Pharmacokinetic enhancement of inhibitors of the human immunodeficiency virus protease by coadministration with ritonavir

Coadministration with the human immunodeficiency virus (HIV) protease inhibitor ritonavir was investigated as a method for enhancing the levels of other peptidomimetic HIV protease inhibitors in plasma. In rat and human liver microsomes, ritonavir potently inhibited the cytochrome P450 (CYP)-mediated metabolism of saquinavir, indinavir, nelfinavir, and VX-478. The structural features of ritonavir responsible for CYP binding and inhibition were examined. Coadministration of other protease inhibitors with ritonavir in rats and dogs produced elevated and sustained plasma drug levels 8 to 12 h after a single dose. Drug exposure in rats was elevated by 8- to 46-fold. A > 50-fold enhancement of the concentrations of saquinavir in plasma was observed in humans following a single codose of ritonavir (600 mg) and saquinavir (200 mg). These results indicate that ritonavir can favorably alter the pharmacokinetic profiles of other protease inhibitors. Combination regimens of ritonavir and other protease inhibitors may thus play a role in the treatment of HIV infection. Because of potentially substantial drug level increases, however, such combinations require further investigation to establish safe regimens for clinical use.

BMI does not accurately predict overweight in Asian Indians in northern India

Asian Indians are at high risk for the development of atherosclerosis and related complications, possibly initiated by higher body fat (BF). The present study attempted to establish appropriate cut-off levels of the BMI for defining overweight, considering percentage BF in healthy Asian Indians in northern India as the standard. A total of 123 healthy volunteers (eighty-six males aged 18--75 years and thirty-seven females aged 20--69 years) participated in the study. Clinical examination and anthropometric measurements were performed, and percentage BF was calculated. BMI for males was 21.4 (sd 3.7) kg/m(2) and for females was 23.3 (sd 5.5) kg/m(2). Percentage BF was 21.3 (sd 7.6) in males and 35.4 (sd 5.0) in females. A comparison of BF data among Caucasians, Blacks, Polynesians and Asian ethnic groups (e.g. immigrant Chinese) revealed conspicuous differences. Receiver operating characteristic (ROC) curve analysis showed a low sensitivity and negative predictive value of the conventional cut-off value of the BMI (25 kg/m(2)) in identifying subjects with overweight as compared to the cut-off value based on percentage BF (males >25, females >30). This observation is particularly obvious in females, resulting in substantial misclassification. Based on the ROC curve, a lower cut-off value of the BMI (21.5 kg/m(2) for males and 19.0 kg/m(2) for females) displayed the optimal sensitivity and specificity, and less misclassification in identification of subjects with high percentage BF. Furthermore, a novel obesity variable, BF:BMI, was tested and should prove useful for interethnic comparison of body composition. In the northern Indian population, the conventional cut-off level of the BMI underestimates overweight and obesity when percentage BF is used as the standard to define overweight. These preliminary findings, if confirmed in a larger number of subjects and with the use of instruments having a higher accuracy of BF assessment, would be crucial for planning and the prevention and treatment of various obesity-related metabolic diseases in the Asian Indian population.

Optical scattering properties of soft tissue: a discrete particle model

We introduce a micro-optical model of soft biological tissue thatpermits numerical computation of the absolute magnitudes of itsscattering coefficients. A key assumption of the model is that therefractive-index variations caused by microscopic tissue elements canbe treated as particles with sizes distributed according to a skewedlog-normal distribution function. In the limit of an infinitelylarge variance in the particle size, this function has the samepower-law dependence as the volume fractions of the subunits of anideal fractal object. To compute a complete set of opticalcoefficients of a prototypical soft tissue (single-scatteringcoefficient, transport scattering coefficient, backscatteringcoefficient, phase function, and asymmetry parameter), we apply Mietheory to a volume of spheres with sizes distributed according to thetheoretical distribution. A packing factor is included in thecalculation of the optical cross sections to account for correlatedscattering among tightly packed particles. The results suggest thatthe skewed log-normal distribution function, with a shape specified bya limiting fractal dimension of 3.7, is a valid approximation of thesize distribution of scatterers in tissue. In the wavelength range 600 </= lambda </= 1400 nm, the diameters of the scatterers thatcontribute most to backscattering were found to be significantlysmaller (lambda/4-lambda/2) than the diameters of the scatterersthat cause the greatest extinction of forward-scattered light(3-4lambda).

