Treatment with synchronized radiofrequency and facial muscle stimulation: Histologic analysis of human skin for changes in collagen and elastin fibers

BACKGROUND

Skin's exposure to intrinsic and extrinsic factors causes age-related changes, leading to a lower amount of dermal collagen and elastin.

AIM

This study investigated the effects of a novel facial muscle stimulation technology combined with radiofrequency (RF) heating on dermal collagen and elastin content for the treatment of facial wrinkles and skin laxity.

METHODS

The active group subjects (N = 6) received four 20-min facial treatments with simultaneous RF and facial muscle stimulation, once weekly. The control subject (N = 1) was untreated. Skin biopsies obtained at baseline, 1-month and 3-month follow-up were evaluated histologically to determine collagen and elastin fibers content. A group of independent aestheticians evaluated facial skin appearance and wrinkle severity. Patient safety was followed.

RESULTS

In the active group, collagen-occupied area reached 11.91 ± 1.80 × 106 μm2 (+25.32%, p < 0.05) and 12.35 ± 1.44 × 105 μm2 (+30.00%, p < 0.05) at 1-month and 3-month follow-up visits. Elastin-occupied area at 1-month and 3-month follow-up was 1.64 ± 0.14 × 105 μm2 (+67.23%, p < 0.05), and 1.99 ± 0.21 × 105 μm2 (+102.80%, p < 0.05). In the control group, there was no significant difference (p > 0.05) in collagen and elastin fibers. Active group wrinkle scores decreased from 5 (moderate, class II) to 3 (mild, class I). All subjects, except the control, improved in appearance posttreatment. No adverse events or side effects occurred.

CONCLUSION

Decreased dermal collagen and elastin levels contributes to a gradual decline in skin elasticity, leading to facial wrinkles and unfirm skin. Study results showed noticeable improvement in facial appearance and increased dermal collagen and elastin content subsequent to simultaneous, noninvasive RF, and facial muscle stimulation treatments.

Laser-Assisted Prostaglandin Analogs in the Treatment of Hypopigmented Scars: A Systematic Review

Background

Hypopigmented scars are challenging to treat due to a lack of effective treatments and often transient results. Recent reports suggest that prostaglandin analog-induced hyperpigmentation may have favorable dermatological applications.

Objective

Analyze previous studies involving the use of prostaglandin analogs in the treatment of hypopigmented scars.

Methods

PubMed/Medline was queried through 10/01/2022 with the following search terms: (bimatoprost AND scar), (latanoprost AND scar), (travoprost AND scar), (prostaglandin analogs AND hypopigmented scars), (PGF2alpha AND hyperpigmentation), (prostaglandin analogs AND hyperpigmentation).

Results

In total, 88 unique studies were reviewed for eligibility. Five studies met inclusion criteria including two prospective, double-blinded, randomized (only one was placebo-controlled), one prospective case series, one retrospective chart review, and one case report; comprising a total of 87 patients. All five studies utilized topical prostaglandin analogs as an adjunctive treatment via laser-assisted delivery. While both, the placebo-controlled and non-placebo-controlled, trials reported more than 75 percent of patients experienced at least 50 percent or more (Grade 3 or higher) improvement, the retrospective study reported 100 percent of patients experienced at least 75 percent or more (Grade 4 or higher) improvement, measured as scar repigmentation. The prospective case series and the reported single case showed overall qualitative improvement in all patients measured as repigmentation of hypopigmented and depigmented scars.

Limitations

Different laser devices, parameters, treatment frequency, and follow-up timepoints.

Conclusion

All studies evaluated demonstrated favorable treatment outcomes with no reported adverse events. Additional, large randomized controlled trials are needed to fully assess the effectiveness and long-term safety of PGF2α agonists for hypopigmented scars.

