Functional characterization of RNase H1 from Drosophila melanogaster

We have cloned and functionally characterized the RNase H1 gene from D. melanogaster. The longest open reading frame consists of 5 exons that encode a 333 amino acid protein with a molecular mass of 37.1 kDa. This is the first demonstration of specific nuclease activity of a cloned RNase gene from a multicellular higher eukaryote. No additional proteins or cofactors are required for this nuclease activity. Comparison of Drosophila RNase H1 amino acid sequence to that of other cellular eukaryotic homologs reveals the presence of three evolutionarily distinct domains. The N- and C-terminal conserved domains are connected by a highly variable domain. The C-terminal domain has high amino acid similarity to bacterial RNase HI and the RNase H domain of retroviral reverse transcriptase, while the N-terminus, of unknown function, is similar to the P6 translational activator of caulimoviruses.

Quantitative differences in endolymphatic calcium and endocochlear potential between pigmented and albino guinea pigs

A number of previous studies have suggested that melanin may play a role in Ca2+ homeostasis of endolymph. In the present study, endolymph Ca2+ levels and endocochlear potential (EP) were measured in all four cochlear turns of pigmented or albino guinea pigs. Auditory sensitivity was also evaluated using cochlear action potential (AP) thresholds. In pigmented animals we found that endolymph Ca2+ tended to increase from base to apex of the cochlea, while EP systematically decreased towards the apex. In contrast, no significant Ca2+ gradient was found in albinos and the EP decline was far less. As a result, the apical turn of albino animals had significantly lower Ca2+ and significantly higher EP than in pigmented animals. AP thresholds pooled across all test frequencies were significantly lower in albino animals although no differences at individual frequencies reached significance. Even after correction for EP differences, the endolymph Ca2+ levels in albino animals were significantly lower than in pigmented ones. These results confirm that there are significant physiologic differences between pigmented and albino animals, which are a likely consequence of the absence of melanin in the albino cochlea. They are consistent with the involvement of melanin in the active transport of Ca2+ into endolymph.

Suppression of cytochrome P450 Cyp2f2 mRNA levels in mice by the peroxisome proliferator diethylhexylphthalate

Exposure to peroxisome proliferators, which are extensively used, causes a number of pleiotrophic effects. Prolonged exposure to the peroxisome proliferator, DEHP, causes hepatic hyperplasia and liver tumors in rats and mice. This exposure can also induce a number of enzymes. To identify additional genes that are regulated by DEHP, mRNA differential display was used. One of the genes affected is cytochrome 450 Cyp2f2, a naphthalene hydroxylase. Using northern analysis, RNase protection assay, and RT-PCR, we show that the Cyp2f2 mRNA levels are decreased in mouse liver following DEHP treatment. A smaller Cyp2f2 mRNA transcript was also detected in kidney and these transcript levels were also suppressed but to a lesser extent than that in the liver. The response to DEHP in mouse liver is both dose and time dependent.

Primary structure of an invertebrate dihydrolipoamide dehydrogenase with phylogenetic relationship to vertebrate and bacterial disulfide oxidoreductases

Dihydrolipoamide dehydrogenase (E3) is a flavoprotein component of multi-enzyme complexes catalyzing oxidative decarboxylation of alpha-ketoacids in the Krebs' cycle. We have cloned a 2.4-kb E3 cDNA from an arthropod, Manduca sexta, that codes for 497 amino acids and translates to a 51-kDa protein in vitro. Sequences at and around the dinucleotide binding domains, disulfide active site and the C-terminal interface domain involved in substrate binding are highly conserved in Manduca E3. Phylogenetic analysis of protein sequences from the flavoprotein class of disulfide oxidoreductases family of enzymes suggests that in spite of the homologous nature of E3 and glutathione reductase (goR) in sequence and structure, E3 shares a common ancestor with mercuric reductase (merA), whereas goR is more related to trypanothione reductase (tryR) than to other members. All members, except goRs, seemed to be monophyletic. Plant goRs seemed to have arisen differently and are more closely related to tryRs than to bacterial and vertebrate goRs. Earlier speculation on the nature of origin of E3 in Pseudomonas is not supported by phylogenetic data. A possible structural relationship of Manduca E3 to other pyridine-binding proteins, such as the neurotransmitter transporters and channels, is proposed.