Liver failure determines the outcome in patients of acute-on-chronic liver failure (ACLF): comparison of APASL ACLF research consortium (AARC) and CLIF-SOFA models

BACKGROUND AND AIMS

Acute-on-chronic liver failure (ACLF) is a progressive disease associated with rapid clinical worsening and high mortality. Early prediction of mortality and intervention can improve patient outcomes. We aimed to develop a dynamic prognostic model and compare it with the existing models.

METHODS

A total of 1402 ACLF patients, enrolled in the APASL-ACLF Research Consortium (AARC) with 90-day follow-up, were analyzed. An ACLF score was developed in a derivation cohort (n = 480) and was validated (n = 922).

RESULTS

The overall survival of ACLF patients at 28 days was 51.7%, with a median of 26.3 days. Five baseline variables, total bilirubin, creatinine, serum lactate, INR and hepatic encephalopathy, were found to be independent predictors of mortality, with AUROC in derivation and validation cohorts being 0.80 and 0.78, respectively. AARC-ACLF score (range 5-15) was found to be superior to MELD and CLIF SOFA scores in predicting mortality with an AUROC of 0.80. The point scores were categorized into grades of liver failure (Gr I: 5-7; II: 8-10; and III: 11-15 points) with 28-day cumulative mortalities of 12.7, 44.5 and 85.9%, respectively. The mortality risk could be dynamically calculated as, with each unit increase in AARC-ACLF score above 10, the risk increased by 20%. A score of ≥11 at baseline or persisting in the first week was often seen among nonsurvivors (p = 0.001).

CONCLUSIONS

The AARC-ACLF score is easy to use, dynamic and reliable, and superior to the existing prediction models. It can reliably predict the need for interventions, such as liver transplant, within the first week.

Human serum attenuates the activity of protease inhibitors toward wild-type and mutant human immunodeficiency virus

The potency of therapeutic regimens containing human immunodeficiency virus (HIV) protease inhibitors is related to the ability to maintain concentrations of drug in the plasma of patients that are sufficient for blocking viral replication. The estimation of concentrations required for in vivo activity using in vitro assays is complicated by the fact that extensive binding of many protease inhibitors to serum proteins attenuates their antiviral potency. To provide insight into the relative in vivo potency of current protease inhibitors, we assayed their in vitro activity against wild-type and mutant HIV in the presence of human serum (HS). Using this assay, ABT-378, a new protease inhibitor with trough levels in humans far in excess of the EC50 in the presence of 50% HS, was identified. The antiviral activity of ABT-378 was only modestly attenuated by HS, in contrast to ritonavir, saquinavir, and nelfinavir. Examination of the effect of individual serum components suggested that the activity of ABT-378 is affected predominantly by binding to alpha1-acid glycoprotein (AGP) while the activity of ritonavir is modulated by both AGP and albumin. The method described here may provide insight into the in vivo potency of protease inhibitors and be useful for the preclinical evaluation and selection of new protease inhibitors for clinical studies.

