacryl S-400, DEAE-Trisacryl, Zn(2+)-chelating Sepharose and Superose 12 columns. The purified protein has a molecular mass of 68 +/- 2 kDa, as determined by SDS/PAGE and gel filtration, suggesting that the enzyme behaves as a monomer. The concentration-dependence of MAGL activity with monooleoylglycerol, the preferred substrate showed kinetics typical of an interfacial lipolytic enzyme displaying optimal activity on emulsified substrate particles; apparent Km values were 0.27 mM and 0.49 mM for the sn-1(3)- and sn-2-isomers respectively. MAGL had no, or negligible, activity towards tri-oleoylglycerol, di-oleoylglycerol, oleoylcholesterol, oleoyl-CoA and phosphatidylcholine; it was inhibited by di-isopropylfluorophosphate, PMSF and diethyl p-nitrophenyl phosphate, suggesting that MAGL is a serine hydrolase. MAGL activity was not modified by bile salt or apolipoprotein C-II, whereas a dose-dependent inhibition was observed with apolipoprotein A-I.

DNA inoculation induces cross clade anti-HIV-1 responses

Nucleic acid or DNA immunization represents a novel approach to vaccine and immune therapeutic development. The direct injection of expression cassettes into a living host results in in vivo gene expression and immune activation. In the case of HIV-1 it has been shown by our laboratory that facilitated injection mimicks aspects of live attenuated vaccines and that both humoral and cellular responses can be induced upon injection of a nucleic acid sequence directly into a host target tissue. Antisera from HIV-1 plasmid expression cassette-immunized animals contain anti-HIV envelope glycoprotein immune responses. The antiserum neutralizes HIV-1 infection and inhibits cell to cell infection in vitro. Cellular immune responses have also been evaluated. We observed both T cell proliferation and isotype switching consistent with the production of relevant T helper immune responses in immunized animals. Furthermore it was demonstrated that CTL lysis of relevant env-expressing targets was similarly induced. These studies further define the importance of evaluating this new technology for vaccine and immune therapeutic development for HIV-1 as well as for other human viral pathogens.

Multicentre prospective controlled study of Barrett's oesophagus and colorectal adenomas. Groupe d'Etude de l'Oesophage de Barrett

Previous studies have suggested that patients with Barrett's oesophagus may be at increased risk of colorectal neoplasia, though the association is disputed. In a multicentre prospective study we compared the prevalence of colorectal adenomas in patients with Barrett's oesophagus and controls. Barrett's oesophagus patients (n = 104) had histological confirmation of columnar epithelium extending more than 3 cm above the gastro-oesophageal junction. The 537 controls were patients with symptoms suggesting irritable bowel syndrome. No participant had a personal history of colonic neoplasm. Each patient underwent colonoscopy. Histologically proven adenomas were found in 26 Barrett's patients (25%) and 75 controls (14%). Three colorectal cancers were discovered in each group. The prevalence of adenomas was greater in the Barrett's oesophagus group than in the control group (p < 0.01) but the relation became non-significant after adjustment for age and sex and control for other known risk factors by a logistic regression model (odds ratio 1.4 [0.7-2.7]). The relative risk of adenoma was significantly higher in patients older than 59 than in younger patients (2.2 [1.3-3.5]) and in men than in women (3.4 [2.0-5.7]). Other factors contributing significantly to the risk of adenoma were a family history of colorectal cancer (2.3 [1.1-4.8]), rectal bleeding (2.1 [1.1-3.9]), previous colonic investigation (0.3 [0.1-0.7]), and complete as opposed to partial colonoscopy (6.4 [0.8-48.3]). We conclude that Barrett's oesophagus is not an independent risk factor for colorectal neoplasia and, therefore, is not, in itself an indication for colorectal screening.

Antral motility in patients with cirrhosis with or without gastric antral vascular ectasia

Gastric motility has not been extensively studied in patients with cirrhosis and gastric antral vascular ectasia (GAVE) may be associated with antropyloric dysfunction. This study therefore looked at antral motility using ultrasound in patients with alcoholic cirrhosis with or without GAVE. Twenty six patients were included: 10 patients with cirrhosis without GAVE, eight patients with cirrhosis and GAVE, and eight controls without liver disease. Measurement of antral area and antral contractions (amplitude and frequency) was performed for three hours after ingestion of a standardised solid-liquid meal. Antral area half time (mean (SD)) was not significantly increased in patients with cirrhosis without GAVE (84 (42) min), but increased by 120% (123 (43) min; p < 0.01) in patients with GAVE compared with controls (56 (26) min). GAVE patients exhibited the same frequency and amplitude of antral contractions at each time point as controls and had the same tendency to increase these values over time although this was attenuated in the late postprandial phase. In contrast, cirrhotic patients without GAVE exhibited a significantly higher frequency and amplitude of antral contractions during the initial postprandial phase but showed no change in either frequency or amplitude over time. In conclusion, in cirrhosis there is an abnormal antral motor response to a meal, which has a different pattern over time in patients with or without GAVE.