Assessment of data intelligence algorithms in modeling daily reference evapotranspiration under input data limitation scenarios in semi-arid climatic condition

Crop evapotranspiration is essential for planning and designing an efficient irrigation system. The present investigation assessed the capability of four machine learning algorithms, namely, XGBoost linear regression (XGBoost Linear), XGBoost Ensemble Tree, Polynomial Regression (Polynomial Regr), and Isotonic Regression (Isotonic Regr) in modeling daily reference evapotranspiration (ET_o) at IARI, New Delhi. The models were developed considering full and limited dataset scenarios. The efficacy of the constructed models was assessed against the Penman-Monteith (PM56) model estimated daily ET_o. Results revealed the under full and limited dataset conditions, XGBoost Ensemble Tree gave the best results for daily ET_o modeling during the model training period, while in the testing period under scenarios S1(T_max) and S2 (T_max, and T_min), the Isotonic Regr models yielded superior results over other models. In addition, the XGBoost Ensemble Tree models outperformed others for the rest of the input data scenarios. The XGBoost Ensemble Tree algorithms reported the best values of correlation coefficient (r), mean absolute error (MAE), mean square error (MSE), root mean square error (RMSE), and mean absolute percentage error (MAPE). Thus, we recommend applying the XGBoost Ensemble Tree algorithm for precisely modeling daily ET_o in semi-arid climatic conditions.

Low rates of neurological abnormalities in patients with pigmentary mosaicism: A retrospective cohort study from a tertiary dermatology center

BACKGROUND

Pigmentary mosaicism (PM) is a descriptive term encompassing a range of hyper- and hypo-pigmented phenotypes in various patterns. Information from the neurology literature initially noted neurological abnormalities (NA) in up to 90% of children with PM. The dermatology literature suggests lower associated rates (15%-30%) of NA. Variations in terminology, inclusion criteria, and small population sizes makes interpreting existing PM literature complicated. We aimed to assess rates of NA in children presenting to dermatology with PM.

METHODS

We included patients <19 years, diagnosed with PM, nevus depigmentosus and/or segmental café au lait macules (CALM) seen in our dermatology department between 1 January 2006 and 31 December 2020. Patients with neurofibromatosis, McCune-Albright syndrome, and non-segmental CALM were excluded. Data collected included pigmentation, pattern, site(s) affected, presence of seizures, developmental delay, and microcephaly.

RESULTS

One hundred fifty patients were included (49.3% female), with a mean age at diagnosis of 4.27 years. Patterns of mosaicism were ascertained for 149 patients and included blaschkolinear (60/149, 40.3%), blocklike (79/149, 53.0%), or a combination of both patterns (10/149, 6.7%). Patients with a combination of patterns were more likely to have NA (p < .01). Overall, 22/149 (14.8%) had NA. Nine out of twenty-two patients with NA had hypopigmented blaschkolinear lesions (40.9%). Patients with ≥4 body sites affected were more likely to have NA (p < .01).

DISCUSSION

Overall, our population had low rates of NA in PM patients. A combination of blaschkolinear and blocklike patterns, or ≥4 body sites involved were associated with higher rates of NA.

Energy-based devices in the treatment of acne scars in skin of color

BACKGROUND

Acne scarring is disfiguring and psychologically taxing on patients. Many energy-based modalities have emerged and been studied for the treatment of acne scarring; however, there is a paucity of these studies in skin phototypes IV-VI.

OBJECTIVE

To review the medical literature and discuss the most significant studies regarding safety and efficacy of energy-based devices (ablative lasers, non-ablative lasers, and radiofrequency microneedling) in the treatment of ethnic skin (skin phototypes IV-VI).

METHODS

A literature search was conducted using the PubMed database and bibliographies of relevant articles.

RESULTS

Ablative and non-ablative lasers have proven to be effective for treatment of acne scars in ethnic skin. The risk of developing adverse effects such as post-inflammatory hyperpigmentation is contingent upon several factors including skin phototype, laser device, fluence, and moreso density settings. Non-ablative fractional lasers have been considered first line for the treatment of acne scars in skin of color due to their better safety profile; however, they are less efficacious and require more treatments compared to ablative lasers. Studies regarding efficacy and safety of radiofrequency microneedling for treatment of acne scarring in skin of color are limited, but are promising.

