Identification of a Manduca sexta NSF ortholog, a member of the AAA family of ATPases

Transport between intracellular compartments requires the activity of an N-ethylmaleimide-sensitive fusion protein (NSF). NSF is a member of a growing family of ATPases regulating several membrane fusion reactions. We have cloned the NSF ortholog from the moth, Manduca sexta (MsNSF). MsNSF is highly conserved in domains critical for NSF function in vertebrates. MsNSF codes for a protein of 745 amino acids, translating to a M(r) of 83kDa in vitro. MsNSF is 72% and 61% similar in amino acid sequence to Drosophila and vertebrate NSFs, respectively. We expressed the D1 ATP domain of MsNSF toward which antibodies selective to MsNSF were generated. Affinity purified alpha-MsNSF antibodies detect a 83kDa protein which is highly enriched in nervous tissues. Levels of MsNSF expression are substantially lower in other tissues examined. Anti-MsNSF antibodies are capable of inhibiting vertebrate intra-Golgi transport of a cargo protein in vitro. The identification of NSF ortholog from Manduca, whose neuroendocrine system is well studied, should facilitate isolation of complexes involved in protein trafficking from insect models. Phylogenetic analysis of NSF and related proteins suggests that the members of the AAA family arose from different ancestors, since the ingroup was not monophyletic. Proteasomal subunits and p97 homologs form two distinct subfamilies, while NSF homologs branch in to the third.

Partial purification and characterization of Bacillus thuringiensis Cry1A toxin receptor A from Heliothis virescens and cloning of the corresponding cDNA

Although extensively studied, the mechanism of action of insecticidal Bacillus thuringiensis Cry toxins remains elusive and requires further elucidation. Toxin receptors in the brush border membrane demand particular attention as they presumably initiate the cascade of events leading to insect mortality after toxin activation. The 170-kDa Cry1Ac toxin-binding aminopeptidase from the tobacco budworm (Heliothis virescens) was partially purified, and its corresponding cDNA was cloned. The cDNA encodes a protein with a putative glycosyl phosphatidylinositol anchor and a polythreonine stretch clustered near the C terminus with predicted O-glycosylation. Partial purification of the 170-kDa aminopeptidase also resulted in isolation of a 130-kDa protein that was immunologically identical to the 170-kDa protein, and the two proteins had identical N termini. These proteins were glycosylated, as suggested by soybean agglutinin lectin blot results. Cry1Ac toxin affinity data for the two proteins indicated that the 130-kDa protein had a higher affinity than the 170-kDa protein. The data suggest that posttranslational modifications can have a significant effect on Cry1A toxin interactions with specific insect midgut proteins.

Steroid induction of a peptide hormone gene leads to orchestration of a defined behavioral sequence

At the end of each molt, insects shed the old cuticle by performing preecdysis and ecdysis behaviors. Regulation of these centrally patterned movements involves peptide signaling between endocrine Inka cells and the CNS. In Inka cells, we have identified the cDNA and gene encoding preecdysis-triggering hormone (PETH) and ecdysis-triggering hormone (ETH), which activate these behaviors. Prior to behavioral onset, rising ecdysteroid levels induce expression of the ecdysone receptor (EcR) and ETH gene in Inka cells and evoke CNS sensitivity to PETH and ETH. Subsequent ecdysteroid decline is required for peptide release, which initiates three motor patterns in specific order: PETH triggers preecdysis I, while ETH activates preecdysis II and ecdysis. The Inka cell provides a model for linking steroid regulation of peptide hormone expression and release with activation of a defined behavioral sequence.

Fasciotomy for exertional anterior compartment syndrome: is lateral compartment release necessary?