High-affinity interaction of long-chain fatty acids with serum albumin in nephrotic syndrome

1. We have examined the effect of hypoalbuminaemia, a hallmark of nephrotic syndrome, on the albumin-fatty acid equilibrium in the plasma of 11 adult patients with nephrosis compared with 12 healthy subjects and six subjects with normoalbuminaemic hyperlipoproteinaemia. 2. We used a dialysis exchange rate method which allows the evaluation in relative terms of the binding affinity of albumin for plasma fatty acid and the fatty acid availability, tentatively equated with the unbound fatty acid fraction. 3. In nephrotic patients, an increase (P < 0.001) in albumin affinity for fatty acid was seen compared with healthy subjects, which was negatively correlated with albuminaemia (r = -0.69, P < 0.02). No change in fatty acid availability was seen for the group as a whole, but individual values showed a wide scatter, with the highest values in four patients with the highest fatty acid-albumin molar ratios. The increase in albumin affinity for fatty acid was specific to nephrotic syndrome since no such effect was seen in subjects with hyperlipoproteinaemia, who only showed a moderate increase (P < 0.01) in fatty acid availability. 4. The increased albumin affinity for fatty acid in nephrotic syndrome supports the hypothesis that an albumin component with lower affinity for fatty acid might filter out through the diseased glomerular membrane and leave the high-affinity albumin in plasma.

Colonic investigations in the elderly: colonoscopy or barium enema?

Colonoscopy (CS) is currently considered the best diagnostic procedure for colonic imaging. The objectives of this multicentric study were to assess whether CS or simple contrast barium enema (SCBE) has the best effectiveness and tolerance in the elderly (over 80 years old). Except in cases of emergency, 67 elderly patients from 3 centers were randomized among three diagnostic strategies: CS, SCBE or barium enema+rectosigmoidoscopy (BERS). CSs were generally carried out after polyethylene-glycol (PEG) cleansing, and barium enemas after enema cleansing. The diagnostic effectiveness of the three strategies was not significantly different: a colonic abnormality was found in CS, SCBE, BERS groups in 65, 56 and 71% of the cases, respectively. No other investigation was needed in 61 to 76% of cases, and, on the basis of the exploration, final therapy was modified in less than 22% of cases. Overall cleansing quality was significantly better with barium enema (84.1%) than with CS (57.0%; p < 0.05). This was explained by a poor tolerance to PEG intake, which led to 28.2% of adverse effects, compared with 7.1% after enema preparation (p < 0.05). This resulted in a significantly higher failure rate of complete colonic exploration with CS (48%) than with barium enema (9%; p < 0.001). In conclusion, the effectiveness of the three diagnostic strategies is similar in the elderly. However, due to a better acceptance of the enema preparation, and to a better success rate of complete exploration, SCBE should be preferred to investigate colonic symptoms when the above preparations are used.

Induction of humoral and cellular immune responses to the human immunodeficiency type 1 virus in nonhuman primates by in vivo DNA inoculation

DNA inoculation has the potential to produce antigens in a native as well as a host-"customized" form for presentation to the immune system. As such this technology may have relevance for vaccine/immune therapeutic strategies for a variety of infectious pathogens. In rodents in vivo inoculation of plasmid expression vectors encoding HIV-1 gene products leads to production of HIV-1 antigens in vivo, resulting in the production of both cellular and humoral immune responses. In primates only preliminary studies of serology have been reported. Here we report further evaluation of this new technology as a method to induce humoral and particularly cellular immune responses against a human pathogen, the HIV-1 virus, in nonhuman primates. Following inoculation and boosting of animals with an HIV gp160 plasmid expression vector we observed the induction of neutralizing responses against two diverse HIV-1 isolates in 2 of 3 vaccinated animals. T cell proliferative responses to HIV antigens were also observed in all plasmid-inoculated animals and specific cross-reactive cytotoxic T lymphocyte responses were developed in vaccinated animals. This report establishes the ability of DNA inoculation to induce cellular immune responses in nonhuman primates and suggests that further investigation of this technology with regard to human vaccine or immune therapeutic development is therefore warranted.

