Neuronal nitric oxide synthase and calmodulin-dependent protein kinase IIalpha undergo neurotoxin-induced proteolysis

Calpain (calcium-activated neutral protease) has been implicated as playing a role of neuronal injury in cerebral ischemia and excitotoxicity. Here we report that, in addition to extreme excitotoxic conditions [N-methyl-D-aspartate (NMDA), alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA), and kainate challenges], other neurotoxins such as maitotoxin, A23187, and okadaic acid also induce calpain activation, as detected by m-calpain autolytic fragmentation and nonerythroid alpha-spectrin breakdown. Under the same conditions, calmodulin-dependent protein kinase II-alpha (CaMPK-IIalpha) and neuronal nitric oxide synthase (nNOS) are both proteolytically cleaved by calpain. Such fragmentation can be reduced by calpain inhibitors (acetyl-Leu-Leu-Nle-CHO and PD151746). In vitro digestion of protein extract from cortical cultures with purified mu- and m-calpain produced fragmentation patterns for CaMPK-IIalpha and nNOS similar to those produced in situ. Also, several other calpain-sensitive calmodulin-binding proteins (plasma membrane calcium pump, microtubule-associated protein 2, and calcineurin A) and protein kinase C-alpha are also degraded in neurotoxin-treated cultures. Lastly, in a rat pup model of acute excitotoxicity, intrastriatal injection of NMDA resulted in breakdown of CaMPK-IIalpha and nNOS. The degradation of CaMPK-IIalpha, nNOS, and other endogenous calpain substrates may contribute to the neuronal injury associated with various neurotoxins.

Crystal structure of calcium bound domain VI of calpain at 1.9 A resolution and its role in enzyme assembly, regulation, and inhibitor binding

The three dimensional structure of calcium-bound domain VI of porcine calpain has been determined to 1.9 A resolution. The crystal structure reveals five EF-hands, one more than previously suggested. There are two EF-hand pairs, one pair (EF1-EF2) displays an 'open' conformation and the other (EF3-EF4) a 'closed' conformation. Unusually, a calcium atom is found at the C-terminal end of the calcium binding loop of EF4. With two additional residues in the calcium binding loop, the fifth EF-hand (EF5) is in a 'closed' conformation. EF5 pairs up with the corresponding fifth EF-hand of a non-crystallographically related molecule. Considering the EF5's role in a homodimer formation of domain VI, we suggest a model for the assembly of heterodimeric calpain. The crystal structure of a Ca2+ bound domain VI-inhibitor (PD150606) complex has been refined to 2.1 A resolution. A possible mode for calpain inhibition is discussed.

Multifocal gastric neoplasia after recurrent laser therapy for the watermelon stomach

Repeated laser therapy has become an accepted therapeutic approach in the treatment of watermelon stomach, and to date no important negative sequelae have been reported. The case of a patient who underwent repeated sessions of neodymium: yttrium aluminum garnet (Nd:YAG) laser therapy over a five-year period for the treatment of the watermelon stomach is presented. Postlaser therapy the patient developed deep ulcerations that would heal; however, he ultimately developed a nodular antrum. Random biopsies of antral nodules revealed carcinoma-in-situ. A Billroth I gastrectomy revealed two foci of carcinoma-in-situ/high grade dysplasia and multiple foci of lower grades of dysplasia. This case suggests a possible association between use of laser therapy and development of gastric neoplasia.

Differential expression of a cDNA clone in human liver versus hepatic cancer--highly homologous to aryl-dialkyl-phosphatase

We applied the technique of mRNA differential display to normal liver tissue and hepatoma cell line Hep3B. One of the isolated cDNA clones was expressed in human normal liver tissue but not in the human hepatocarcinoma cell line. Northern Blot analysis confirmed that high level of mRNA was expressed in human normal liver tissue but the level was decreased in non-cancerous liver tissue from hepatoma patients. Low level or no expression was observed in human hepatoma tissue. One of these transcripts was about 1.8 kb in length. Southern Blot analysis showed that it was a single copy gene. We obtained a full length cDNA clone of 2,395 bp by screening human liver 5'-stretch plus cDNA library. Nucleotide sequence indicated that this clone was highly homologous to aryl-dialkyl-phosphatase and possessed two polymorphic sites. Aryl-dialkyl-phosphatase which has a prominent role in the metabolism of several toxic, synthetic compounds, may be potentially related to human hepatocarcinoma susceptibility. The biological significance of its differential expression in normal versus malignant tissue is discussed.