The standard surgery for exertional anterior compartment syndrome is fasciotomy of the anterior and lateral compartments of the leg. We prospectively studied the necessity of lateral compartment release, which can add morbidity and extend recovery. We performed 30 anterior compartment releases in 20 patients (10 bilateral operations) with exertional anterior compartment syndrome but not lateral compartment involvement. We alternately performed only an anterior compartment release or both anterior and lateral compartment releases on 10 patients. The 10 patients who underwent bilateral surgery each had, during the same surgery, an anterior and lateral compartment release on one leg and only an anterior compartment release on the other. All were athletes involved in running sports. Overall, satisfactory outcomes were seen in 90% of the limbs--93% (14 of 15) that had anterior compartment release and 87% (13 of 15) that had release of both compartments (no statistically significant difference). For the patients who had unilateral surgery, the average time for full return to sports was 8.1 weeks after anterior release only and 11.4 weeks after release of both compartments, a statistically significant difference. The average time for full return to sports after bilateral surgery was 12.1 weeks. Among these patients, seven said that the leg with only anterior release seemed to recover faster. We concluded that when doing a fasciotomy for exertional anterior compartment syndrome alone, a lateral compartment release is not necessary.

Immunochemical localization of the metabotropic glutamate receptors in the rat heart

The localization of the glutamate receptor outside of the central nervous system is becoming more evident. These receptors have been implicated in brain function and pathology. It can also be envisioned that they play a vital role in the physiology of other organs and systems. We recently reported the presence of ionotropic glutamate receptors in the rat heart. These were distributed differentially in specific cardiac structures, including nerve terminals, ganglion cells, and the conducting system. In this study, we investigated the presence and localization of the metabotropic glutamate receptors (mGluRs) in the rat heart by immunohistochemistry. The experimental data show that the mGluR 1alpha, mGLuR 2/3, and mGluR 5 are present in the rat heart. Their preferential localization includes nerve terminals, ganglion cells, and elements of the conducting system. The mGluR 5 was the only receptor located in the intercalated disks of the cardiac muscle and in the endothelial lining of the blood vessels. This preferential localization to the different components of the conducting system and cardiac neural structures suggest that they play a role in the physiology of the heart.

Odontoid process and C1-C2 corrective osteotomy through a posterior approach: technical case report

OBJECTIVE AND IMPORTANCE

To demonstrate a new posterior approach to the anterior elements of the atlas and the axis including the odontoid process.

CLINICAL PRESENTATION

A 36-year-old woman presented with ankylosing spondylitis and severe flexion deformity of the cervical spine. She had sustained a trauma 5 years previously, causing the inability to look forward or to open the jaw adequately. An examination demonstrated fixed flexion and rotation of the cervical spine, with no neurological deficit. Radiologically, there was fusion of C1, C2, and the clivus.

TECHNIQUE

The upper cervical vertebrae were exposed via a midline posterior incision, the posterior arch of C1 was excised, and the vertebral arteries were mobilized. A wedge osteotomy was performed through the lateral masses of C1 and subsequently through the odontoid. The head was repositioned, and C1-C2 lateral mass screws and a Ransford loop were inserted.

CONCLUSION

It is possible to gain sufficient surgical access to the odontoid process via a posterior approach. The technique described is of benefit when the alternative anterior approaches to the upper cervical spine are technically difficult or impossible.

Gastrointestinal mucormycosis--an uncommon isolated mucormycosis

BACKGROUND

Isolated mucormycosis of the gastrointestinal tract is uncommon, with only two case reports from India.

OBJECTIVES

To study the clinicopathologic features of gastrointestinal mucormycosis in Indian patients.

METHODS

Eight cases of isolated gastrointestinal mucormycosis, seen over six years (1992-97) are reviewed.

RESULTS

Five of the patients were premature babies or infants, one was a 12-year-old boy, and two were middle aged. Symptomatology included vomiting, bloody diarrhea, upper gastrointestinal bleeding, abdominal lump and abdominal distention. All the neonates presented with intestinal perforation. The duration of symptoms was ten days or less in six cases. Mucormycosis was not suspected clinically in any patient. In six cases the diagnosis was established antemortem from resection or biopsy material. Only two patients received antifungal therapy and only one patient responded.

CONCLUSIONS

Isolated gastrointestinal mucormycosis is not uncommon in India. Early diagnosis may be helpful in reducing the high mortality.

Arteriovenous malformation of knee masquerading as juvenile arthritis

This is a rare case of involvement of knee joint by an arteriovenous malformation. A nine year old girl had recurrent monoarticular pain and swelling of long duration and had been treated as juvenile rheumatoid arthritis. Angiographic and histological features suggested an arteriovenous malformation of lower thigh with knee joint involvement.