CONCLUSION

Ablative lasers, non-ablative lasers, and radiofrequency microneedling are all useful treatments for acne scarring in ethnic skin when appropriate settings are used. Further head-to-head studies are needed to evaluate their efficacy and safety in darker skin phototypes V-VI.

Evaluation of prognostic risk models for postoperative pulmonary complications in adult patients undergoing major abdominal surgery: a systematic review and international external validation cohort study

BACKGROUND

Stratifying risk of postoperative pulmonary complications after major abdominal surgery allows clinicians to modify risk through targeted interventions and enhanced monitoring. In this study, we aimed to identify and validate prognostic models against a new consensus definition of postoperative pulmonary complications.

METHODS

We did a systematic review and international external validation cohort study. The systematic review was done in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. We searched MEDLINE and Embase on March 1, 2020, for articles published in English that reported on risk prediction models for postoperative pulmonary complications following abdominal surgery. External validation of existing models was done within a prospective international cohort study of adult patients (≥18 years) undergoing major abdominal surgery. Data were collected between Jan 1, 2019, and April 30, 2019, in the UK, Ireland, and Australia. Discriminative ability and prognostic accuracy summary statistics were compared between models for the 30-day postoperative pulmonary complication rate as defined by the Standardised Endpoints in Perioperative Medicine Core Outcome Measures in Perioperative and Anaesthetic Care (StEP-COMPAC). Model performance was compared using the area under the receiver operating characteristic curve (AUROCC).

FINDINGS

In total, we identified 2903 records from our literature search; of which, 2514 (86·6%) unique records were screened, 121 (4·8%) of 2514 full texts were assessed for eligibility, and 29 unique prognostic models were identified. Nine (31·0%) of 29 models had score development reported only, 19 (65·5%) had undergone internal validation, and only four (13·8%) had been externally validated. Data to validate six eligible models were collected in the international external validation cohort study. Data from 11 591 patients were available, with an overall postoperative pulmonary complication rate of 7·8% (n=903). None of the six models showed good discrimination (defined as AUROCC ≥0·70) for identifying postoperative pulmonary complications, with the Assess Respiratory Risk in Surgical Patients in Catalonia score showing the best discrimination (AUROCC 0·700 [95% CI 0·683-0·717]).

INTERPRETATION

In the pre-COVID-19 pandemic data, variability in the risk of pulmonary complications (StEP-COMPAC definition) following major abdominal surgery was poorly described by existing prognostication tools. To improve surgical safety during the COVID-19 pandemic recovery and beyond, novel risk stratification tools are required.

FUNDING

British Journal of Surgery Society.

Utility of routine patch testing prior to surgical repair of pectus excavatum: A multidisciplinary experience via retrospective review at a single tertiary care center

BACKGROUND

The Nuss procedure is the only implant procedure in which routine, rather than selective, preoperative patch testing is recommended. This practice has recently been called into question.

OBJECTIVE

To evaluate an updated experience of pre-implant patch testing in patients undergoing the Nuss procedure.

METHODS

A retrospective chart review of Nuss procedures from 2012 through 2020.

RESULTS

Forty-five patients were identified for data collection. From 2012 to 2014, none of the 14 patients were patch tested. From 2015 to 2020, 26 of 31 (83.9%) were patch tested. Of those tested, only 2 had a positive patch test. A hypoallergenic titanium bar was inserted in each case. In total, there were zero bar reactions.

CONCLUSION

The risks of patch testing are extremely small and should be weighed against the serious implications of even one bar allergy when deciding on future guidelines.