Chitosan based water-resistant adhesive. Analogy to mussel glue

Using analogies from nature, we investigated the possibility that tyrosinase-catalyzed reactions of 3,4-dihydroxyphenethylamine (dopamine) could confer water-resistant adhesive properties to semidilute solutions of the polysaccharide chitosan. Rheological measurements showed that the tyrosinase-catalyzed, and subsequent uncatalyzed, reactions lead to substantial increases in the viscosity of the chitosan solutions. Samples from these high-viscosity modified-chitosans were spread onto dry glass slides, the slides were lapped and clipped together either in air or after being submerged in water, and the bound slides were held under water for several hours. Adhesive shear strengths of over 400 kPa were observed for these modified chitosan samples, while control chitosan solutions conferred no adhesive strength (i.e., the glass slides separated in the absence of measurable forces). High viscosities and water-resistant adhesive strengths were also observed when semidilute chitosan solutions were treated with the known cross-linking agent, glutaraldehyde. Further studies indicate a relationship between the increased viscosities and water-resistant adhesion. These results demonstrate that the renewable biopolymer chitosan can be converted into a water-resistant adhesive.

Enzymatic grafting of a natural product onto chitosan to confer water solubility under basic conditions

Chitosan is a natural biopolymer whose rich amine functionality confers water solubility at low pH. At higher pH's (greater than 6. 5), the amines are deprotonated and chitosan is insoluble. To attain water solubility under basic conditions we enzymatically grafted the hydrophilic compound chlorogenic acid onto chitosan. Despite its name, chlorogenic acid is a nonchlorinated phenolic natural product that has carboxylic acid and hydroxyl functionality. The enzyme in this study was tyrosinase, which converts a wide range of phenolic substrates into electrophilic o-quinones. The o-quinones are freely diffusible and can undergo reaction with the nucleophilic amino groups of chitosan. Using slightly acidic conditions (pH = 6), it was possible to modify chitosan under homogeneous conditions. When the amount of chlorogenic acid used in the modification reaction exceeded 30% relative to chitosan's amino groups, the modified chitosan was observed to be soluble under both acidic and basic conditions, and to have a pH window of insolubility at near neutral pH. 1H NMR spectra confirmed that chitosan was chemically modified, although the degree of modification was low. Copyright 1999 John Wiley & Sons, Inc.

Enzymatic grafting of hexyloxyphenol onto chitosan to alter surface and rheological properties

An enzymatic method to graft hexyloxyphenol onto the biopolymer chitosan was studied. The method employs tyrosinase to convert the phenol into a reactive o-quinone, which undergoes subsequent nonenzymatic reaction with chitosan. Reactions were conducted under heterogeneous conditions using chitosan films and also under homogeneous conditions using aqueous methanolic mixtures capable of dissolving both hexyloxyphenol and chitosan. Tyrosinase was shown to catalyze the oxidation of hexyloxyphenol in such aqueous methanolic solutions. Chemical evidence for covalent grafting onto chitosan was provided by three independent spectroscopic approaches. Specifically, enzymatic modification resulted in (1) the appearance of broad absorbance in the 350-nm region of the UV/vis spectra for chitosan films; (2) changes in the NH bending and stretching regions of chitosan's IR spectra; and (3) a base-soluble material with (1)H-NMR signals characteristic of both chitosan and the alkyl groups of hexyloxyphenol. Hexyloxyphenol modification resulted in dramatic changes in chitosan's functional properties. On the basis of contact angle measurements, heterogeneous modification of a chitosan film yielded a hydrophobic surface. Homogeneously modified chitosan offered rheological properties characteristic of associating water-soluble polymers.

Turbulent nature of refractive-index variations in biological tissue

Phase-contrast microscopy shows that the structure of the refractive-index inhomogeneities in a variety of mammalian tissues resembles that of frozen turbulence. Viewed over a range of scales, the spectrum of index variations exhibits a power-law behavior for spatial frequencies spanning at least a decade (0.5-5 microm(-1)) and has an outer scale in the range of 4-10 microm, above which correlations are no longer seen. The observed structure function fits the classical Kolmogorov model of turbulence. These observations are fundamental to understanding light propagation in tissue and may provide clues about how tissues develop and organize.

