Tinea capitis et barbae caused by Trichophyton tonsurans: A retrospective cohort study of an infection chain after shavings in barber shops

BACKGROUND

Tinea capitis is a highly contagious infectious disease caused by dermatophytes. In Central Europe, it is mainly caused by zoophilic dermatophytes, as, for example Microsporum (M) canis or Trichophyton (T) mentagrophytes and increasingly by anthropophilic fungi. T tonsurans was commonly related to the Tinea gladiatorum, where transmission occurred between infected persons or via contaminated floors.

OBJECTIVE

Reporting the transmission of this highly contagious dermatophyte for the first time via beard shaving and hairdressing in barber shops in Germany.

PATIENTS AND METHODS

18 young male patients developed tinea capitis and/or barbae shortly after shavings of the beard and/or hair in a barber shop. Native, cultural and molecular diagnostics as well as tissue biopsies and resistance tests were performed of skin and hair samples.

RESULTS

In all samples, T tonsurans could be identified. The medical history and the clinical picture suggest a transmission through contaminated hairdressing tools. The patients were treated with terbinafine or itraconazole in combination with or exclusively with topical antimycotics.

CONCLUSION

The transmission and a resulting increase in the incidence of infections with T tonsurans may be due to shavings with direct skin contact of insufficiently disinfected hairdressing tools. This path of infection has already been observed in Africa and is now being described for the first time in Germany. Knowledge of the pathogen and its transmission ways are essential to interrupt the chain of infection.

Optical coherence tomography of cutaneous lupus erythematosus correlates with histopathology

Diagnosis of cutaneous forms of lupus erythematosus (LE), including chronic discoid LE (CDLE) and subacute cutaneous LE (SCLE), is usually based on characteristic clinical and histopathological findings. We aimed to visualize morphological changes in lesions of cutaneous LE using optical coherence tomography (OCT), and to correlate the OCT findings with histopathology. Six patients with CDLE and five patients with SCLE were investigated. Prior to skin biopsy, OCT assessment was performed on previously marked lesions. The images of OCT and corresponding histology were evaluated side-by-side on the PC screen. The thickening and disruption of the entrance signal in OCT images correlated with the hyperkeratosis which was observed in the histological sections. Atrophy of the epidermis, which was demonstrated by histology, could also be detected in the OCT pictures showing a thinned layer below the entrance signals. On OCT, a patchy reduction of reflectivity was observed in the upper dermis corresponding to dense patchy, partly lichenoid, lymphocytic infiltrates and oedema of the upper dermis. Furthermore, OCT images displayed increased signal-free cavities which histopathologically corresponded to dilated vessels in the upper dermis. All OCT parameters studied significantly (P < 0.05) correlated with histopathological features as indicated by coefficients of correlation ranging from 0.55 to 0.94. OCT enables to demonstrate micromorphological changes in cutaneous LE which correlate with histopathological findings. Nevertheless, the current technique does not allow one to visualize definite diagnostic features of cutaneous LE. However, OCT may be a promising method for objective monitoring of LE activity and treatment effects over time in vivo

Electrochemotherapy in advanced skin tumors and cutaneous metastases - a retrospective multicenter analysis

BACKGROUND AND OBJECTIVES

Once classic treatments such as chemotherapy or radiation therapy have been exhausted, only few therapeutic options remain for extensive skin tumors or cutaneous metastases. In such cases, electrochemotherapy may be considered as alternative therapy.

PATIENTS AND METHODS

In this retrospective study, clinical features, treatment response, and adverse effects were evaluated in 56 patients treated with electrochemotherapy at six German dermatology departments.

RESULTS

The mean age of the patient cohort (14 men, 42 women) was 69.3 years. Included were 20 patients with skin metastasis of advanced malignant melanoma, 13 patients with breast cancer metastases, 15 patients with primary squamous cell carcinoma of the skin or cutaneous metastases of other carcinoma types, and 8 patients with cutaneous lymphoma or sarcoma. The overall response rate was 44.6% (10.7% complete response; 33.9% partial response). By contrast, 31 (55.4%) patients did not respond (12.5% had stable disease; 42.9%, tumor progression). Patients with melanoma and cutaneous lymphoma or sarcoma responded significantly better than those with carcinoma. Roughly one quarter of patients showed an improvement in tumor-related exudation, fetor, and chronic bleeding.