Characterization of CPP32-like protease activity following apoptotic challenge in SH-SY5Y neuroblastoma cells

We characterized the activation of interleukin-1beta-converting enzyme (ICE)-like proteases (caspases) in human neuroblastoma cells (SH-SY5Y) following challenge with staurosporine, an established agent known to induce apoptosis. Time course analyses of lactate dehydrogenase release detected a significant increase in cell death as early as 6 h that continued at least until 24 h following staurosporine treatment. Western blot analyses using anti-poly(ADP-ribose) polymerase (anti-PARP) and anti-CPP32 antibodies revealed proteolytic processing of CPP32 (an ICE homologue) as well as fragmentation of PARP as early as 3 h following staurosporine challenge. Furthermore, the hydrolysis of the CPP32 substrate acetyl-DEVD-7-amido-4-methylcoumarin was detected as early as 3 h and became maximal at 6 h after staurosporine challenge, suggesting a delayed and sustained period of CPP32-like activation. In addition, we used the first immunohistochemical examination of CPP32 and PARP in cells following an apoptotic challenge. The localization of CPP32 in untreated SH-SY5Y cells was exclusively restricted to the cytoplasm. Following staurosporine challenge there was a condensing of CPP32 immunofluorescence from the cytoplasm to a region adjacent to the plasma membrane. In contrast, PARP immunofluorescence was evenly distributed in the nucleus in untreated SH-SY5Y cells and on staurosporine challenge was found to be associated with condensed chromatin. It is important that a pan ICE inhibitor [carbobenzoxy-Asp-CH2OC(O)-2,6-dichlorobenzene] was able to attenuate lactate dehydrogenase release and PARP and CPP32 cleavage and altered immunohistochemical staining patterns for PARP and CPP32 following staurosporine challenge.

Reduction of ischemic reperfusion edema with corticotropin-releasing factor (CRF) in rat hind limb replantation

Corticotropin-releasing factor (CRF), a peptide neurotransmitter, is suggested as a novel agent to reduce reperfusion edema following ischemia. In a rat hind limb replantation model, animals underwent amputation followed by 2.5 hours of ischemia with replantation and 2 hours of reperfusion. Animals were randomized to seven groups: a nonischemic control group and six experimental groups receiving treatment prior to reperfusion with (1) saline control, (2) alpha 9,41-CRF-a CRF receptor blocking agent (98 micrograms/per kilogram), (3) subcutaneous CRF (320 micrograms/per kilogram), (4) intravenous CRF (80 micrograms/per kilogram), (5) alpha-CRF and subcutaneous CRF, and (6) alpha-CRF and intravenous CRF. Comparison of preischemic amputated limb weight with weight after ischemia and reperfusion showed a reproducible and significant gain in limb weight after 2 hours (p = 0.004). A significant reduction in limb weight gain (49%) was achieved with both subcutaneous (p < 0.04) and intravenous CRF (p < 0.036). With the dose used in this model, alpha 9,41 CRF attenuated but did not completely block the effects of intravenous or subcutaneous CRF.

The physician and the Internet

The Internet is one of the greatest developments in informational exchange during the past century. It allows almost anyone to access information available throughout the world. Nonetheless, the Internet is often misunderstood by physicians. It can be considered a super computer network that allows users to transfer a wide variety of information at a low cost. The information can be transferred through functions such as electronic mail, file transfer protocols, the Usenet, or the most widely recognized World Wide Web. Electronic mail functions like the usual postal service but is carried through the Internet, and delivery is usually within the hour. It can serve as a method of communication between physicians and patients. File transfer protocols function as a method for transferring large amounts of information such as software through the Internet. The Usenet acts like an international bulletin board service, allowing users anywhere to post messages and to respond to messages from other users. Several patient support groups have Usenet sites for exchanging specific disease information. The World Wide Web has received the greatest attention because most of the information on the Internet is text, sound, or pictures. Numerous medical organizations have established Web sites. This article attempts to describe each of these functions and the benefits to physicians.

Effects of ICE-like protease and calpain inhibitors on neuronal apoptosis

Both ice-like protease and calpain have been shown to be involved in apoptosis in non-neuronal cells. Cultured rat cerebellar granule neurons undergo apoptosis when exposed to low potassium-containing medium. Calpain inhibitors 3-(4-iodophenyl)-2-mercapto-(Z)-2-propenoic acid (PD150606) and N-acetyl-Leu-Leu-Met-CHO (calpain inhibitor II) as well as interleukin-beta 1 converting enzyme (ICE)-like protease inhibitor Z-Asp-CH2OC(O)-2,6-dichlorobenzene (Z-D-DCB) protect against such apoptotic death. They also reduce DNA laddering and the number of apoptotic nuclei. Staurosporine treatment also evokes apoptosis in human neuroblastoma SH-SY5Y. While Z-D-DCB is again anti-apoptotic, calpain inhibitors only provide modest effects in this model. Our results suggest that ICE-like protease plays a critical role in neuronal apoptosis whereas the contributions of calpain are more cell-type dependent.

