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.

Unusual clinical and histopathological presentation of facial tuberculosis

Atypical facial lupus vulgaris is described in two cases. The first case resembled sarcoidosis clinically and histologically but responded well to ATT. The second case whose clinical diagnosis of lupus vulgaris was confirmed therapeutically had an atypical histology.

Isolation and Identification of novel toxins from a new mosquitocidal isolate from Malaysia, Bacillus thuringiensis subsp. jegathesan

A new mosquitocidal Bacillus thuringiensis subsp., jegathesan, has recently been isolated from Malaysia. Parasporal crystal inclusions were purified from this strain and bioassayed against fourth-instar larvae of Culex quinquefasciatus, Aedes aegypti, Aedes togoi, Aedes albopictus, Anopheles maculatus, and Mansonia uniformis. The 50% lethal concentration of crystal inclusions for each species was 0.34, 8.08, 0.34, 17.59, 3.91, and 120 ng/ml, respectively. These values show that parasporal inclusions from this new subspecies have mosquitocidal toxicity comparable to that of inclusions isolated from B. thuringiensis subsp. israelensis. Solubilized and chymotrypsin-activated parasporal inclusions possessed low-level hemolytic activity. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed that the crystals were composed of polypeptides of 77, 74, 72, 68, 55, 38, 35, 27, and 23 kDa. Analysis by Western blotting (immunoblotting) with polyclonal antisera raised against toxins purified from B. thuringiensis subsp. israelensis reveals that proteins in parasporal inclusions of subsp. jegathesan are distinct, because little cross-reactivity was shown. Analysis of the plasmid content of B. thuringiensis subsp. jegathesan indicates that the genes for toxin production may be located on 105- to 120-kb plasmids. Cry- clones that have been cured of these plasmids are nontoxic. Southern blot analysis of plasmid and chromosomal DNA from subsp. jegathesan showed little or low homology to the genes coding for CryIVA, CryIVB, and CryIVD from B. thuringiensis subsp. israelensis.

Characterization of human lymphoid cell lines GM9947 and GM9948 as intra- and interlaboratory reference standards for DNA typing

The incorporation of reference DNA is crucial to the validation of any DNA typing protocol. Currently, reference DNA standards are restricted to molecular size DNA ladders and/or tumor cell line DNA. Either of these, however, presents some limitations. We have rigorously characterized two Epstein-Barr virus (EBV)-immortalized human lymphoid cell lines--GM9947 (female) and GM9948 (male)--to determine their suitability as alternative in-line standards for three widely employed allele profiling strategies. Twenty-one highly polymorphic VNTR-based allelic systems (7 RFLPs, 2 AmpFLPs, and 12 STRs) distributed over 12 chromosomes were scrutinized along with 3 gender-based discriminatory systems. The genetic stability of each locus was confirmed over a period of 225 in vitro population doublings. Allele size estimates and degree of informativeness for each of the 21 VNTR systems were compiled. The reproducibility of allele scoring by traditional RFLP analyses, using both cell lines as reference standards, was also verified by an interlaboratory validation study involving 13 analysts from two geographically distinct forensic laboratories. Taken together, our data indicate that GM9947 and GM9948 genomic DNAs could be adopted as reliable reference standards for DNA typing.

Comparison of toxin overlay and solid-phase binding assays to identify diverse CryIA(c) toxin-binding proteins in Heliothis virescens midgut

The binding proteins, or receptors, for insecticidal Bacillus thuringiensis subsp. kurstaki delta-endotoxins are located in the brush border membranes of susceptible insect midguts. The interaction of one of these toxins, CryIA(c), with proteins isolated from Heliothis virescens larval midguts was investigated. To facilitate the identification of solubilized putative toxin-binding proteins, a solid-phase binding assay was developed and compared with toxin overlay assays. The overlay assays demonstrated that a number of proteins of 170, 140, 120, 90, 75, 60, and 50 kDa bound the radiolabeled CryIA(c) toxin. Anion-exchange fractionation allowed the separation of these proteins into three toxin binding fractions, or pools. Toxin overlay assays demonstrated that although the three pools had distinct protein profiles, similar-size proteins could be detected in these three pools. However, determination of toxin affinity by using the solid-phase binding assay showed that only one of the three pools contained high-affinity binding proteins. The Kd obtained, 0.65 nM, is similar to that of the unsolubilized brush border membrane vesicles. Thus, the solid-phase binding assay in combination with the toxin overlay assay facilitates the identification and purification of high-affinity B. thuringiensis toxin-binding proteins from the insect midgut.