Marginal cross-resistance to mosquitocidal Bacillus thuringiensis strains in Cry11A-resistant larvae: presence of Cry11A-like toxins in these strains

Culex quinquefasciatus mosquito larvae resistant to the Cry11A toxin showed marginal cross-resistance to the multiple toxin crystals from B. thuringiensis subsp. israelensis and also to toxin crystals from three other mosquitocidal strains, i.e. B. thuringiensis subsp. fukuokaensis, subsp. jegathesan, and subsp. kyushuensis. Cross-resistance patterns of the Cry11A-resistant larvae to mosquitocidal strains of B. thuringiensis together with the immunological screening using antisera raised against Cry11A indicated the presence of Cry11A-like toxins in these strains and could be used as a screening tool for the identification of novel toxins. The Cry11A-resistant larvae had significantly less resistance to the Cry11B toxin from B. thuringiensis subsp. jegathesan. The occurrence of cytolytic toxins in all of these mosquitocidal strains partially explains the marginal cross-resistance observed with multiple toxin crystals since each of these crystals also contains cytolytic toxins.

Cloning and characterization of a cytolytic and mosquitocidal delta-endotoxin from Bacillus thuringiensis subsp. jegathesan

A cytolytic toxin gene encoding a 30.1-kDa Cyt2Bb1 toxin protein from B. thuringiensis subsp. jegathasan was cloned employing a limited-growth PCR screening method with forward and reverse oligonucleotide primers designed from N-terminal amino acid sequences of native and trypsin-cleaved protein, respectively. The expressed protein showed little cross-reactivity to the antibody raised against the Cyt1Aa protein. Unlike Cyt1Aa and Cyt2Aa expression, there was little or no visible crystal inclusion formation under microscopic observation. The amino acid sequence alignment indicated 31 and 66% identity to Cyt1Aa and Cyt2Aa, respectively. The sequence alignment for five known cytolytic proteins indicated three highly conserved regions, two in the loop regions between alpha-helices and beta-sheets and one in the loop region between beta-sheets 5 and 6. beta-Blocks 4 to 7 are also conserved, not only structurally but also among the amino acids in the hydrophobic faces. Mosquitocidal activity assays indicated that the Cyt2Bb toxin had less toxicity than Cyt1Aa and had about 600-times-lower toxicity than the wild-type whole toxin crystal. However, both the Cyt2Bb and the Cyt1Aa toxin showed comparable levels of hemolytic activity.

Ductin, a component of the V-ATPase, is developmentally regulated in Heliothis virescens midgut, and anti-ductin antibodies label lateral membranes

We previously cloned from Heliothis virescens a 16-kDa protein that is homologous to other ductin sequences. We also reported its immunolocalization with a specific affinity-purified anti-peptide antibody in the midgut and Malpighian tubule of feeding larvae, and concluded that the cloned proteolipid encodes the V-ATPase proton-transporting subunit c from the V0 sector. We now present the immunolocalization of this protein in the midgut during the L4-L5 larval molt and early post-ecdysis into the fifth instar in H. virescens. The results show that the spatial expression of the 16-kDa protein is developmentally regulated. Labeling by anti-peptide antibody varies during the molt in the midgut goblet cell apical plasma membrane and the goblet cell apical valve. Epifluorescence and confocal microscopy revealed strong anti-ductin labeling in areas of cell-to-cell contact during the molt, and during early post-ecdysis into the fifth larval instar. The characteristic labeling pattern observed in areas of cell-to-cell contact is consistent with the claimed involvement of ductins in gap junctions. Conclusive evidence for the presence of the 16-kDa protein in areas of cell-to-cell contact in the midgut of feeding larvae is, however, lacking. V-ATPase regulation during the molt was also investigated by simultaneous immunohistochemistry with an anti-B subunit antiserum, a probe for the V1 sector.