Adrenal lipoma. A case report

Lipoma of the adrenal gland is an extremely uncommon tumor detected incidentally at postmortem or during life when the patient undergoes investigations for other reasons. All tumors reported in the literature were very small in size. We report a case of lipoma of the adrenal gland in a 45-year-old male patient who was hypertensive and presented with pain in the abdomen. The symptomatic presentation, large size, laparoscopic removal and rarity of this tumor merit documentation in the literature.

Cloning of the V-ATPase B subunit cDNA from Culex quinquefasciatus and expression of the B and C subunits in mosquitoes

The V-ATPase B subunit cDNA isolated from the midgut and Malpighian tubules of Culex quinquefasciatus larvae has a 1476 bp ORF encoding a 492 amino acids protein with a predicted mass of 54.8 kDa. Northern blot analysis reveals the presence of 1.8 and 4.2 kb transcripts in larvae and a 3.0 kb transcript in pupae. A single 57 kDa protein band is detected in immunoblot analysis of protein extracts from C. quinquefasciatus and A. aegypti larvae. Using antibodies to the B subunits we demonstrate high-level expression of these subunits in ion-transporting cells of caeca and anterior midgut, and in Malpighian tubules and rectum. High V-ATPase expression was also observed in the larval salivary glands, central nervous system neurophile, the thoracic endocrine complex and in imaginal discs.

Molecular and immunochemical characterization of the ionotropic glutamate receptors in the rat heart

Excitatory amino acids (EAA) and glutamate receptors (GluRs) play a fundamental role in the central nervous system (CNS). Ionotropic glutamate receptors (iGluRs) are coupled to ion channels, which are classified according to their most selective agonists. These ligand-gated channels are permeable to Na+, K+, and Ca+. Interaction of EAA receptor is linked to Ca+2/Na+ influx. Influx changes lead to an action potential, which in the heart is transmitted along the cardiocyte membrane. Furthermore, the heart has a rich innervation and specialized conduction system for rapid conduction and regulation of cardiac rhythmicity. Availability of EAA receptors in the heart might be important for cardiac function. The following GluRs were cloned by isoform-specific RT-PCR from rat heart ribonucleic acid (RNA): GluR 1, GluR 3, GluR 4, GIuR 7, Ka 1, and Ka 2. Expression in cardiac tissue was confirmed by western (for anti-GluR 2/3) and northern blots (for GluR 3, NMDAR 1, and Ka 2). The anatomical distribution was investigated by immunohistochemistry. Antibodies to GluR 2/3, GluR 5/6/7, Ka 2, and NMDAR 1 showed the strongest signals. These signals were specifically localized to cardiac nerve terminals, ganglia, conducting fibers, and some to myocardiocytes particularly in the atrium. Each antibody had a specific pattern of distribution. This anatomical localization suggests that they might play a role in cardiac electrophysiology and pathology.

Surgical experience with an implanted artificial cervical joint

OBJECT

To assess the effectiveness of Cummins' artificial cervical joint, the authors reviewed the cases of 20 patients in whom the joint had been placed.

METHODS

A review of patients' medical records and reexamination of 18 patients were performed. The review of the surgical experience with the implantation of movable stainless-steel joints in 20 patients treated for cervical myelopathy (16 patients), cervical radiculopathy (three patients), and severe pain (one patient) indicated that the procedure is safe and well tolerated and does preserve cervical joint motion in most patients over an extended period of observation. To date, adjacent segmental symptomatic degenerative changes leading to further surgical treatment have been avoided. The joint has been placed in patients with advanced congenital and acquired cervical fusion and has been demonstrated to be stable, mobile, and biomechanically and biochemically compatible; it has shown no subsidence into adjacent bone. Wear debris has not occurred.

CONCLUSIONS

The use of stainless steel in the cervical spine appears to be suitable for this joint replacement design.