Reproductive toxicity of lead, cadmium, and phthalate exposure in men

Environmental toxicants viz lead or cadmium and phthalate esters (di(2-ethylhexyl) phthalate [DEHP], dibutyl phthalate [DBP], and diethyl phthalate [DEP]) widely found in different environmental strata are linked to deteriorating male reproductive health. The objective was to assess the relationships between the seminal lead, cadmium, and phthalate (DEHP, DBP, DEP) concentrations at environmental level and serum hormone levels and semen quality in non-occupationally exposed men and specify the effect of individual and combined exposure of toxicants on semen quality. A study of 60 male partners of couples attending the Andrology Laboratory of the Reproductive Biology Department, All India Institute of Medical Sciences (AIIMS), New Delhi, India for semen analysis to assess their inability to achieve a pregnancy was selected for the study. The results of univariate and stepwise multiple regression analysis in the unadjusted model showed a significant correlation between lead or cadmium and phthalates DEHP/DBP/DEP and sperm motility, sperm concentration, and DNA damage. After adjusting for potential confounders, an association with lead or DEHP was only observed. The present data shows that lead (Pb) or cadmium (Cd) or phthalates might independently contribute to decline in semen quality and induce DNA damage. Phthalates might influence reproductive hormone testosterone. These findings are significant in light of the fact that men are exposed to a volley of chemicals; however, due to the small sample size, our finding needs to be confirmed in a larger population.

Self-reported suicidal ideation in adolescent psychiatric inpatients

In an investigation of the psychosocial correlates of suicidal ideation in adolescent inpatients, the Beck Scale for Suicide Ideation (BSI) was administered to 108 inpatients between 12 and 17 years of age who were diagnosed with mixed psychiatric disorders. A series of multiple regression analyses that controlled for gender, ethnicity, age, diagnosis of a mood disorder, and a history of a past suicide attempt were then used to examine the relationships of the Beck Depression Inventory, Anxiety Inventory, and Hopelessness Scale (BHS) with the BSI. Regardless of the series, the BHS contributed unique variance to the explanation of the BSI scores. The results are discussed as supporting the use of the BSI with adolescent inpatients and indicating that hopelessness is related to suicidal ideation when depression is controlled for.

Synthesis of platinum nanoparticles using seaweed Padina gymnospora and their catalytic activity as PVP/PtNPs nanocomposite towards biological applications

In the recent years, synthesis of nanomaterials using seaweeds and their diverse applications is escalating research in modern era. Among the noble metals, platinum nanoparticles (PtNPs) are of great importance owing to their catalytic property and less toxicity. The significance of this work is a simple one-step synthesis of PtNPs using aqueous extract of Indian brown seaweed Padina gymnospora and their catalytic activity with a polymer Polyvinylpyrrolidone (PVP) as PVP/PtNPs nanocomposite towards antimicrobial, haemolytic, cytotoxic (Artemia salina) and antioxidant properties. Fourier Transform Infrared (FT-IR) spectrum results showed diversified functional groups (biomoeities such as carbohydrates and proteins) present in the seaweed extract is responsible for the reduction of platinum ions (Pt+) to PtNPs. The seaweed mediated PtNPs was characterized by UV-vis spectrophotometer, X-ray diffraction (XRD) pattern, Field Emission Scanning Electron Microscopy (FESEM) equipped with Energy Dispersive X-ray (EDX) spectroscopy and High Resolution Transmission Electron Microscopy (HRTEM) analysis. The synthesized PtNPs was found to be truncated octahedral in shape with the range of 5-50nm. Crystalline nature of the nanoparticles was evidenced by Selected Area Electron Diffraction (SAED) pattern with bright circular spots corresponding to (111), (200), (220) and (311) Bragg's reflection planes. The size of the PtNPs was further evidenced by Dynamic Light Scattering (DLS) analysis and it is originate to be stable at -22.5mV through Zeta Potential (ZP) analysis. The present study shows that the catalytic behavior of PtNPs as polymer/metal nanocomposite (PVP/PtNPs) preparation for an antibacterial activity against seven disease causing pathogenic bacterial strains with the maximum activity against Escherichia coli (15.6mm) followed by Lactococcus lactis (14.8mm) and Klebsiella pneumoniae (14.4mm). But no haemolytic activity was seen at their effective bactericidal concentration, whereas increase in the haeomyltic activity was seen only in higher concentrations (600, 900 and 1200μgmL-1). On the other hand, PVP/PtNPs nanocomposite has shown cytotoxic activity at 100±4μgmL-1 (LC50) against Artemia salina nauplii. Furthermore, PVP/PtNPs nanocomposite showed an enhanced scavenging activity against 2,2-diphenyl-1-picrylhydrazyl (DPPH), superoxide, nitric oxide and hydroxyl radicals.