CONCLUSION

Showing only few adverse effects, electrochemotherapy was effective in about one half of the patients with advanced tumors. Treatment response appears to depend on the tumor entity.

Promotion of stem cell proliferation by vegetable peptone

OBJECTIVES

Technical limitations and evolution of therapeutic applications for cell culture-derived products have accelerated elimination of animal-derived constituents from such products to minimize inadvertent introduction of microbial contaminants, such as fungi, bacteria or viruses. The study described here was conducted to investigate the proliferative effect of vegetable peptone on adult stem cells in the absence of serum, and its possible mechanisms of action.

MATERIALS AND METHODS

Cell viability and proliferation were determined using the MTT assay and Click-iT EdU flow cytometry, respectively. In addition, changes in expression of cytokine genes were analysed using MILLIPLEX human cytokine enzyme-linked immunosorbent assay kit.

RESULTS

Viability of cord blood-derived mesenchymal stem cells (CB-MSC) and adipose tissue-derived stem cells (ADSC) increased significantly when treated with the peptone. In addition, median value of the group treated with peptone shifted to the right when compared to the untreated control group. Furthermore, quantitative analysis of the cytokines revealed that production of vascular endothelial growth factor (VEGF), transforming growth factor-beta1 (TGF-beta1), and interleukin-6 (IL-6) increased significantly in response to treatment with our vegetable peptone in both CB-MSCs and ADSCs.

CONCLUSIONS

Our findings revealed that the vegetable peptone promotes proliferation of CB-MSCs and ADSCs. In addition, results of this study suggest that induction of stem cell proliferation by vegetable peptone is likely to be related to its induction of VEGF, TGF-beta1, and IL-6 expression.

Does chemosensitivity-assay-directed therapy have an influence on the prognosis of patients with malignant melanoma stage IV? A retrospective study of 14 patients with malignant melanoma stage IV

OBJECTIVE

To evaluate the efficacy of chemosensitivity-testing directed chemotherapy in comparison with empirically chosen therapy regimens in patients with malignant melanoma stage IV.

PATIENTS AND METHODS

Retrospective study including 14 patients with histologically confirmed malignant melanoma and diagnosis of stage IV disease by routine diagnostic procedures. Patients in group A (n = 7) were treated according to their individual chemosensitivity testing results, whereas patients in group B (n = 7) received empirically chosen treatment regimens. Chemosensitivity testing was performed using a nonclonogenic ATP-TCA assay. For statistical analysis the Kaplan-Meier method was used to calculate survival curves. The log-rank test was performed to compare the overall survival according to treatment group, LDH level in serum and AJCC-category. To compare the distribution of sex, LDH level in serum and AJCC-category between the treatment groups, the Fisher exact test was used.

RESULTS

The median overall survival of group A exceeded the median overall survival of group B by 8 versus 3 months, respectively with a median overall survival of 5 months for the whole study population. LDH level in serum at study entry showed a strong correlation with overall survival, with normal LDH levels leading to a statistically significant longer survival (p = 0.006 for the log-rank test, respectively). Moreover, stage AJCC M1a/b yielded to a better prognosis compared with stage AJCC M1c (log-rank test p = 0.066; not statistically significant).

CONCLUSION

Chemosensitivity-assay directed therapy might be a useful tool in determining the optimized chemotherapeutic drug or drug combination in the individual patient and might contribute to a better prognosis in patients with metastatic melanoma stage IV.

Increased expression of TGF-beta/Smad proteins in basal cell carcinoma

BACKGROUND

Basal cell carcinoma (BCC) is the most common cancer in humans placing a significant burden on healthcare services worldwide. There is an increasing evidence that the development of cutaneous epithelial tumours is pathogenetically linked to dysregulations of the transforming growth factor beta (TGF-beta) and its signalling molecules, the Smads.

OBJECTIVE

In the present study we aimed to investigate the mRNA as well as protein expression of TGF-beta/ Smad signalling proteins in patients with BCC and healthy controls.