Non-erythroid alpha-spectrin breakdown by calpain and interleukin 1 beta-converting-enzyme-like protease(s) in apoptotic cells: contributory roles of both protease families in neuronal apoptosis

The cytoskeletal protein non-erythroid alpha-spectrin is well documented as an endogenous calpain substrate, especially under pathophysiological conditions. In cell necrosis (e.g. maitotoxin-treated neuroblastoma SH-SY5Y cells), alpha-spectrin breakdown products (SBDPs) of 150 kDa and 145 kDa were produced by cellular calpains. In contrast, in neuronal cells undergoing apoptosis (cerebellar granule neurons subjected to low potassium and SH-SY5Y cells treated with staurosporine), an additional SBDP of 120 kDa was also observed. The formation of the 120 kDa SBDP was insensitive to calpain inhibitors but was completely blocked by an interleukin 1 beta-converting-enzyme (ICE)-like protease inhibitor, Z-Asp-CH2OC(O)-2,6-dichlorobenzene. Autolytic activation of both calpain and the ICE homologue CPP32 was also observed in apoptotic cells. alpha-Spectrin can also be cleaved in vitro by purified calpains to produce the SBDP doublet of 150/145 kDa and by ICE and ICE homologues [ICH-1, ICH-2 and CPP32(beta)] to produce a 150 kDa SBDP. In addition, CPP32 and ICE also produced a 120 kDa SBDP. Furthermore inhibition of either ICE-like protease(s) or calpain protects both granule neurons and SH-SY5Y cells against apoptosis. Our results suggest that both protease families participate in the expression of neuronal apoptosis.

Esophagitis associated with the use of alendronate

BACKGROUND

Alendronate, an aminobisphosphonate and a selective inhibitor of osteoclast-mediated bone resorption, is used to treat osteoporosis in postmenopausal women and Paget's disease of bone. Aminobiphosphonates can irritate the upper gastrointestinal mucosa.

METHODS

We describe three patients who had severe esophagitis shortly after starting to take alendronate and also analyze adverse esophageal effects reported to Merck, the manufacturer, through postmarketing surveillance.

RESULTS

As of March 5, 1996, alendronate had been prescribed for an estimated 475,000 patients worldwide, and 1213 reports of adverse effects had been received. A total of 199 patients had adverse effects related to the esophagus; in 51 of these patients (26 percent), including the 3 we describe in case reports, adverse effects were categorized as serious or severe. Thirty-two patients (16 percent) were hospitalized, and two were temporarily disabled. Endoscopic findings generally indicated chemical esophagitis, with erosions or ulcerations and exudative inflammation accompanied by thickening of the esophageal wall. Bleeding was rare, and stomach or duodenal involvement unusual. In patients for whom adequate information was available, esophagitis seemed to be associated with swallowing alendronate with little or no water, lying down during or after ingestion of the tablet, lying down during or after ingestion of the tablet, continuing to take alendronate after the onset of symptoms, and having preexisting esophageal disorders.

CONCLUSIONS

Alendronate can cause chemical esophagitis, including severe ulcerations, in some patients. Recommendations to reduce the risk of esophagitis include swallowing alendronate with 180 to 240 ml (6 to 8 oz) of water on arising in the morning, remaining upright for at least 30 minutes after swallowing the tablet and until the first food of the day has been ingested, and discontinuing the drug promptly if esophageal symptoms develop.