Nail disease in neonatal abstinence syndrome

BACKGROUND/OBJECTIVES

Neonatal abstinence syndrome (NAS) incidence continues to rise in the United States due to increasing opioid use disorder in pregnancy. While cutaneous excoriations have been noted in NAS, there is a paucity of literature regarding abnormal nail findings in NAS.

METHODS

A retrospective, observational case series was conducted of twelve patients with NAS and abnormal nail findings who were admitted to the neonatal intensive care unit between January 1, 2018, and May 1, 2020.

RESULTS

Twelve neonates (10 male, 2 female, mean gestational age at birth 38.1 weeks) with NAS diagnosis and abnormal nail findings were identified between January 1, 2018, and May 1, 2020. NAS was diagnosed by elevated Modified Finnegan Neonatal Abstinence Syndrome Tool (M-FNAST) scores. All patients required pharmacologic treatment for NAS with seven (58.3%) requiring phenobarbital in addition to first-line morphine. Common nail findings included periungual erythema, yellow crusting, desquamation of the proximal and/or distal lateral nail folds and sheared distal nail edges. Two patients (16.7%) required antibiotic treatment for paronychia. Peak M-FNAST scores were positively correlated with number of abnormal nail findings (r = .58, P = .047).

CONCLUSIONS

Twelve neonates with severe NAS demonstrated similar nail abnormalities, likely secondary to NAS agitation and motor hyperactivity. Nail exams, therefore, are important in the setting of suspected or confirmed NAS to limit continued nail trauma and infection. Our findings also introduce an association between NAS severity and abnormal nail findings, which will require larger studies for further confirmation.

Darier sign in a teenager with primary cutaneous marginal zone lymphoma

Primary cutaneous marginal zone lymphoma (PCMZL) is a low-grade B-cell lymphoma that arises in the skin. An adolescent male presented with dermal nodules on the arms, legs, and back with a positive Darier sign, ultimately diagnosed as PCMZL. The nodules demonstrated a partial response to doxycycline in the setting of prior Lyme disease followed by a complete response to rituximab.

Proliferating pilomatricoma in a 9-year-old girl

Proliferating pilomatricoma is a rare, benign tumor of hair matrix origin that rarely occurs in children. We report the case of a 9-year-old girl with a rapidly growing, proliferating pilomatricoma located on the glabella. The lesion was embolized and surgically excised, with histopathological examination of the tissue confirming the diagnosis of proliferating pilomatricoma.

Dermatologic conditions in Down syndrome: A single-center retrospective chart review

BACKGROUND

Current literature addressing dermatologic conditions associated with Down syndrome is limited, with emphasis on rare skin conditions and lack of consensus on the incidence of more common disorders.

OBJECTIVE

We sought to evaluate dermatologic conditions in patients with Down syndrome diagnosed and managed by dermatologists.

METHODS

This was a retrospective analysis of 101 pediatric and adult patients with Down syndrome seen by the University of Massachusetts Dermatology Department between 2008 and 2018.

RESULTS

Folliculitis was the most common diagnosis overall (30.7%), followed by seborrheic dermatitis (26.7%) and hidradenitis suppurativa (22.8%). Eczematous dermatitis, alopecia areata, and xerosis were the most common diagnoses observed in children aged 0-12 years; hidradenitis suppurativa, folliculitis, and seborrheic dermatitis in adolescents aged 13-17 years; and folliculitis, seborrheic dermatitis, and xerosis in adults 18 years and older. Other notable diagnoses present overall included onychomycosis (9.9%) and psoriasis (8.9%). Malignant cutaneous tumors were present in two patients, specifically basal cell carcinoma and malignant melanoma in situ.

LIMITATIONS

This was a retrospective, single-institution study.

CONCLUSION

Dermatologic conditions in patients with Down syndrome vary by age but are most often adnexal and eczematous disorders. Trisomy of chromosome 21 and the resulting downstream effects, specifically on the immune system, may account for these findings.