METHODS

In this prospective pilot study, 24 patients with BCC were recruited. Punch biopsies were harvested from the centre of the tumour (lesional) as well as an adjacent healthy skin site (non-lesional controls). In addition to the specimens of BCC patients, skin samples (healthy controls) were obtained from subjects who had no history of skin cancer (n = 25). Real-time RT-PCR as well as immunohistochemistry was performed. -

RESULTS

The mRNA levels of TGF-b/Smad transducers observed in healthy controls did not significantly differ from TGF-beta/Smad levels observed in non-lesional skin of BCCs patients (P > 0.05). RT-PCR revealed significant mRNA overexpression of TGF-beta1, Smad3, and Smad7 in BCCs as compared to non-lesional skin (P < 0.05). TGF-beta1 mRNA expression significantly correlated with Smad3 (r = 0.60; P < 0.05) and Smad7 (r = 0.76; P < 0.05) levels. Immunohistochemistry demonstrated marked protein overexpression of Smad3 in tumour tissue as compared to non-lesional skin.

CONCLUSIONS

Our data suggest a possible role of TGF-beta/Smad signalling in the pathogenesis of BCC.

Susceptibility of various oral bacteria to antimicrobial peptides and to phagocytosis by neutrophils

BACKGROUND AND OBJECTIVE

The aim of this study was to compare the susceptibility of nonperiodontopathic and periodontopathic bacteria to major defense mechanisms for bacterial clearance in gingival sulcus.

MATERIAL AND METHODS

Twenty strains of 13 oral bacterial species were studied for their susceptibility to phagocytosis by human neutrophils and to the antimicrobial peptides LL-37 and human beta defensin-3. The minimum inhibitory concentrations of LL-37 and human beta defensin-3 were determined by a liquid dilution assay, and susceptibility to phagocytosis was examined by a flow cytometric phagocytosis assay.

RESULTS

The minimum inhibitory concentrations of LL-37 and human beta defensin-3 varied greatly, depending on the strain and species. Although a significant difference between the non- and periodontopathic groups was not observed, the red-complex bacteria were more resistant to LL-37 than the others (p=0.004). The susceptibility of oral bacteria to phagocytosis was quite variable, depending on the species but not on the strains. The periodontopathic bacteria, especially Actinobacillus actinomycetemcomitans and the red-complex triad, were more resistant to phagocytosis than were the nonperiodontopathic bacteria (p=0.0003). In addition, bacteria resistant both to antimicrobial peptides and to phagocytosis were more common in the periodontopathic group.

CONCLUSION

Our results indicate that immune evasion may contribute to the pathogenicity of some periodontopathic bacteria.

1% pimecrolimus, 0.005% calcipotriol, and 0.1% betamethasone in the treatment of intertriginous psoriasis: a double-blind, randomized controlled study

OBJECTIVE

During the last decades, management of intertriginous psoriasis (IP) has been unsatisfactory because of the adverse effects associated with long-term corticosteroid application and the lack of alternatives. Recently, both pimecrolimus and tacrolimus have been investigated for this indication and shown to be safe and effective. So far, to our knowledge, a comparison of one of these drugs with standard regimens for IP has not been performed.

DESIGN

A single-center, 4-week, double-blind, randomized, vehicle-controlled comparison study to assess the safety and efficacy of 1% pimecrolimus, 0.005% calcipotriol, and 0.1% betamethasone valerate in the treatment of IP.

SETTING

Dermatologic hospital at Ruhr University of Bochum.

PATIENTS

Eighty adults with IP.

INTERVENTIONS

Treatment of IP with 1% pimecrolimus, 0.005% calcipotriol, 0.1% betamethasone, or the vehicle once daily for 28 days.

MAIN OUTCOME MEASURES

Mean reduction of the Modified Psoriasis Area and Severity Index (M-PASI) score after 28 days of treatment was considered the primary outcome measure, which was analyzed on an intention-to-treat basis. The secondary outcome was a visual analog scale score for itching.

RESULTS

After 4 weeks of treatment, the 3 active compounds and the vehicle resulted in a significant decrease in mean M-PASI score (86.4% for 0.1% betamethasone, 62.4% for 0.005% calcipotriol, 39.7% for 1% pimecrolimus, and 21.1% for vehicle). The 0.1% betamethasone was significantly more effective than 1% pimecrolimus during the study period (P<.05). No significant difference was found between 0.005% calcipotriol and 0.1% betamethasone and between 0.005% calcipotriol and 1% pimecrolimus. The visual analog scale score for pruritus decreased by 78% for 0.1% betamethasone, 57% for 0.005% calcipotriol, 35% for 1% pimecrolimus, and 43% for the vehicle, again demonstrating a clear advantage for the corticosteroid (P<.05).