Modulation of hypoxia-induced calpain activity in rat renal proximal tubules

The effect of the newly developed, nonpeptide, calpain inhibitor, PD 150606, on hypoxia and ionomycin-induced increases in calpain activity in rat proximal tubules (PT) was determined. PD150606 inhibited both hypoxia and ionomycin-induced calpain activity as determined by the fluorescent substrate N-succinyl-Leu-Leu-Val-Tyr-7-amido-4-methyl coumarin (N-succinyl-Leu-Leu-Val-Tyr-AMC). This decrease in calpain activity was accompanied by dose-dependent cytoprotection against hypoxia and ionomycin-induced cell membrane damage. PD150606 had no effect on cathepsin B and L activity in PT as measured by the fluorescent substrate, benzyloxycarbonyl-L-phenylalanyl-L-arginine-7-amido-4-methyl coumarin (Z-Phe-Arg-AMC). The effects of low intracellular pH (pHi) or low free cytosolic calcium [Ca2+]i on this hypoxia-induced calpain activity were also determined. Both low pHi and low [Ca2+]i attenuated the hypoxia-induced increase in calpain activity. This attenuation of calpain activity was observed early before hypoxia-induced membrane damage and was associated with marked reduction in the typical pattern of hypoxia-induced cell membrane damage observed in this model. To identify the isoform of calpain activated in rat proximal tubules, normoxic, hypoxic and ionomycin treated tubules were fractionated by MONO-Q anion exchange chromatography and the fractions were assayed for calpain activity. A single peak of calpain activity characteristic of mu-calpain was found. The calcium dependency of the calpain activity was in the nanomolar range, further confirming that the activity was the low Ca(2+)-sensitive mu-calpain. The present study suggests that in rat proximal tubules: (1) PD 150606 is a specific inhibitor of calpain and not cathepsins B and L; (2) the cytoprotective effects of low pHi and low [Ca2+]i are mediated, at least in part, by inhibition of calpain activity; and (3) the predominant active form of calpain is the isoenzyme mu-calpain.

Effect of Schwann cells in the enhancement of peripheral-nerve regeneration

Schwann cells appear to stimulate the early phases of axon regeneration. The reported study investigated whether nerve guides with Schwann-cell monolayers can help regenerating nerves span gaps larger than 1 cm. Schwann-cell cultures were established by resecting 1-cm segments of sciatic nerves of adult female Sprague-Dawley rats, establishing cell monolayers in 24-mm nerve guides, and then reinserting these "living guides" into 20-mm nerve gaps of the rats from which they were developed. Control groups had plain guides (no Schwann cells) inserted between the same 20-mm gaps. In the experimental group, resected nerves regrew progressively. At 8 weeks, regrowth had spanned the entire gap in 60 percent of the animals. Axon counts increased at each successive time point. Regeneration did begin to occur in the control group but by 8 weeks, those cables had atrophied. The experimental groups displayed more central connections and higher nerve conduction velocity. Explant organ cultures of rat sciatic nerve can be used to develop nonneural conduits with Schwann-cell monolayers. These living artificial nerve guides permit the spanning of gaps of at least 20 mm.

Phenytoin pretreatment prevents hypoxic-ischemic brain damage in neonatal rats

This study was performed to investigate whether the anticonvulsant phenytoin has neuroprotective effect in a model of hypoxia-ischemia with neonatal rats. The left carotid artery of each rat was ligated, followed by 3 h of hypoxic exposure (8% O2) in a temperature-regulated environment (36 degrees C). Two weeks later, brain damage was assessed by measuring loss of brain hemisphere weight. Phenytoin had no effect on body temperature or plasma glucose, but attenuated brain damage in a dose-dependent manner (3, 10, and 30 mg/kg i.p.) when administered before the hypoxic episode. Phenytoin administered during or after hypoxia did not alter hypoxic brain damage significantly. A parallel experiment using histological examination of frozen brain sections demonstrated less brain infarction after phenytoin treatment (30 mg/kg i.p.). In an additional experiment measuring breakdown of an endogenous brain calpain substrate, spectrin, phenytoin treatment reduced this measure of early cellular damage. Our results indicate that pretreatment with phenytoin is neuroprotective at a plasma phenytoin concentration of approximately 12 micrograms/ml. These results are consistent with the hypothesis that blockade of voltage-dependent sodium channels reduces brain damage following ischemia.

Maitotoxin induces calpain activation in SH-SY5Y neuroblastoma cells and cerebrocortical cultures

Maitotoxin (MTX) is a highly potent marine toxin that activates both voltage-sensitive and receptor-operated calcium channels in the plasma membrane. This results in calcium overload that rapidly leads to cell death. We now report that maitotoxin (0.1-1 nM) induces calpain activation in both SH-SY5Y neuroblastoma cells and fetal rat cerebrocortical cultures. MTX-induced calpain activation was confirmed by the presence of autolytic fragmentation of both subunits of calpain. Secondly, the formation of calpain-produced alpha-spectrin breakdown products (150 and 145 kDa) was observed. We were also able to detect intracellular hydrolysis of a peptide substrate (succinyl-Leu-Leu-Val-Tyr-7-amido-4-methylcoumarin) by activated calpain in MTX-treated cells. Calpain inhibitors (calpain inhibitor I, MDL28170 and PD150606) inhibited spectrin breakdown and SLLVY-AMC hydrolysis in MTX-treated SY5Y cells. Our results suggest that (i) calpain is activated as a result of the maitotoxin-induced calcium influx; and (ii) coupling with the in situ calpain assays, maitotoxin would be a useful tool in investigating the physiologic and pathophysiologic roles of calpain in neuronal cells.