Perioperative intravenous contrast administration and the incidence of acute kidney injury after major gastrointestinal surgery: prospective, multicentre cohort study

BACKGROUND

This study aimed to determine the impact of preoperative exposure to intravenous contrast for CT and the risk of developing postoperative acute kidney injury (AKI) in patients undergoing major gastrointestinal surgery.

METHODS

This prospective, multicentre cohort study included adults undergoing gastrointestinal resection, stoma reversal or liver resection. Both elective and emergency procedures were included. Preoperative exposure to intravenous contrast was defined as exposure to contrast administered for the purposes of CT up to 7 days before surgery. The primary endpoint was the rate of AKI within 7 days. Propensity score-matched models were adjusted for patient, disease and operative variables. In a sensitivity analysis, a propensity score-matched model explored the association between preoperative exposure to contrast and AKI in the first 48 h after surgery.

RESULTS

A total of 5378 patients were included across 173 centres. Overall, 1249 patients (23·2 per cent) received intravenous contrast. The overall rate of AKI within 7 days of surgery was 13·4 per cent (718 of 5378). In the propensity score-matched model, preoperative exposure to contrast was not associated with AKI within 7 days (odds ratio (OR) 0·95, 95 per cent c.i. 0·73 to 1·21; P = 0·669). The sensitivity analysis showed no association between preoperative contrast administration and AKI within 48 h after operation (OR 1·09, 0·84 to 1·41; P = 0·498).

CONCLUSION

There was no association between preoperative intravenous contrast administered for CT up to 7 days before surgery and postoperative AKI. Risk of contrast-induced nephropathy should not be used as a reason to avoid contrast-enhanced CT.

Development of Self-Healing Cement Slurry through the Incorporation of Dual-Encapsulated Polyacrylamide for the Prevention of Water Ingress in Oil Well

In the present work, a novel cross-linked polymer was synthesized though the anionic polymerization of cyanoacrylate with moisture as an initiator, methylene-bis-acrylamide as a cross-linker, and linseed oil as a spacer. Two layers of the synthesized polymer was coated over polyacrylamide for its homogenous impregnation in Class-G cement slurry for the synthesis of cement core. Fourier Transformation Infrared spectroscopy and X-Ray diffraction spectrum of the synthesized polymer and cement core were obtained to investigate the presence of different functional groups and phases. Moreover, the morphologies of the dual-encapsulated polyacrylamide was observed through scanning electron microscopy. Furthermore, the water-absorption capacity of the synthesized dual-encapsulated polyacrylamide in normal and saline conditions were tested. A cement core impregnated with 16% of dosage of dual-encapsulated polyacrylamide possesses an effective self-healing capability during the water-flow test. Moreover, the maximum linear expansion of the cement core was observed to be 26%. Thus, the impregnation of dual-encapsulated polyacrylamide in cement slurry can exhibit a superior self-healing behavior upon water absorption in an oil well.

Paraneoplastic Dermatomyositis with Cutaneous and Myopathic Disease Responsive to Adrenocorticotropic Hormone Therapy

Dermatomyositis is a myopathic or amyopathic autoimmune connective tissue disease that presents with classic dermatologic findings ranging from: poikilodermatous photosensitivity (shawl sign), eyelid edema and violaceous-pigmentation (heliotrope sign), lichenoid eruptions on the knuckles and elbows (Gottron's sign), periungual telangiectasias, and ragged cuticles (Samitz sign). Up to 30 percent of adult-onset cases of dermatomyositis may represent a paraneoplastic syndrome warranting a thorough work-up for malignancy. The authors present a case report of paraneoplastic dermatomyositis associated with triple negative, BRCA-1 positive, invasive intraductal carcinoma of the breast, whose myopathic and cuteanous symptoms were recalcitrant to high-dose corticosteroid therapy. Herein, the authors describe the first reported case of the use of an injectable adrenocorticotropic hormone agonist gel in a patient with myopathic paraneoplastic disease that achieved clinical resolution of both myopathic and cutaneous symptoms, but subseuqently developed significant hyperpigmentation of her face suspected to be secondary to a chemotherapeutic-induced pigmentary change which was augmented by adrenocorticotropic hormone therapy.