CONCLUSIONS

The 1% pimecrolimus was shown to be less potent than 0.1% betamethasone in the treatment of IP. Considering the adverse-effect profile of long-term application of corticosteroids, occasional or intermittent rescue therapy with short-term topical corticosteroids and maintenance with a less potent agent, such as 1% pimecrolimus or 0.005% calcipotriol, might be appropriate for patients with IP in general practice.

Ultraviolet A1 phototherapy decreases inhibitory SMAD7 gene expression in localized scleroderma

Localized scleroderma (LS) is a connective skin disease with marked sclerosis of the skin as the most prominent feature. Transforming growth factor beta (TGF-beta) plays a central role in the pathogenesis of sclerotic skin diseases. Recently, special attention was contributed to a family of transcription factor proteins involved in TGF-beta signal transduction from cell surface to the nucleus, the so-called SMADs. Ultraviolet (UV) irradiation has been reported to alter TGF-beta/SMAD pathway in human skin. We sought to investigate the effects of UVA1 on the gene and protein expressions of the TGF-beta/SMAD pathway in LS. UVA1 phototherapy was performed in eight LS patients five times weekly for 8 weeks resulting in a total of 40 treatment sessions (single dose 50 J/cm(2), cumulative dose 2,000 J/cm(2)). TGF-beta1, SMAD3, SMAD4, and SMAD7 mRNA expressions were determined by semiquantitative real-time reverse transcription polymerase chain reaction in lesional and unaffected skin of patients with LS. Additionally, immunohistochemical staining was performed in lesional skin before and after irradiation. Skin status markedly improved in all patients, resulting in a significant reduction of the clinical score from baseline to the end of treatment. Inhibitory SMAD7 mRNA was significantly higher in lesional skin as compared to unaffected skin, and significantly decreased after UVA1 phototherapy. In contrast, SMAD7 mRNA levels remained unchanged in irradiated, healthy skin after UVA1. Both TGF-beta and SMAD3 mRNA levels decreased after UVA1, whereas SMAD4 mRNA increased. However, changes in TGF-beta, SMAD3, and SMAD4 mRNA after UVA1 did not reach statistical significance. Immunohistochemical investigation did not reveal significant changes in the protein expression of SMADs after UVA1. Similar to scleroderma, SMAD7-mediated negative regulation seems to be impaired in LS. UVA1 phototherapy demonstrated the alteration of SMAD7 gene expression in LS, as SMAD7 mRNA levels normalized after UVA1. The pathogenetic relevance of SMAD7 levels with respect to clinical improvement needs further investigation.

Cytokine mRNA expression in basal cell carcinoma

There is evidence that cytokines (CKs) play a significant role in the development and/or progression of skin cancer. The aim of the present study was to investigate the mRNA expression of tumour necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6), and IL-8 in biopsy specimens of basal cell carcinoma (BCC), and to compare the results with the mRNA levels of non-lesional skin of BCC patients and healthy subjects. Skin samples were obtained from 22 patients with BCC (lesional, non-lesional) and 25 healthy subjects (controls). Routine histology and real-time RT-PCR was performed. Histological examination revealed 12 nodular BCCs and 10 superficial BCCs. The mRNA levels of CKs observed in healthy controls did not significantly (P > 0.05) differ from non-lesional CK levels of BCCs patients. However, IL-6 and IL-8 levels of lesional skin were significantly (P < 0.05) higher than the CK levels observed in non-lesional skin and controls, respectively. mRNA expression of IL-6 and IL-8 showed a significant positive correlation (r = 0.51; P < 0.05). There was no significant (P > 0.05) difference between lesional mRNA levels of TNF-alpha and those levels observed in non-lesional skin and controls. The mRNA expression of CKs found in nodular and superficial BCCs did not significantly differ (P > 0.05). BCC is associated with a significant increase of IL-6 and IL-8 expression. We have shown for the first time that upregulation of IL-6 mRNA significantly correlates with IL-8 overexpresssion. In accordance with previous studies our data suggest a role for IL-6 and IL-8 in the development and/or progression of BCC, since mRNA expression of both CKs are significantly increased in tumour tissue.