An alpha-mercaptoacrylic acid derivative is a selective nonpeptide cell-permeable calpain inhibitor and is neuroprotective

Overactivation of calcium-activated neutral protease (calpain) has been implicated in the pathophysiology of several degenerative conditions, including stroke, myocardial ischemia, neuromuscular degeneration, and cataract formation. Alpha-mercaptoacrylate derivatives (exemplified by PD150606), with potent and selective inhibitory actions against calpain, have been identified. PD150606 exhibits the following characteristics: (i) Ki values for mu- and m-calpains of 0.21 microM and 0.37 microM, respectively, (ii) high specificity for calpains relative to other proteases, (iii) uncompetitive inhibition with respect to substrate, and (iv) it does not shield calpain against inactivation by the active-site inhibitor trans-(epoxysuccinyl)-L-leucyl-amido-3-methylbutane, suggesting a nonactive site action for PD150606. The recombinant calcium-binding domain from each of the large or small subunits of mu-calpain was found to interact with PD150606. In low micromolar range, PD15O6O6 inhibited calpain activity in two intact cell systems. The neuroprotective effects of this class of compound were also demonstrated by the ability of PD150606 to attenuate hypoxic/hypoglycemic injury to cerebrocortical neurons in culture and excitotoxic injury to Purkinje cells in cerebellar slices.

N-methyl-D-aspartate receptor-induced proteolytic conversion of postsynaptic class C L-type calcium channels in hippocampal neurons

Ca2+ influx controls multiple neuronal functions including neurotransmitter release, protein phosphorylation, gene expression, and synaptic plasticity. Brain L-type Ca2+ channels, which contain either alpha 1C or alpha 1D as their pore-forming subunits, are an important source of calcium entry into neurons. Alpha 1C exists in long and short forms, which are differentially phosphorylated, and C-terminal truncation of alpha 1C increases its activity approximately 4-fold in heterologous expression systems. Although most L-type calcium channels in brain are localized in the cell body and proximal dendrites, alpha 1C subunits in the hippocampus are also present in clusters along the dendrites of neurons. Examination by electron microscopy shows that these clusters of alpha 1C are localized in the postsynaptic membrane of excitatory synapses, which are known to contain glutamate receptors. Activation of N-methyl-D-aspartate (NMDA)-specific glutamate receptors induced the conversion of the long form of alpha 1C into the short form by proteolytic removal of the C terminus. Other classes of Ca2+ channel alpha1 subunits were unaffected. This proteolytic processing reaction required extracellular calcium and was blocked by inhibitors of the calcium-activated protease calpain, indicating that calcium entry through NMDA receptors activated proteolysis of alpha1C by calpain. Purified calpain catalyzed conversion of the long form of immunopurified alpha 1C to the short form in vitro, consistent with the hypothesis that calpain is responsible for processing of alpha 1C in hippocampal neurons. Our results suggest that NMDA receptor-induced processing of the postsynaptic class C L-type Ca2+ channel may persistently increase Ca2+ influx following intense synaptic activity and may influence Ca2+-dependent processes such as protein phosphorylation, synaptic plasticity, and gene expression.

Total protein extraction from cultured cells for use in electrophoresis and western blotting

Experimentation with cultured cells often requires analyzing cellular protein extract by gel electrophoresis and immunoblotting. Traditional methods for extracting cellular proteins by homogenization or detergent solubilization usually produce protein samples that are viscous (due to the presence of DNA) and prone to degradation due to the presence of endogenous protease activity. We have developed a method that involves solubilization of cells with sodium dodecyl sulfate (SDS), precipitation of proteins with trichloroacetic acid (TCA) with special physical exclusion of DNA aggregate and reconstitution of precipitated proteins with Tris base. Protein samples prepared by this method contain little DNA, making them ideal for long-term storage. The solubilized total protein extracts are fully compatible with protein assay, gel electrophoresis and Western blotting. When compared to protein extracts from a homogenization method, those from the TCA method showed an identical total protein staining pattern on SDS polyacrylamide gel electrophoresis and contained distinct cellular proteins recognized by many monoclonal and polyclonal antibodies tested (including anti-actin, spectrin, protein kinase C (alpha), talin and spectrin) on Western blots.