What's eating you? ant-induced alopecia (pheidole)

Ant-induced alopecia is a rare cause of acute, localized, nonscarring hair loss. It is most commonly caused by Pheidole pallidula ants, which can be found worldwide but are most common in Iran. The resulting alopecia can have many morphologic patterns (eg, patch, linear, nondiscrete) and thus ant-induced alopecia should be considered in the differential diagnosis for patients from endemic areas who present with new-onset localized hair loss. The condition is self-limited; however, patients should be evaluated for other more common causes of alopecia, especially in the absence of a convincing history.

Inflammatory Breast Carcinoma Presenting with Two Different Patterns of Cutaneous Metastases: Carcinoma Telangiectaticum and Carcinoma Erysipeloides

Cutaneous metastases can have many different clinical presentations. They are seen in patients with advanced malignant disease; however, they can be the initial manifestation of undetected malignancies. Inflammatory breast carcinoma is a rare and aggressive form of breast cancer that has a nonspecific appearance mimicking many benign conditions including mastitis, breast abscesses, and/or dermatitis. The authors report the case of a 40-year-old woman with inflammatory breast carcinoma presenting with violaceous papulovesicular lesions resembling lymphangioma circumscriptum and erythematous patches resembling erysipelas. These lesions represent two different types of cutaneous metastases, both of which were the initial signs of inflammatory breast carcinoma in the patient described herein. Skin biopsy of lesions confirmed invasive breast cancer and further prompted a work up for inflammatory breast carcinoma. This case demonstrates the importance of follow-up for all breast lesions, even those considered to be of benign nature, for they can be presenting signs of metastatic breast cancer.

Tumor with the features of both squamous cell carcinoma and melanoma (melanocarcinoma)

Combined tumors of malignant melanoma (MM) and squamous cell carcinoma (SCC) are extremely rare and have unknown biological potential. Different theories of their development, including collision and dual/divergent differentiation, are proposed. Although some observations suggest an indolent course for such tumors, a case of MM metastasis was reported in a patient who initially presented with a combined MM-SCC tumor. Re-excisions of such tumors may show MM in situ and should be treated accordingly. Herein we present another case of a combined MM-SCC tumor in a 78 male patient with lentigo maligna seen after complete re-excision of the tumor.

Parathyroid carcinoma: a silent presentation

Primary hyperparathyroidism is most commonly diagnosed in the setting of benign parathyroid adenoma(s). However, it can also rarely be caused by parathyroid malignancy and when it is, the clinical manifestations far supercede the presentation of benign parathyroid adenoma. We report a case of suspected benign parathyroid adenoma induced primary hyperparathyroidism in which pathologic diagnosis of parathyroid carcinoma was made. Due to the lack of signs and symptoms, this indicates parathyroid malignancy can be masked clinically as benign adenomas, until a histologic diagnosis can be ascertained.

Myiasis: A Traveler's Dilemma

Myiasis is a tropical infection most often caused by Dermatotobia hominis, also known as the botfly. It is rarely seen in the United States. The infection has a slow evolution and often presents with painful lesions that mimic furunculosis, boils, and infected cysts. The mechanism of infection is based on the deposition of botfly eggs onto an arthropod, which acts as a vector of transmission. The arthropod infects various hosts and botfly eggs are concomitantly deposited on the host. The Dermatobia eggs transform into their larval form and penetrate the skin through adjacent adnexal structures or through the arthropod-based site of inoculation itself. Growth of the organisms within the tissues causes painful cystlike lesions. This article describes cutaneous furuncular myiasis and discusses patterns of recognition and treatment modalities, with a case presentation of an individual diagnosed with the condition attained from a visit to Belize.