Hepatoprotective activity of Trianthema portulacastrum L. against paracetamol and thioacetamide intoxication in albino rats

The ethanolic extract of Trianthema portulacastrum L. (Aizoaceae) showed a significant dose dependent (100 mg, 200 mg/kg p.o. 10x) protective effect against paracetamol and thioacetamide induced hepatotoxicity in albino rats. The degree of protection was measured by using biochemical parameters like serum glutamate oxaloacetate transaminase (SGOT), serum glutamate pyruvate transaminase (SGPT), alkaline phosphatase (ALP), bilirubin (BRN), and total protein (TP). The plant extract completely prevented the toxic effects of paracetamol (acetaminophen) and thioacetamide on the above serum parameters. A significant hepatoprotective activity of the ethanolic extracts of Trianthema portulacastrum L. was reported.

Zinc deficiency affects cell cycle and deoxythymidine kinase gene expression in HUT-78 cells

Although zinc is known to be involved in cell proliferation and DNA synthesis, the mechanism by which zinc may regulate these processes is not understood. We have studied the role of zinc on cell proliferation and gene expression of a DNA synthesizing enzyme, deoxythymidine kinase (TK), in a T helper human malignant lymphoblastoid cell line (HUT-78). In zinc-deficient and zinc-sufficient media, the cell doubling time (mean +/- SD) of HUT-78 was 59 +/- 8 hours and 32.6 +/- 6 hours, respectively. The effect of zinc was T cell specific, inasmuch as the cell growth of another T malignant lymphoblastoid cell line, MOLT-3 (immature T cells), was not affected by zinc deficiency. Iron, copper, or manganese did not completely correct the cell growth of zinc-deficient HUT-78 cells. TK activity and the relative accumulation of TK-mRNA were significantly decreased in zinc-deficient cells during the G1 phase of cell cycle in comparison with zinc-sufficient cells. Nuclear run-on experiments and actinomycin-D studies showed that the transcription of TK-mRNA was affected adversely by zinc deficiency. Cell cycle studies showed that more zinc-deficient cells remained in S phase and did not undergo mitosis in comparison with zinc-sufficient cells. In conclusion, our data show that zinc is a T cell-specific growth factor and that a decreased gene expression of DNA-synthesizing enzyme TK in zinc-deficient HUT-78 cells in G1 phase affected adversely the DNA synthesis in S phase and delayed cell cycle.

Malignant transformation of mesenchymal hamartoma of the liver: case report and review of the literature

Here the first case in the literature of both mesenchymal hamartoma and malignant mesenchymoma occurring in a 6-year-old male child, at different times and at different sites in the liver, and also the possible malignant transformation of a mesenchymal hamartoma is reported. The tumor developed from a lesion in the right lobe that was overlooked initially during a left lateral segmentectomy at 18 months of age for a mesenchymal hamartoma. Malignant mesenchymoma is a rare and aggressive tumor. The origin of this tumor is not well understood. There has been no direct support to the hypothesis that malignant mesenchymoma may be the malignant counterpart of mesenchymal hamartoma. The authors provide clinical and histopathologic evidence in our case that suggests the possibility of malignant mesenchymoma arising from a mesenchymal hamartoma. This case emphasizes the need for complete removal of mesenchymal hamartoma and the need for long-term follow-up to detect multifocal lesion or malignant transformation.