Binding and aggregation of human mu-calpain by terbium ion

Human mu-calpain is activated maximally by 100-200 microM Ca2+. Both the 80 kDa and 29 kDa subunits of mu-calpain have a EF-hand type calcium-binding domain. It is known that trivalent terbium ion (Tb3+) mimics Ca2+ in many biological systems. We found that Tb3+ alone transiently activated calpain. However, in the presence of Ca2+, Tb3+ inhibited mu-calpain with an IC50 of about 100 microM. As high as 10 mM Ca2+ did not significantly shift the IC50 of Tb3+. Preincubating mu-calpain by Ca2+ (before Tb3+ and substrate were added) did not diminish the inhibition by Tb3+. On the other hand, pretreating mu-calpain with Tb3+ produced that Tb3+ has a slow dissociation rate for the calcium-binding sites when compared to Ca2+. Electrophoretic analysis revealed that terbium ion transiently activated mu-calpain followed by the aggregation of the proteinase.

Risk of fetal chromosomal abnormalities in idiopathic polyhydramnios

BACKGROUND

Polyhydramnios is often associated with fetal anatomical abnormalities; thus chromosome analysis is indicated for fetuses with those indications. However, chromosome analysis for patients with idiopathic polyhydramnios is often overlooked. This is an attempt to evaluate the necessity for chromosome analysis in pregnancies with idiopathic polyhydramnios.

METHODS

Genetic amniocentesis or percutaneous umbilical blood sampling was done in 33 cases with idiopathic polyhydramnios which appeared at 26 to 34 weeks' gestation. To exclude false idiopathic polyhydramniotic cases, a level II sonographic examination was carefully performed for those fetuses with abnormal chromosome. Autopsy ultrasound examination and X-ray examination were done in four neonates with abnormal karyotypes, and the results were compared with prenatal sonographic findings.

RESULTS

Seven (21.2%) out of the 33 cases were, surprisingly found to have chromosomal abnormalities. Three out of the seven cases were diagnosed to have fetal anatomical defects, at a repeated level II sono-graphic examination. The incidence of fetal chromosome abnormalities in idiopathic polyhydramnios was 13.3% (4/30). After 7 cases of women older than 34 years and 3 cases with false idiopathic polyhydramnios were excluded, the incidence of chromosomal abnormalities in pregnancies of those under 34 years of age with idiopathic polyhydramnios was 8.3% (2/24).

CONCLUSIONS

According to the results of this study and other papers, the incidence of chromosomal abnormalities in fetuses with idiopathic polyhydramnios is much higher than that for maternal age specific risk at 34 years of age. Therefore fetal chromosome analysis for pregnancies with idiopathic polyhydramnios is recommended to avoid unnecessary Cesarean sections and deliveries of viable babies with abnormal chromosomes.

Diagnosis of foregut duplication cysts by endoscopic ultrasonography

BACKGROUND & AIMS

Foregut duplication cysts are rare congenital anomalies of enteric origin found most commonly in children and rarely in adults. They are usually found in adults on routine radiological studies and represent a challenging diagnostic problem. Conventional imaging tests do not lead to a conclusive diagnosis. With endoscopic ultrasonography, it is possible to distinguish between cystic and solid masses and to accurately establish the location of the cyst in relation to the gastrointestinal wall and to the mediastinum.

METHODS

Seven patients who had endoscopic ultrasonography performed because of differentiation between a cystic or solid mass lesion in the chest or abdomen could not be made with conventional radiological methods are described.

RESULTS

In all patients, a definite diagnosis was established by endoscopic ultrasonography. The diagnosis was confirmed in 2 patients after surgical excision.

CONCLUSIONS

Surgery can be avoided in patients with asymptomatic enteric duplication cysts diagnosed by endoscopic ultrasonography.