Reversible inhibition by ethanol of Mg(2+)-dependent phosphatidate phosphohydrolase: an in vitro study in the rat reticulocyte

By using a tracer method, we demonstrate that short-term in vitro exposure of intact rat reticulocytes to ethanol elicits a biphasic response of cell-bound Mg(2+)-dependent phosphatidate phosphohydrolase (PAP). An initial concentration-dependent (200-750 mM) activity decrease is rapidly (< 10 min) followed by reversal of the inhibition in the presence of ethanol, suggesting the development of a cell resistance to the inhibitory agent. Addition to the cell suspension of propranolol (100 microM), a known PAP inhibitor, does elicit PAP inhibition but unlike ethanol, inhibition is not followed by a return with time to control value. Ethanol-induced inhibition of cell-bound PAP was also demonstrated in cell-free extracts, where the Mg(2+)-dependent activity was decreased both in the particulate and soluble fractions. In the intact cells, the transient PAP inhibition occurs in concomitance with an overall increase in total glycerolipid biosynthesis, which is constant over 60-min incubation. We suggest that the biphasic mode of response to ethanol of Mg(2+)-dependent PAP activity may play a role in the mechanism of membrane adaptation to ethanol, and thereby to the pathogenesis of alcoholism.

Differential in vitro effects of ethanol on glycerolipid acylation and biosynthesis in rat reticulocytes

Earlier reports have shown that, in human and rat red blood cells (RBC), ethanol modulates acylation reaction sin several membrane glycerolipid components. Little is known, however, about the kinetics and the mechanisms involved in the acylation changes. In the present study, we show that short-term in vitro exposure of intact rat reticulocytes to ethanol differentially modifies within minutes the incorporation of [3H]oleic acid in glycerolipids. A concentration-dependent inhibition of acyl incorporation was measured in phosphatidylcholine (PC) and phosphatidylethanolamine (PE). This effect did not involve inhibition of the corresponding acyltransferase activities and is likely to be due to ethanol-dependent decreases in phospholipase activities. In contrast, ethanol markedly stimulated [3H]oleic acid incorporation in phosphatidic acid (PA), diacylglycerol (DG) and, to a lesser extent, in triacylglycerol (TG). To determine the mechanisms of the latter increases, reticulocytes were pulsed with [14C]glycerol and assayed as a function of time for labeled biosynthetic precursors and products. We observed a very close correlation between time courses and amplitudes of the ethanol stimulation of acylation and biosynthesis reactions, suggesting that stimulation of acylation in PA, DG and TG is causally related at least partly to their increased biosynthesis. Further studies revealed that increases in glycerolipid acylation and biosynthesis in reticulocytes were: (a) readily reversible upon ethanol withdrawal; (b) detectable for clinically relevant concentration (50 mM) of ethanol; and (c) associated with concomitant increases in cell resistance to hemolysis. These changes may be relevant to the development of tolerance to ethanol.

Alcohol and injury. A case-crossover study

OBJECTIVE

To determine whether and to what extent alcohol consumption increases the risk of injury.

DESIGN

The case-crossover study is a new research design for assessing rare acute events (such as trauma) in relation to intermittent exposures (such as alcohol use) that have transient effects. All interviewed patients serve as their own controls, and the study design compares exposure during a "case" period, such as the 6 hours prior to injury, with exposure during a "control" period, such as the same 6-hour window on the previous day.

SETTING

Emergency centers of a university hospital and a private not-for-profit hospital in a small midwestern city.

PATIENTS

Three hundred fifty adults who presented with an injury within 48 hours of the event.

DATA COLLECTED

Retrospective self-report of alcohol use in each of the 28 days and each of the 30 hours prior to injury, demographic variables, drug use prior to injury, patients' attributions regarding causes of their injury, and weather factors.

RESULTS

Primary analysis was based on pairs of observations that were discordant for alcohol use in the 6 hours prior to injury and the same 6-hour window on the previous day. The odds ratio for one or more standard drinks vs none was 2.5 (95% confidence interval, 1.2 to 5.4); for four or more drinks vs three or fewer, 5.0 (95% confidence interval, 1.4 to 27).

CONCLUSION

Alcohol use in the 6 hours prior to injury is associated with an increased risk of injury. The findings are consistent with a dose-response effect, but with this sample size no threshold of risk was found.

[Evaluation of the teaching of echo-endoscopy. Application to the assessment of invasiveness of cancer of the esophagus and the cardia]

OBJECTIVES

Learning endosonography (EES) is known to be difficult, and the theory must be understood before performing EES routinely. The aim of the study was to evaluate the diagnostic indexes of EES in the staging of cardio-oesophageal cancer after a period of theoretical apprenticeship of EES and a learning period in a centre experienced in EES since 1989.

METHODS

Five observers, having never used EES, followed to EES examinations for a 3-6 month period. They then reviewed the standardized records of 29 patients with cardio-oesophageal cancer. They had to evaluate the degree of tumour infiltration within oesophageal wall and the site of metastatic lymph nodes. Results were compared with the diagnosis of 5 experienced senior endoscopists. Interobserver agreement was estimated with kappa statistics and considered excellent for k > or = 0.75, good to moderate if 0.75 > k > or = 0.40, and poor if k < 0.40.