Oncostatin-M stimulates tyrosine protein phosphorylation in parallel with the activation of p42MAPK/ERK-2 in Kaposi's cells. Evidence that this pathway is important in Kaposi cell growth

Oncostatin-M (OSM) is a potent mitogen for Kaposi's sarcoma (KS) cells. We studied signaling by the OSM receptor in three AIDS-related KS lines and show induction of tyrosine phosphorylation of 145-, 120-, 85-, and 42-kD substrates. The 42-kD substrate was identified as p42MAPK (mitogen-activated protein kinase), also known as ERK-2. This serine/threonine kinase relays mitogenic signals from receptor tyrosine protein kinases (TPKs) or receptor-associated TPKs to transcriptional activators. The OSM dose dependence for MAP kinase activation and induction of KS cell growth were almost identical, suggesting functional linkage. MAP kinase activation was dependent on tyrosine phosphorylation, and both OSM-induced MAP kinase activity and KS cell growth could be suppressed by TPK inhibitors, genistein and geldanomycin. OSM also stimulated tyrosine phosphorylation of similar substrates and MAP kinase activity in human vein endothelial cells. While it has been proposed that the OSM receptor may include the gp130 subunit of the IL-6 receptor and alpha-chain of leukemia inhibitory factor (LIF) receptor, neither LIF nor r.IL-6 induced tyrosine protein phosphorylation or p42MAPK activation in KS cells. However, r.IL-6 did stimulate tyrosine phosphorylation and p42MAPK activity in the human B cell line, AF-10, while OSM and LIF exerted no effects. Our results indicate that, although the OSM and IL-6 receptors share a common signaling pathway, this pathway is selectively activated by OSM in Kaposi's cells.

Plant cell biodegradation of a xenobiotic nitrate ester, nitroglycerin

The ability of plants to metabolize the xenobiotic nitrate ester, glycerol trinitrate (GTN, nitroglycerin), was examined using cultured plant cells and plant cell extracts. Intact cells rapidly degrade GTN with the initial formation of glycerol dinitrate (GDN) and the later formation of glycerol mononitrate (GMN). A material balance analysis of these intermediates indicates little, if any, formation of reduced, conjugated or cell-bound carbonaceous metabolites. Cell extracts were shown to be capable of degrading GTN with the simultaneous formation of GDN in stoichiometric amounts. The intermediates observed, and the timing of their appearance, are consistent with a sequential denitration pathway that has been reported for the microbial degradation of nitrate esters. The degradative activities of plant cells are only tenfold less than those reported for bacterial GTN degradation. These results suggests that plants may serve a direct degradative function for the phytoremediation of sites contaminated by organic nitrate esters.

Use of the Beck Anxiety Inventory with adolescent psychiatric outpatients

The Beck Anxiety Inventory was administered to 105 outpatients between 13 and 17 years old who were diagnosed with various types of psychiatric disorders. A principal factor analysis was performed, and two factors were found representing subjective and somatic symptoms of anxiety. The item compositions of these factors were comparable to those previously described for adolescent inpatients. The results are discussed as supporting the use of the inventory for evaluating self-reported anxiety in outpatient adolescents.

Denitration of glycerol trinitrate by resting cells and cell extracts of Bacillus thuringiensis/cereus and Enterobacter agglomerans

A number of microorganisms were selected from soil and sediment samples which were known to have been previously exposed to nitrate ester contaminants. The two most effective bacteria for transforming glycerol trinitrate (GTN) were identified as Bacillus thuringiensis/cereus and Enterobacter agglomerans. For both isolates, denitration activities were expressed constitutively and GTN was not required for induction. Dialysis of cell extracts from both isolates did not affect denitration, which indicates that dissociable and depletable cofactors are not required for denitration. With thin-layer chromatography and high-performance liquid chromatography, the denitration pathway for both isolates was shown to be a sequential denitration of GTN to glycerol dinitrate isomers, glycerol mononitrate isomers, and ultimately to glycerol. GTN was observed to be completely converted to glycerol during a long-term incubation of cell extracts.