Ultraviolet A1-induced downregulation of human β -defensins and interleukin-6 and interleukin-8 correlates with clinical improvement in localized scleroderma

BACKGROUND

In previous studies, distinct immunological abnormalities have been reported in localized scleroderma (LS). Several pro-inflammatory cytokines have been demonstrated at increased levels in sera of patients with LS in parallel with disease activity. Human beta-defensins (hBDs) are peptides with antimicrobial activity, but have been also shown to be implicated in tissue injury, scarring and wound healing. hBD expression in LS, a condition resembling pathological scarring due to excessive stimulation of matrix synthesis and fibroblast activation, has so far not been investigated. Ultraviolet (UV) A1 phototherapy, the most recent advance in the treatment of LS, targets T-cell dermal inflammatory infiltrates via induction of various cytokines and soluble factors besides well-known effects on collagen metabolism.

OBJECTIVES

We sought to investigate the effects of UVA1 on the expression and modulation of hBDs and several pro-inflammatory cytokines in LS.

METHODS

UVA1 phototherapy was performed five times weekly for 8 weeks resulting in a total of 40 treatment sessions (single dose 20 J cm2, cumulative dose 800 J cm2). hBD-1, hBD-2 and hBD-3 mRNA as well as tumour necrosis factor-alpha, transforming growth factor-beta, interleukin (IL) -2, IL-4, IL-6 and IL-8 mRNA expression were determined by quantitative real-time reverse transcription-polymerase chain reaction in lesional and unaffected skin of patients with LS.

RESULTS

Skin status markedly improved in all 14 patients, resulting in a significant reduction of the clinical score from baseline to the end of treatment. hBD-1, hBD-2 and hBD-3 mRNA levels were higher in lesional skin compared with unaffected skin and skin from healthy volunteers. Following UVA1 phototherapy, hBD-1 mRNA decreased in lesional, but not in unaffected skin. hBD-3 mRNA levels significantly decreased after UVA1 in lesional skin, whereas an increase of hBD-3 was observed in unaffected skin. IL-6 and IL-8 mRNA levels were significantly elevated in lesional skin and significantly decreased after UVA1 irradiation, whereas mRNA for both cytokines remained unchanged in irradiated unaffected skin. The decrease of hBD-1, hBD-3, IL-6 and IL-8 mRNA paralleled the extent of disease and response to UVA1 phototherapy.

CONCLUSIONS

hBDs and IL-6 and IL-8, cytokines with pivotal importance in sclerotic skin diseases, are downregulated by UVA1 in the lesional skin of patients with LS. Their pathogenetic relevance with respect to clinical improvement needs further investigation.

A randomised controlled trial on photo(chemo)therapy of subacute purigo

BACKGROUND

Psoralen ultraviolet A (PUVA) is the standard photo(chemo)therapeutic regimen for patients suffering from subacute prurigo (SP).

HYPOTHESIS

Regarding efficacy, bath PUVA is not superior to medium-dose ultraviolet-A1 (MD-UVA1) and narrowband ultraviolet-B (NB-UVB), which may be considered the new photo(chemo)therapeutic options for SP.

METHODS

We performed a prospective randomised, controlled, three-arm photo(chemo)therapeutic study. Patients suffering from histopathologically proven SP with a clinical score (PIP score; papules, infiltration and pruritus) of at least 5 points were enrolled into the study. Treatment with bath PUVA was performed 4 times weekly and MD-UVA1 and NB-UVB 5 times weekly. Photo(chemo)therapy was administered over a 4-week period. Outcome measure was the severity of SP investigated by means of the PIP score after 4 weeks of therapy.

RESULTS

In total, 33 patients with SP were randomly allocated to photo(chemo)therapy. Bath PUVA (n = 9), MD-UVA1 (n = 11) and NB-UVB (n = 13) resulted in a significant reduction of the baseline PIP score as assessed on the basis of intention-to-treat (ITT) analysis (P = 0.003). However, ITT analysis revealed significantly higher PIP score reduction in patients who were treated with bath PUVA and MD-UVA1 compared with NB-UVB (P < 0.01, 95% CI 1.1-3.63 and P < 0.05, 95% CI 0.42-2.70, respectively).

CONCLUSIONS

Photo(chemo)therapy, including bath PUVA, MD-UVA1 and NB-UVB, appears to be an effective and safe treatment option for patients suffering from SP. UVA1 and particularly PUVA seem superior to NB-UVB in the management of SP.

A randomized controlled study of low-dose UVA1, medium-dose UVA1, and narrowband UVB phototherapy in the treatment of localized scleroderma

BACKGROUND

In previous trials, UV therapy has been demonstrated to be effective in the treatment of localized scleroderma (LS). To date, a randomized comparison study to evaluate the efficacy and safety of different, commonly used phototherapeutic modalities in LS is still outstanding.