A systematic review of the evidence for hypodermoclysis to treat dehydration in older people

BACKGROUND

The purpose of the study was to evaluate the evidence supporting the use of hypodermoclysis (i.e., subcutaneous infusion of fluids) to treat dehydrated elderly patients, and to discuss clinical applications of this mode of therapy in the long-term care setting.

METHOD

Articles reporting the use of hypodermoclysis were identified using a systematic MEDLINE search between January 1966 and May 1996. Articles were included in our sample if they contained original patient data that evaluated either the efficacy or adverse effects associated with the use of subcutaneous infusions to treat dehydration in adults, whether hyaluronidase was required to facilitate the absorption of subcutaneous fluid, or if potassium could be added to the solution.

RESULTS

Eighteen articles met the inclusion criteria. Since we hypothesized that adverse effects associated with hypodermoclysis may have been related largely to the use of nonelectrolyte or hypertonic solutions, the studies were evaluated according to the type of fluid administered. Six hundred and eighty-five patients were described in 13 studies evaluating the efficacy and toxicity of subcutaneously administered fluid. Four studies evaluated hypodermoclysis using electrolyte-containing solutions in 25 patients. Two of these were randomized control trials (RCT) that compared hypodermoclysis to intravenous therapy. Both reported similar absorption of fluids. In the single RCT that evaluated adverse effects, 4 of 17 patients receiving hypodermoclysis reported minor side effects similar to those reported with intravenous therapy. Adverse effects were more severe when electrolyte-free or hypertonic solutions were evaluated. Of the 639 patients who may have received electrolyte-free solutions, 16 patients (2.5%) reported adverse effects, 8 of which were severe. Both patients reported to have received hypertonic solutions noted adverse effects, one of which was severe. The use of hyaluronidase to facilitate absorption was evaluated in 74 patients. These studies suggest that hyaluronidase improves the speed of fluid absorption but may not change the patient's comfort level. A single case report of 350 subcutaneous infusions in 67 patients investigated the administration of up to 34 mmol/L of potassium chloride (KCl) by hypodermoclysis. The only adverse reaction observed was discomfort at the infusion site.

CONCLUSIONS

Hypodermoclysis can be used to most safely provide fluids when electrolyte-containing fluids are administered. Hypodermoclysis may have fallen into disuse because of reports of severe adverse reactions related to infusions of electrolyte-free or hypertonic solutions that would likely be considered inappropriate today. Whether or not hyaluronidase is required to promote subcutaneous fluid absorption remains unresolved. Limited evidence suggests that potassium chloride may, with caution, be safely added to subcutaneous infusions. The majority of the available studies evaluating hypodermoclysis are of poor quality. Because of the tremendous potential benefits of administering fluid subcutaneously, there is a need for good quality studies to evaluate the efficacy of hypodermoclysis.

Second-look surgery for incompletely resected fourth ventricle ependymomas: technical case report

OBJECTIVE AND IMPORTANCE

The prognosis for patients with ependymomas is related to the adequacy of surgical clearance. It is, however, often not possible to obtain a macroscopically complete resection of tumors arising in the posterior fossa. This may be because of the involvement of structures, the sacrifice of which would result in unacceptable morbidity, or because of metastatic lesions at diagnosis. For those patients in whom initial surgery was incomplete, elective second-look surgery may allow more complete clearance of tumor.