Polyoxazoline-peptide adducts that retain antibody avidity

Synthetic polymers have long been used to modify various properties of proteins such as activity and solubility. Polyethylene glycol (PEG) has been widely used to form adducts with enzymes and antibodies. In this study, the polyoxazoline family of water-soluble polymers was used to synthesize adducts containing a synthetic peptide recognized by a monoclonal antibody (MAb) directed against human protein C (hPC). This is the first application of direct conjugation of unterminated or "living" polymer to a peptide. The avidity of the antibody for the various adducts was characterized with respect to size and hydrophilicity of methyl- and ethyl-substituted polyoxazoline polymers (POX). Avidity of the adducts was not found to be dependent upon the hydrophilicity and was slightly decreased due to polymer modification. The methyl-POX-peptide adducts were found to be highly water soluble, while the ethyl-POX-peptide adducts showed sporadic problems with aqueous solubility. Because the polymer-peptide adducts retained avidity for the antibody, polyoxazoline polymers may have potential application to protein-adduct chemistry.

Study of clinical, biochemical and immunological factors determining stability of disease in patients with generalized vitiligo undergoing melanocyte transplantation

BACKGROUND

Stability is considered the most important parameter before performing any melanocyte transplantation procedure in vitiligo; however, current criteria rely on the history given by the patients.

OBJECTIVE

This study was undertaken to determine the clinical, biochemical and immunological factors determining stability of disease in patients with generalized vitiligo to facilitate better patient selection for melanocyte transplantation and to understand immunological mechanisms for disease activity.

METHODS

Thirty-three patients with generalized vitiligo with < 10% body surface area involved were allocated to three clinical stability groups: Group 1 (stability > 3 months but < 1 year), Group 2 (≥ 1 year but < 2 years) and Group 3 (≥ 2 years). Melanocyte transplantation was done using suction blister epidermal grafting (SBEG) on a single patch. Blood was drawn for catalase estimation from all patients and from 10 healthy control subjects. A 3-mm punch biopsy was taken on the day of transplantation from the margin of the macule in the first five patients in each group for the immunohistochemistry of CD4, CD8, CD45RO, CD45RA and FoxP3. Those with ≥ 75% repigmentation at 6 months were labelled as responders.

RESULTS

The success rate was 0% in Group 1, 37·5% in Group 2 and 77·8% in Group 3. The difference in the success rate between the groups was statistically significant (P = 0·005). The median period of stability was significantly higher in the responders compared with that in the nonresponders (P = 0·001). Catalase levels were not significantly different between patients in the three groups of cases and in controls, or between responders and nonresponders. Lesional CD8 cells were significantly higher in Group 1 compared with Group 3. The percentages of CD8 and CD45RO cells were significantly higher in the nonresponders compared with the responders.

CONCLUSION

Along with clinical stability, the proportion of CD8 and CD45RO cells in skin biopsies might help to determine the stability of the disease and thereby predict the success of transplantation.

Optimal probe geometry for near-infrared spectroscopy of biological tissue

The results of this study clarify the influence of probe geometry on spectroscopic measurements obtained from the surface of a turbid biological tissue. We show that the transition between the measurement of the predominantly backward-propagating and the predominantly forward-propagating photon fluxes is marked by the separation between the source probe and the detector probes at which the dependence of the fluence on small changes in scattering coefficient vanishes. This is the probe separation at which a variable scattering background has the least influence on the measurement of optical absorption in turbid materials. Estimates of the optimum probe spacing for typical values of absorption and scattering coefficients of soft tissue in the near-infrared spectral region (800-2500 nm) are derived from an analytical solution of the diffusion equation. The estimates were verified by Monte Carlo simulations and experiments on particle suspensions with optical properties similar to those of skin tissue.