OBJECTIVE

The aim of this study was to compare the safety and efficacy of low-dose (LD) UVA1, medium-dose (MD) UVA1, and narrowband (NB) UVB phototherapy in the treatment of LS.

METHODS

Sixty four patients with LS were consecutively included in a prospective, open, randomized controlled 3-arm study. Severity of LS was determined by means of a clinical score, and clinical improvement was also monitored by histopathologic analysis and 20-MHz ultrasound.

RESULTS

A total of 27 patients were treated with LD UVA1 (20 J/cm2), 18 patients received MD UVA1 (50 J/cm2), and 19 patients were treated with NB UVB dependent on their skin type. Phototherapy was performed 5 times weekly for 8 weeks. Two of the 64 patients included in this trial discontinued therapy. Skin status significantly improved in all patients who finished the treatment protocol, resulting in a reduction of the clinical score in all groups (LD UVA1, 7.6-5.0 [P < .001, 95% confidence interval 1.6-3.4]; MD UVA1, 11.1-6.6 [P < .001, 95% confidence interval 2.5-6.2]; NB UVB, 7.3-4.9 [P < .001, 95% confidence interval 1.6-3.2]). The reduction of the score was accompanied by an improvement of the visual analog scale for itching and tightness, histologic score, and 20-MHz ultrasound. MD UVA1 was significantly more effective than NB UVB (P < .05). There were no significant differences between LD UVA1 and NB UVB and the former and MD UVA1 (P > .05).

LIMITATIONS

We had a relatively small study sample and nonblinded assessment of primary outcome.

CONCLUSION

Phototherapy, as previously reported in several noncontrolled trials, is an effective therapeutic option in LS, with a favorable risk/benefit ratio. UVA1 phototherapy should be considered among the first approaches in the management of LS.

A study of methods to reduce groundwater contamination around the Kimpo landfill in Korea

Four different methods were studied to reduce the groundwater contamination around the Kimpo landfill in Korea by leakage of a leachate. The hydraulic parameters were measured for this study and then the groundwater flow and contaminant transport systems around the Kimpo landfill were simulated with MODFLOW and MT3D models. Both the method of establishing 5 sets of Radial Collector Well Laterals (RCWLs) within the landfill and a method utilizing the wells for dewatering condensed water brought about a 70% leachate elimination efficiency. Their construction costs were cheap, and the maximum concentrations of chloride and phenol in the leachate effluent were high. Meanwhile, a method establishing an interception wall to the 2nd layer at the cirumference of the landfill and 22 sets of RCWLs within it brought about a 92% leachate elimination efficiency. Its construction cost was expensive, and the maximum concentrations of chloride and phenol in the leachate effluent were low. A method of establishing an interception wall to the 3rd layer and 40 sets of RCWLs brought about a 97% leachate elimination efficiency. Its construction cost was the most expensive, and the maximum concentrations of chloride and phenol were low. Conclusively, a method of establishing 22 sets of RCWLs was evaluated as the most stable and economical option to reduce groundwater contamination concentration below drinking water standard.

The reductive metabolism of nitric oxide in hepatocytes: possible interaction with thiols

Nitric oxide (NO) is both an endogenously generated species and the active species released from a variety of important drugs. Due to its endogenous generation and use as a therapeutic agent, the metabolism and fate of NO is of interest and concern. To date, most attention regarding the metabolism and fate of NO has been paid to its oxidized metabolites. Due to the reducing environment of cells, we considered that NO may also undergo reductive metabolism as well. Therefore, we have examined the reductive metabolism of NO by hepatocytes. Generation of nitrous oxide (N(2)O) was used as an indication of NO reduction. Indeed, we observed that NO could be reduced to N(2)O by the cytosolic fraction of hepatocytes. The N(2)O production was partially inhibited by the thiol modifying agent, N-ethylmaleimide and thiol consumption was observed during N(2)O formation. Thus, our results indicate that NO reduction is feasible and likely occurs via a thiol-dependent process.