INTERVENTION

We have performed second-look surgery for fourth ventricle ependymomas in five patients: two women, aged 26 and 27 years, and three male patients, aged 4 months, 19 months, and 18 years. The 19-month-old male patient underwent early second-look surgery without receiving any interim chemotherapy. Second-look surgery on the other four patients was performed after they had received chemotherapy. No additional major morbidity was associated with the subsequent surgery, which achieved macroscopically complete clearances in four of the five patients. Three of four patients who underwent macroscopically complete resections were well, without clinical or radiological evidence of recurrent tumor, at 23, 25, and 34 months after their second operations. The 10-month-old patient who underwent early second-look complete resection relapsed locally at 33 months after surgery. Complete resection was not possible in one patient who had progressive tumor 8 months after second-look surgery.

CONCLUSION

For patients in whom complete excision of fourth ventricle ependymomas is not possible at initial surgery, second-look procedures may enable macroscopic clearance to be achieved with little morbidity. A larger study is needed to evaluate this approach to treatment.

Histopathological study of hyperkeratosis of palms and soles

Clinically it is sometimes difficult to differentiate the various hyperkeratosis of palms and soles like psoriasis of palms and soles, pustulosis palmaris et plantaris, hyperkeratotic tinea and hyperkeratotic eczema. To differentiate amongst these conditions we have to take the help of histopathology. Here we are presenting the data of 292 cases of hyperkeratosis of palms & soles examined histologically by doing Haematoxylin and Eosin staining for the typical changes of the above mentioned conditions and PAS for the demonstration of the fungus in stratum corneum in cases of hyperkeratotic tinea.

Hyperkeratosis of palms and soles : clinical study

Typical lesions of hyperkeratosis of palms and soles do not create any problem but when slight variation is there it becomes difficult to diagnose and that changes the line of treatment. For that we have studied 300 fresh cases of hyperkeratosis of palms and soles which included 110 cases of hyperkeratotic eczema. 42 cases of hyperkeratotic tinea, 64 cases of psoriasis of palms and soles and 84 cases of pustulosis palmaris et plantaris (PPP). To reach the final diagnosis alongwith the detailed history, general physical examination and routine investigations, help was taken of special investigations like pus for culture and sensitivity, KOH smear examination of skin scrapings and nail cutting and culture on Sabouraud's dextrose agar medium.

Ensuring recovery of intact RNA from rat pancreas

The isolation of intact RNA from rat pancreas is compromised by autolysis and by the presence of endogenous ribonucleases. In order to ameliorate recovery we systematically investigated available RNA extraction methods and paid particular attention to the influence of frozen storage and ribonuclease inhibition strategies on overall yield and quality of RNA. Modifications to the basic procedure of Chomczynski and Sacchi (1987) are described which allow, reproducibly, to obtain rat pancreatic RNA suitable for Northern blot hybridization, RT-PCR, and differential display analysis.

Clinicopathological correlation in 50 cases of erythroderma

Fifty cases of erythroderma were studied clinically and histopathologically. Clinically 11 were of eczemas, 12 of psoriasis, 14 were drug-induced, 11 of idiopathic group and 1 each of pemphigus foliaceus (PF) and cogenital bullous ichthyosiform erythroderma (CBIE). Histopathologically 10 cases of psoriasis, 1 of PF and 1 of CBIE showed specific histopathology and therefore clinical histopathological correlation was possible only in 12 (24%) cases. Exact differentiation in erythroderma due to eczemas, drugs or idiopathic was not possible histopathologically.

Histopathological study of 60 cases of cutaneous vasculitis

Sixty cases of cutaneous vasculitis were selected from department of Skin and STD, Government Medical College/Rajendra Hospital, Patiala. Detailed history, general physical examination, systemic examination and dermatological examination were conducted in each and every case. Routine investigations were done. Clinical diagnosis was confirmed by biopsy. Histopathologic study was conducted by using H & E stain under 100X and 400X by light microscopy.