Importance of regulatory T cells in the pathogenesis of psoriasis: review of the literature

Psoriasis is a common chronic relapsing inflammatory cutaneous disease; the main role in the inflammation of this condition is played by lymphocyte Th1, Th17 and their cytokines. The activity of these cells is modulated by a particular kind of T cells recently described: the T regulatory cells (Treg). These are able to inhibit the immunological response and to maintain the cutaneous immunological homeostasis, thus preventing autoimmunity against self antigens. Few data are available in the literature as to Treg in psoriasis; several studies demonstrate that the function of these cells is impaired in this condition and treatments for psoriasis may increase the number and activity of Treg. The role of these cells in the pathogenesis of psoriasis is very important to understand how they may contribute to the development of this cutaneous disorder. In the near future it would be possible to target therapies at these defects, improving the activity of these cells and maintaining cutaneous homeostasis, preventing psoriasis or other inflammatory cutaneous conditions.

Clinical and descriptive genetic study of polydactyly: a Pakistani experience of 313 cases

Polydactyly, a common hereditary condition with additional digits in hands and/or feet, is a very attractive model to appreciate clinical and genetic heterogeneity. In order to get an insight into its phenotypic manifestations, we ascertained a cohort of 313 independent families with polydactyly from Pakistan; 35% cases turned out to be familial while 65% were sporadic. In majority of the index cases, polydactyly was presented as an isolated digit defect. Preaxial polydactyly types were 48.24% and postaxial were 51.8%. Familial polydactylies mainly had bilateral and symmetrical presentations, whereas sporadic cases were mostly unilateral and less often symmetrical. In the 313 index subjects a total of 508 limbs with additional digits were recorded. Variable expression was evident as the involvement of upper limbs was more common than the lower, right hand than the left, and left foot than the right. The present cohort establishes interesting epidemiological attributes of polydactyly in the Pakistani population and highlights its extraordinary clinical heterogeneity. Molecular analyses of this cohort are anticipated to elucidate novel genetic factors involved in the origin of additional digits in the growing limb and may provide clues to the role of stochastic factors in the etiology of phenotypic variability in polydactyly.

Study of effect of thermal annealing on crystalline perfection of bismuth germanate single crystals grown by low thermal gradient Czochralski method

Bismuth germanate single crystals containing low angle and very low angle boundaries were selected as specimen for annealing experiments at 1000 °C for varying lengths of time in the range: 8 h to 80 h. Specimen with larger surface along (111) and (100) planes were investigated. The tilt angles of the boundaries were found to be in the range: 16 arc sec to 88 arc sec. Half widths of the diffraction curves of different subgrains were in the range: 15 arc sec to 39 arc sec. High resolution X-ray diffractometry and topography were employed for structural characterization and secondary ion mass spectrometry (SIMS) was used for study of impurity distribution. Annealing led to significant improvement in the crystalline perfection of specimen and all but one of the boundaries could be removed. The very low angle boundaries, which could not be annealed out, had a tilt angle of 41 arc sec. The half widths of diffraction curves of the two remaining subgrains were: 10 arc sec and 17 arc sec. The growth of subgrains as a result of annealing was investigated. SIMS investigation of annealed specimen, in which a very low angle boundary persisted, showed the boundary was decorated with silicon impurity, which presumably acted as a pining center. Detailed diffractometric and topographic experiments helped in delineating the two subgrains around the very low angle boundary. The morphological features of the very low angle boundary were studied in detail.