RESULTS

Inter-observer agreement was poor for the topographic diagnosis of lymph nodes (kappa index from -0.09 to 0.33), lower to that of the 5 senior observers (0.33 to 0.77). It was satisfactory for degree of tumour infiltration (T1: k = 0.66; T2: k = 0.58; T3: k = 0.56; T4: k = 0.46). The individual sensitivities were weak according to lymph nodes site, but good for presence of lymph nodes (86 to 100%), with a specificity of 40 to 73%.

CONCLUSIONS

After theoretical training of EES, agreement and diagnostic performances are good enough to diagnose pathological images (except for T4 tumors), and poor for localizing images in the mediastinum. This emphasizes the difficulties in learning echo-anatomy and gives useful guidelines for training programs in EES.

Spectroscopic diagnosis of bladder cancer with elastic light scattering

BACKGROUND AND OBJECTIVES

Recently, significant progress has been made toward the development of optical, noninvasive medical diagnostics. The goal of this study was to evaluate elastic scatter measurements as a tool for diagnosing bladder cancer.

STUDY DESIGN/MATERIALS AND METHODS

In vivo measurements on 10 patients with suspected bladder cancer were made with the optical biopsy system (OBS) developed at Los Alamos National Laboratory. Elastic-scatter spectra over the wavelength range 250-800 nm were obtained using a fiber-optic probe through one of the lumens of a urological cystoscope. Measurements were made on putatively normal areas and areas of uncertain abnormality, as well as those suspected to be cancerous. After measurements were made with the OBS, biopsy samples were taken at the measurement sites. Comparisons of the histopathology and the optical spectra were then made.

RESULTS AND CONCLUSIONS

A diagnostic algorithm for distinguishing malignant from nonmalignant tissue based on the values of the slopes over the wavelength range 330-370 nm has a sensitivity of 100% and specificity of 97% for the limited number of patients in this study.

Facilitated DNA inoculation induces anti-HIV-1 immunity in vivo

Vaccine design against HIV-1 is complicated both by the latent aspects of lentiviral infection and the diversity of the virus. The type of vaccine approach used is therefore likely to be critically important. In general, vaccination strategies have relied on the use of live attenuated material or inactivated/subunit preparations as specific immunogens. Each of these methodologies has advantages and disadvantages in terms of the elicitation of broad cellular and humoral immune responses. Although most success has been achieved with live attenuated vaccines, there is a conceptual safety concern associated with the use of these vaccines for the prevention of human infections. In contrast, subunit or killed vaccine preparations enjoy advantages in preparation and conceptual safety; however, their ability to elicit broad immunity is more limited. In theory, inoculation of a plasmid DNA that supports in vivo expression of proteins, and therefore presentation of the processed protein antigen to the immune system, could be used to combine the features of a subunit vaccine and a live attenuated vaccine. We have designed a strategy for intramuscular DNA inoculation to elicit humoral and cellular immune responses against expressed HIV antigens. Uptake and expression are significantly enhanced if DNA is administered in conjunction with the facilitating agent bupivacaine-HCl. Using this technique we have demonstrated functional cellular and humoral immune responses against the majority of HIV-1 encoded antigens in both rodents and non-human primates.

Complete DNA sequence of yeast chromosome XI

The complete DNA sequence of the yeast Saccharomyces cerevisiae chromosome XI has been determined. In addition to a compact arrangement of potential protein coding sequences, the 666,448-base-pair sequence has revealed general chromosome patterns; in particular, alternating regional variations in average base composition correlate with variations in local gene density along the chromosome. Significant discrepancies with the previously published genetic map demonstrate the need for using independent physical mapping criteria.

DNA inoculation as a novel vaccination method against human retroviruses with rheumatic disease associations

There are a number of rheumatologic manifestations of human retroviral infections associated with human immunodeficiency virus type I (HIV-I) and the human T-cell leukemia virus type I (HTLV-I) including arthritis, Sjøgren's syndrome-like symptoms as well as other varied autoimmune phenomena. Infection with HTLV-1 may be directly involved in the etiology and/or pathogenesis of an arthritic condition similar to rheumatoid arthritis. We have been characterizing a new vaccination strategy against human retroviral infections, designated DNA inoculation. This procedure involves the intramuscular injection of DNA plasmids which express specific human retroviral antigens. This technique results in the development of humoral and cellular immune responses against these proteins. Specifically, this method has been successfully used to develop immune responses against HIV-I and HTLV-I. The availability of rat and rabbit infection models for HTLV-I, coupled with the successful development of immune responses in these animals after DNA inoculation with an HTLV-I envelope expressing plasmid, will allow the efficacy of this vaccination technique to be evaluated with protection against in vivo viral challenge as an endpoint.