Isolation of the V-ATPase A and c subunit cDNAs from mosquito midgut and Malpighian tubules

Using conserved amino acid sequences for the design of oligonucleotide primers, we isolated cDNA clones for two subunits of the V-ATPase from the midgut and Malpighian tubules of Aedes aegypti larvae. The 3.1 kb cDNA of the A subunit of the peripheral catalytic V1 sector codes for a protein of 68.6 kDa. The protein contains conserved motifs, including an ATP/GTP binding site, found in all other A subunits. Southern analysis using the A subunit as a probe suggests the presence of only a single copy of gene in the Aedes aegypti. The 0.85 kb cDNA of the c subunit of the membrane H+ conducting V0 sector codes for a protein of kDa. This protein has four transmembrane domains and contains a conserved glutamic acid that serves as the binding site for dicyclohexylcarbodiimide. Southern analysis using the c subunit as a probe suggests the presence of more than one related gene in the genome of Aedes aegypti. Pileup analysis of various A and c subunits shows that these subunits fall into distinct clusters, including one in which all arthropod proteins are clustered.

A glucose-regulated protein, GRP58, is down-regulated in C57B6 mouse liver after diethylhexyl phthalate exposure

Diethylhexyl phthalate (DEHP) is a widely used plasticizer that induces peroxisome proliferation in rodents. Prolonged exposure to DEHP results in a variety of toxic effects, the most significant of which appears to be an increased incidence of liver cancer and male reproductive toxicity in rodents. Accompanying these toxic effects is the induction of a number of genes within the liver, particularly those genes involved in peroxisomal fatty acid beta-oxidation and members of the cytochrome P450 family, CYP4A. In order to explore which additional genes may be altered by DEHP exposure, mRNA differential display was performed using total liver RNA from male C57B6 mice that were treated with either O or 2% DEHP in their diet for 7 days. In doing so, a number of partial cDNAs representing messages that are potentially differentially expressed have been isolated. One of these cDNAs was found to be similar to the previously cloned gene, GRP58. Analysis by RNase protection assay and North hybridization have shown that the transcript for GRP58 is down-regulated in the liver after DEHP exposure. Analysis of dose-response exposures to DEHP by reverse transcription (RT)-PCR confirm these results and also shows that GRP58 is not altered in kidney or testis. Immunoblot analysis using GRP58-specific antibodies also shows a decrease in GRP58 protein levels in DEHP-treated mice. Moreover, exposure of mice to another peroxisome proliferator, clofibrate, results in a slight down-regulation of GRP58 at the highest dose, 0.5%. Thus, it appears as if DEHP and clofibrate can use different pathways to affect gene expression.

Molecular cloning and characterization of a novel mosquitocidal protein gene from Bacillus thuringiensis subsp. fukuokaensis

A novel mosquitocidal protein gene, cry20Aa, was cloned from Bacillus thuringiensis subsp. fukuokaensis (H-3a: 3d: 3e). The gene product, Cry20Aa, was naturally truncated and had a molecular mass of 86,138 Da. The Cry20Aa protein possessed five conserved sequence blocks, as do most other insecticidal Cry toxins. However, an amino acid comparison of Cry20Aa with other mosquitocidal toxins, including Cry4A, Cry4B, Cry10A, Cry11A, and Cry11B, demonstrated that Cry20Aa was quite different from other toxins except for the conserved blocks. The N terminus of Cry20Aa was, however, homologous to the N termini of Cry4A and Cry10A. Interestingly, an inverted repeat (IR1) sequence in the open reading frame of the cry20Aa gene caused incomplete expression of Cry20Aa. When this internal IR1 sequence was altered with no change of amino acid sequence, acrystalliferous B. thuringiensis cells transformed with cry20Aa gene dramatically produced crystal inclusions. However, the intact 86-kDa Cry20Aa protein is highly labile, and it is rapidly degraded to polypeptides of 56 and 43 kDa. To increase expression of the cry20Aa gene, the p20 chaperonelike protein and the cyt1Aa promoter were utilized. While p20 did not increase Cry20Aa expression or stability, chimeric constructs in which the cry20Aa gene was under control of the cyt1Aa promoter overexpressed the Cry20Aa protein in acrystalliferous B. thuringiensis. The expressed Cry20Aa protein showed larvicidal activity against Aedes aegypti and Culex quinquefasciatus. However, the mosquitocidal activity was low, probably due to rapid proteolysis to inactive 56- and 43-kDa proteins.

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.