Cloning, functional expression, and pharmacology of a GABA transporter from Manduca sexta

Termination of synaptic transmission occurs by several mechanisms that include uptake of the neurotransmitter molecules into the presynaptic neuron by specialized membrane transport proteins. We have cloned a (DABA)-sensitive gamma-aminobutyric acid (GABA) transporter from a cDNA library from Manduca sexta embryo. The cDNA clone, MasGAT, shows high sequence homology to known mammalian GABA transporters. The transcript is about 5.5 kb with an open reading frame of 1793 bp. Injection of a 2.2-kb cRNA from this clone into Xenopus oocytes results in [3H]GABA transport. A Michaelis-Menten kinetic analysis shows that GABA transport occurs by a high-affinity and saturable process, suggesting that it is carrier-mediated. Ion substitution studies also show the transport process to be highly dependent on extracellular Na+ gradient, a finding that is consistent with properties of known mammalian neurotransmitter transporters. Although MasGAT shares certain pharmacological similarities with known mammalian GABA transporters, this transporter is pharmacologically distinct from the known mammalian GABA transporters.

Mechanism of action of Bacillus thuringiensis toxins

The selectivity of Bacillus thuringiensis toxins is determined both by the toxin structure and by factors inherent to the insect. These toxins contain distinct domains that appear to be functionally important in toxin binding to protein receptors in the midgut of susceptible insects, and the subsequent formation of a pore in the insect midgut epithelium. In this article features necessary for the insecticidal activity of these toxins are discussed. These include toxin structure, toxin processing in the insect midgut, the identification of toxin receptors in susceptible insects, and toxin pore formation in midgut cells. In addition a number of B. thuringiensis toxins act synergistically to exert their full insecticidal activity. This synergistic action is critical not only for expressing the insecticidal activity of these toxins, but could also play a role in delaying the onset of insect resistance.

The impact of interactive image guided surgery: the Bristol experience with the ISG/Elekta viewing Wand

From June 1992 to August 1994 we have accumulated a 305 case experience with the ISG Viewing Wand, the first commercially available system for interactive image guided neurosurgery. Prior to the arrival of the wand 2.5% of intracranial procedures were carried out using the Leksell G frame for image guidance. Since the arrival of the wand that percentage of procedures suitable for image guidance has increased to 10%. The wand was used for 287 supratentorial procedures, 108 craniotomies, 48 trephine exposures, 34 burr hole biopsies, 4 ventriculoscopies and 1 shunt insertion, 19 posterior fossa explorations were performed, 28 skull base procedures, including 22 transsphenoidal pituitary operations, 3 petrousectomies and 3 orbital explorations were also carried out. In addition 3 spinal cases were included in the series, 2 transoral explorations and 1 sacral laminectomy. The technique was applicable to 193 tumour cases, 14 vascular cases including 7 aneurysms and 16 epilepsy cases. Both CT (70%) and MRI (30%) scans were used for image guidance. Contour matching algorithms were used for registration throughout. Since the arrival of the wand conventional stereotaxy has been used for 26 cases, 22 stereotactic biopsies, 2 thalamotomies and 2 craniotomies (0.5% of intracranial procedures). We conclude that contour matching, interactive image guidance using a mechanical arm has replaced frame based stereotaxy in our department except for point source localisation in deep midline structures. It is a technique that has universal application to intracranial neurosurgical procedures and as such represents a major advance in image guided neurosurgery.

THE PINEAL PARENCHYMAL NEOPLASMS - A CLINICOPATHOLOGICAL STUDY OF FOUR TUMOURS

Tumours of pineocytes are rare intracranial tumours. They are suspected once the effects of compression of neighbouring structures manifest. Four pineocytic neoplasms are reported, of which one was a spinal metastasis. Clinical features and radiological appearances are described. Histopathological diagnosis was based upon cytoarchitectural patterns which are discussed. Surprisingly all four cases occurred in a period of one month.