Calcium-activated proteases in the bovine parathyroid gland: potential role in degradation of parathyroid hormone to peptide fragments

Our studies suggest that protein kinase C is involved in low calcium (Ca2+)-stimulated secretion of parathyroid hormone (PTH) but not directly in high Ca(2+)-stimulated intracellular degradation of PTH to secreted carboxyl-terminal fragments (C-PTH), an important component of Ca(2+)-regulated PTH secretion. The present study was undertaken to determine the presence of calcium-activated proteases, 84 kDa (micro)-calpain and 80 kDa (milli)-calpain, in the bovine parathyroid, and whether they could degrade PTH to C-terminal fragments. Immunocytochemistry of bovine parathyroid tissue using antibodies raised against bovine heart micro- and milli-calpain detected both isoforms of calpain. Western blotting of total bovine parathyroid cell protein prepared from primary cell cultures confirmed the presence of both isoforms of calpain, demonstrated by specific milli- and micro-calpain bands. Purified bovine PTH (bPTH) was incubated in vitro with human erythrocyte micro-calpain and the cleavage products were separated by reverse-phase HPLC. Eluant fractions were assayed with an RIA with equimolar sensitivity to C-PTH and bPTH, and peak areas integrated. Micro-calpain produced a C-PTH peak from bPTH which co-eluted with the major C-PTH secreted by parathyroid cells in culture. C-PTH production by micro-calpain, expressed as per cent area under the curve, increased from 0% in the absence of either micro-calpain or Ca2+, to 71.5% when a 5:1 molar ratio of bPTH to calpain was used. Amino acid sequencing and analysis of the immunoreactive PTH cleavage products indicated the presence of two fragments of bPTH in the C-PTH peak, bPTH47-48 and bPTH69-84. In summary, both isoforms of calpain are present in the bovine parathyroid and calpains may play a role in the Ca(2+)-dependent degradation of PTH to secreted C-terminal fragments.

Aurintricarboxylic acid is an inhibitor of mu- and m-calpain

Aurintricarboxylic acid (ATA) is an endonuclease inhibitor which has been shown to block apoptotic cell death. We have now demonstrated that ATA is also an inhibitor of the Ca(2+)-activated neutral protease (calpain), a class of cytosolic enzyme that may also be activated during apoptosis. The two major calpain isoforms (mu- and m-calpain) were both inhibited by ATA with IC50's of 22 microM and 10 microM, respectively. The autolysis of purified mu-calpain was prevented by ATA in a concentration-dependent manner. Using casein zymography, it was found that the inhibition of mu-calpain by ATA was reversible. Finally, in a fetal rat cerebrocortical culture model of excitotoxicity, pre- and post-treatment of ATA (50 microM) reduced N-methyl-D-aspartate (NMDA)-induced spectrin breakdown and neuronal death, while application of ATA concurrent to NMDA challenge alone had no effect. This pattern of protection could not be explained by simple NMDA receptor antagonism. We thus propose that the neuroprotective effect of ATA could be in part due to its ability to inhibit calpain.

Casein zymography: a method to study mu-calpain, m-calpain, and their inhibitory agents

A zymographic assay for calpains in nondenaturing casein-containing polyacrylamide gels was developed. Calpain samples were run into the polyacrylamide gels by electrophoresis using a Tris-glycine buffer containing 1 mM EGTA to stabilize calpains. Upon completion of the electrophoresis, the gels were washed and incubated in a calpain activation buffer containing 1-4 mM calcium and 10 mM dithiothreitol for 20-24 h. After staining of the casein gels with Coomassie blue G250, both mu-calpain and m-calpain showed up as clearing bands. The amount of calpain loaded was proportional to the brightness of the clearing band. m-calpain can be easily distinguished from mu-calpain due to its higher mobility in the gel. Irreversible inhibitor (e.g., E64c) or tight-binding calmidazolium-treated mu-calpain remained inactive in the casein zymogram, whereas reversible inhibitor (e.g., calpain inhibitor I) was released from the protease by migration and dilution, lifting its inhibition. Crude homogenate of cultured cells (erythrocytes, Molt-4 and cerebrocortical neurons) or tissue (rat brain) can be directly analyzed for the presence of calpain isoforms despite the presence of endogenous calpastatin. Using this technique, mu-calpain activity in Molt-4 cells was found to decrease progressively with A23187 treatment, as a reflection of autolytic inactivation.

A specific inhibitor of calcium/calmodulin-dependent protein kinase-II provides neuroprotection against NMDA- and hypoxia/hypoglycemia-induced cell death

Calcium/calmodulin-dependent protein kinase-II (CamK-II) is a major neuronal protein which plays a significant role in the cellular process of long-term potentiation (LTP), and vesicular release of neurotransmitters. Here, we show that KN-62, 1-[N,O-bis(5-isoquinolinesulfonyl)-N-methyl-L-tyrosyl]-4- phenylpiperazine, a specific cell-permeable inhibitor of CamK-II substantially protected neurons from (1) acute NMDA toxicity and (2) hypoxia/hypoglycemia-induced neuronal injury in fetal rat cortical cultures. KN-62 did not directly inhibit glutamate, kainate, alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA), glycine, or [piperidyl-3,4-(N)]-(N-[1-(2-thienyl)cyclohexyl]-3,4-piperidine) (TCP) binding to rat brain membranes. Finally, KN-62 significantly reduced cellular calcium accumulation following either NMDA challenge or hypoxia/hypoglycemia insult. Our results show that CamK-II plays a key role in mediating some of the biochemical events leading to cell death following an acute excitotoxic insult.