Psoriasiform sarcoidosis associated with depigmentation

A 65-year-old female had psoriasiform, depigmented, angiolupoid, lupus pernio, papular and verrucous plague type of cutaneous sarcoidosis. Systemic involvement (hepatomegaly, bilateral persistent swelling of the parotid glands, pain in the hands, weakness and atrophic rhinitis of the left nasal cavity) was also present. The histopathological features of a non-caseating epithelioid cell granuloma with giant cells confirmed the diagnosis. The patient is responding favourably to prednisolone 10 mg daily.

Atypical manifestations of tinea faciei

A study of 58 paitents of tinea faciei was conducted. Twenty five (43.1%) patients had history of photosensitivity. Twenty eight (48.2%) patients were applying topical steroids, 2 (3.4%) patients were on 10 mg of prednisolone daily. Associated tinea of other sites were observed in 14 (24.13%). 23 (39.6%) patients had typical circinate, arcuate, annular plaques with raised margin showing vesiculo-pustules. Atypical manifestations were in the form of arcuate plaques on the pinna in 4 patients, erythematous plaques full of vesiculo-pustules without central clearing in 3. Thirty two (55.17%) patients had plaques with broad edges and indistinct central clearing. In 2 patients lesions resembled discoid lupus erythematosus. Skin scrapings for fungus was positive in 36 (62.06%) cases. All patients responded to systemic griseofulvin 10mg/kg with 1% clotrimazole topicaly in 4-8 weeks.

Lichen planus and lupus erythematosus overlap syndrome

A 45-year-old woman with livid plaques showing central atrophy and erythematous vesicular borders over both dorsa of feet and buttocks, and follicular and papular lesions over buttocks and lumbar area, was difficult to diagnose as either lichen planus (LP) or lupus erythematosus (LE). The histological studies from two places showed features of both LE and LP. Laboratory findings were within normal limits first, but follow up studies for two years showed persistent albuminurea, leucopenia, arthritis and erythema over the exposed areas with same histology suggesting that eruption may be an unusual variant of LE.

Immunolocalization of the 17 kDa vacuolar H(+)-ATPase subunit c in Heliothis virescens midgut and malpighian tubules with an anti-peptide antibody

The transmembrane sector of V-ATPases is involved in proton conduction across the membrane where a 15-17 kDa proteolipid forms a putative proton channel. An affinity-purified rabbit polyclonal antibody was developed to an antigenic and putatively extracellular region of a cloned 17 kDa proteolipid. In larval tissue sections, this antibody labeled the midgut goblet cell apical membrane in Heliothis virescens (Lepidoptera: Noctuidae) and the apical membrane in Malpighian tubules from H. virescens and Manduca sexta (Lepidoptera: Sphingidae). The antibody also recognized the 17 kDa protein in an immunoblot of H. virescens Malpighian tubule homogenate. Northern blot analysis revealed the presence of two transcript sizes in the midgut (1.9 and 1.2 kb) and Malpighian tubules (2.2 and 1.9 kb). Our results strongly support the hypothesis that the 17 kDa protein is a component of the V-ATPase, where it is thought to be the proton-conducting subunit. This polyclonal antibody may provide a powerful tool for V-ATPase regulation studies, while the use of the anti-peptide antibody approach may be helpful for the immunolocalization of other ductins.

Identification, isolation, and cloning of a Bacillus thuringiensis CryIAc toxin-binding protein from the midgut of the lepidopteran insect Heliothis virescens

Bacillus thuringiensis toxins are insecticidal to a variety of insect species. The selectivity of the toxins produced by these bacteria is dependent on both the toxin structure and the receptor sites that are present in different insect species. One of these toxins, CryIAc, is highly insecticidal to the noctuid pest Heliothis virescens. Using toxin overlay assay, a 120-kDa glycoprotein was identified as a toxin-binding protein. This protein was partially purified, its N-terminal sequence was determined, and the full-length cDNA encoding this protein was isolated from a H. virescens midgut library. The B. thuringiensis toxin-binding protein, BTBP1, has high homology to aminopeptidase N from eukaryotes and prokaryotes.