Effect of variable pressure on growth and photoluminescence of ZnO nanostructures

Thin films constituted of equiaxed and one dimensional nanostructures of ZnO via metal-catalyst-free vapor phase were grown using a simplistic thermal evaporation technique under two different pressure conditions approximately of the order of 10(-1) and 10(-3) torr, respectively. ZnO deposited at low vacuum (approximately 10(-1) torr) exhibited the formation of nanograins of variable size between 60 to 180 nm. In contrast the film grown at high vacuum (approximately 10(-3) torr) resulted the nanowired type morphology with a random networking, generally distributed with equiaxed grains of film microstructure. The diameter of maximum number of these nanowires lies between 45 to 65 nm. The films grown at low vacuum has shown almost equal composition of Zn and O while the film grown at high vacuum has shown lower content of O. The nanowires formed under limited O (high vacuum: approximately 10(-3) torr) signifies the role of O vacancies during growth. It has been postulated that presumably under high vacuum deposition, initially formed ZnO transforms to ZnOx (x < 1) through creation of O vacancies due to limited presence of O. Subsequently ZnOx acts as self-catalyst and heterogeneous nuclei are responsible for the formation of nanowired type morphology. The effect of different microstructures has been correlated and discussed to understand the photoluminescence characteristics obtained on these films.

Effect of solar UV radiation on earthworm (Metaphire posthuma)

Human health risks like damage to the eyes, immune system, and skin are known to be associated with increasing ultraviolet radiation (UVR) in the environment. In this study, we evaluated the phototoxic effects of UVR in sunlight and its possible mechanism of action by using earthworm as an alternative model because earthworm skin contains several biomolecules (tetraene and triene sterol) similar to human beings. We studied the generation of reactive oxygen species (ROS), photooxidation of lipids, and histopathological changes in earthworm integument. It was observed that UVR-exposed earthworm skin homogenate produced a significant amount of singlet oxygen ((1)O(2)), superoxide anion (O(2)(*)(-)), hydroxyl radicals ((*)OH), and photooxidation of lipids. The production of ROS and lipid peroxidation product was found dependent on the dose of solar UVR in earthworm integument. Histological anomalies such as thickening, vacuolation, and hypertrophy of epidermal cells were observed when the animals were exposed for 1 to 2h, while a higher exposure period (3h) caused degeneration of circular and longitudinal muscles. Continuous sunlight exposure for more than 3h was found lethal to worms. These observations suggested that the current level of UVR in sunlight may produce significant phototoxic effects in the earthworms probably via the generation of ROS (photodynamic action). Possible increases in UVR in view of ozone depletion may be more detrimental to the biomolecules in the worm's skin. The earthworm thus turned out as a simple, sensitive, and cost-effective test organism for the assessment of the hazardous potential of solar radiation and also for planning safety measures for human beings.

Biochemical and genetic evidence for a family of heterotrimeric G-proteins in Trichomonas vaginalis

We have cloned a single copy gene from the human parasite Trichomonas vaginalis that encodes a putative protein of 402 amino acids with approximately 35% sequence identity to known alpha subunits of heterotrimeric G-proteins. It contains the characteristic GTP binding domains G-1 to G-5 with the key residues conserved. The new sequence has an unusual N-terminal extension of approximately 70 residues that cannot be aligned to reference G-proteins and which is characterised by proline-rich repeats. To investigate the expression and cellular localisation of the protein we produced specific antisera against a recombinant fusion protein. The antisera recognised a protein of an apparent molecular mass of 51 kDa in protein extracts from T. vaginalis and immunofluorescent microscopy established that the protein is localised to discrete endomembranes. Using a protocol designed to purify mammalian heterotrimeric G-proteins incorporating a GTPgammaS binding assay, we isolated two proteins from Trichomonas that are recognised by an heterologous GA/1 antisera raised to a peptide of the conserved G-1 domain of G-protein alpha subunits. These two proteins have an apparent molecular mass of 61 and 48 kDa, respectively, larger and smaller than the translation product of the cloned gene. Consistent with these results, the GA/1 antisera did not cross-react with the fusion protein produced from the gene we have cloned. These data suggest T. vaginalis possesses more than one heterotrimeric G-protein alpha subunit. Based on the sequence features of the cloned gene and the biochemical properties of the purified proteins, we suggest that these alpha subunits are likely to be part of classic heterotrimeric G-protein complexes.