Potentiation of cholecystokinin and secretin-induced pancreatic exocrine secretion by endogenous insulin in humans

To investigate the effects of endogenous insulin on pancreatic exocrine secretion in humans, we evaluated the pure pancreatic juice obtained by endoscopic cannulation of the main pancreatic duct in 21 healthy subjects (14 men and seven women). Samples of pancreatic juices were collected after intravenous injection of either glucose (50%, 40 ml), secretin (0.25 CU/kg), and cholecystokinin-8 (CCK) (40 ng/kg), or a combination of glucose, secretin, and CCK in six 5-min periods. The responses of plasma glucose, insulin, and C-peptide to intravenous administration of glucose were measured. After infusion of glucose, the plasma insulin and C-peptide levels were significantly increased and remained at high levels during 30-min experiments, intravenous administration of secretin and CCK resulted in significant increases of pancreatic secretion including volume, bicarbonate, and protein output. When glucose was simultaneously administered with secretin and CCK, pancreatic secretion was significantly increased, more than the effects achieved by the secretin and CCK. However, glucose alone did not increase basal pancreatic secretion. These observations suggest that endogenous insulin intensifies pancreatic secretion stimulated by secretin and CCK in humans.

Reaction between S-nitrosothiols and thiols: generation of nitroxyl (HNO) and subsequent chemistry

S-Nitrosothiols have been implicated to play key roles in a variety of physiological processes. The potential physiological importance of S-nitrosothiols prompted us to examine their reaction with thiols. We find that S-nitrosothiols can react with thiols to generate nitroxyl (HNO) and the corresponding disulfide. Further reaction of HNO with the remaining S-nitrosothiol and thiol results in the generation of other species including NO, sulfinamide, and hydroxylamine. Mechanisms are proposed that rationalize the observed products.

The role of thiols in the apparent activation of rat brain nitric oxide synthase (NOS)

The role of thiols on the activation and/or stabilization of rat brain nitric oxide synthase (NOS) has been investigated. It was found that thiols are not necessary for stabilizing or protecting the protein during purification but are required during enzyme turnover for maximum activity. In the complete absence of thiols but with added tetrahydrobiopterin, the enzyme retained a low basal activity. Thiol addition to a thiol-deplete preparation of the enzyme resulted in a 4 to 7-fold increase in activity when measured after 15 min. High concentrations of dihydropteridine reductase also caused an apparent activation of NOS and was capable of replacing thiols. The data presented is consistent with a cofactor role for thiols. The possibility that they serve as reducing agents for the regeneration of tetrahydrobiopterin from dihydrobiopterins is discussed.

The protective effect of tetrahydrobiopterin on the nitric oxide-mediated inhibition of purified nitric oxide synthase

The nitric oxide synthases (NOS) are a class of enzymes responsible for the generation of NO via an oxygen and NADPH dependent oxidation of the amino acid arginine. These enzymes are ironheme proteins which contain FAD and FMN and, enigmatically, require tetrahydrobiopterin (BH4). NOS has recently been shown to be subject to inhibition by its product, NO. Preliminary data by us indicate that a possible role for BH4 is to prevent and/or reverse the NO-mediated inhibition of NOS. The objective of this study was to elucidate the mechanism by which BH4 protects NOS against NO inhibition. Protection of NOS from NO inhibition was observed by both BH4 and the BH4 regeneration system, dihydropteridine reductase (DHPR)/NADH. NO, rather than an oxidation product, appears to be the inhibitory species. Protection by BH4 is not likely due to a simple chemical reaction between BH4 and NO or its oxidation product, NO2. The results are consistent with a protective mechanism by which BH4 may act as a nonstoichiometric reducing agent for a redox active enzyme component, such as the ironheme, to prevent NO ligation.

Aging of the human crystalline lens and anterior segment

Changes in the unaccommodated human crystalline lens were characterized as a function of subject age for 100 normal emmetropes over the age range 18-70 yr by Scheimpflug slit-lamp photography. With increasing age, the lens becomes thicker sagittally, but since the distance from the cornea to the posterior lens surface remains unchanged, this indicates that the center of lens mass moves anteriorly and the anterior chamber becomes shallower. Sagittal nuclear thickness is independent of age, but both anterior and posterior cortical thicknesses increase with age, shifting the location of the nucleus and the central sulcus in the anterior direction. The amount of light scattered by the lens at high angles, as represented by normalized and integrated lens densities from the digitized images, increases with increasing age in an exponential fashion. Similar relationships to age are observed for the major anterior zone of discontinuity (maximum density) and the central sulcus (minimum density). The relationships of these results to accommodation and presbyopia are discussed.