Endoscopic Nd:YAG laser palliation of malignant duodenal tumors

This study assesses the outcome of 20 patients referred for neodymium: yttrium-aluminum-garnet laser therapy of malignant duodenal tumors between 1984 and 1992. Almost all (95%) of these patients required palliative therapy for gastrointestinal hemorrhage, and nearly half (45%) also had obstructive symptoms. A mean of 3 (range, 1 to 6) laser treatment sessions were required for palliation. Laser therapy eliminated the need for blood transfusions in only 38% of patients. Obstructive symptoms were improved in all patients after laser treatment. Treatment failure could not be predicted on the basis of demographic factors (other than age), tumor characteristics, or transfusion requirements. Survival after laser therapy was 30% at 6 months and 15% at 12 months. Endoscopic neodymium:yttrium-aluminum-garnet laser therapy is a reasonable approach for palliation of malignant tumor obstruction or hemorrhage in selected cases; however, hemorrhage often continues.

Continuous alteration of the internal milieu of a nerve-guide chamber using an osmotic pump and internal exhaust system

The use of non-neural conduits to span gaps in regenerating peripheral nerves has been noted in the literature for many years. An intriguing addition to this so-called entubulation repair method is the continuous instillation of neuronotrophic or growth factors into the lumen of the guide to bathe the regenerating nerve. A model is presented which uses an osmotic pump that supplies a constant, reproducible amount of solution into the lumen of a nerve guide without disrupting the regeneration process.

Hyaluronic acid through a new injectable nerve guide delivery system enhances peripheral nerve regeneration in the rat

The use of non-neural conduits to bridge gaps in peripheral nerves has been noted in the literature for many years. A logical extension of this concept is the introduction of neurotrophic or growth promoting factors into the lumen. We present here an injectable nerve guide that allows percutaneous access to the microenvironment of the regenerating peripheral nerve within the guide's lumen. Hyaluronic acid, a compound associated with decreased scarring and improved fibrin matrix formation, is added sequentially to the regenerating peripheral rat sciatic nerve via this injectable nerve guide. Assessment of nerve regeneration and reinnervation shows better conduction velocity, higher axon counts, and a trend toward earlier myelination with hyaluronic acid compared with saline. This work not only implies hyaluronic acid's role as an agent that aids nerve growth but also describes a new tool that allows percutaneous access to the milieu of a regenerating nerve.

Brunner's gland hamartomas: clinical presentation and pathological features of 27 cases

OBJECTIVES

The aim of this study was to characterize the clinical presentation, pathological features, and outcome of a series of patients with Brunner's gland hamartomas.

METHODS

We reviewed the clinical and pathological features of 27 patients who presented with Brunner's gland hamartomas, and we obtained follow-up information.

RESULTS

Patients (12 men and 15 women) presented predominantly in the fifth and sixth decades of life either with gastrointestinal hemorrhage (n = 10) or obstructive symptoms (n = 10); there were also patients whose tumors were discovered as an incidental finding (n = 7). The tumors were generally pedunculated, were located in the first portion of the duodenum, and were in the range of diameter from 1 to 6 cm. Histologically, the hamartomas were characterized by the presence of nondysplastic, lobulated Brunner's glands with intervening bands of fibrous tissue and variable adipose and lymphoid tissue. Focal sclerosis was found in 93% of the hamartomas, possibly mimicking an adenocarcinoma. Whether managed surgically (24 patients) or endoscopically (three patients), the outcome was uniformly favorable. After a median period of 7-yr-follow-up, no tumors recurred, and no additional morbidity was identified.

CONCLUSIONS

Brunner's gland hamartomas are rare duodenal tumors occurring in middle age that present either with gastrointestinal hemorrhage, obstructive symptoms, or as an incidental finding. Surgical or endoscopic excision is uncomplicated, and the long-term outcome is favorable.

Inside-out vein graft repair compared with nerve grafting for nerve regeneration in rats

The inside-out vein graft is a vein conduit pulled through itself to invert the normal orientation and place the adventitial layer within the lumen of the conduit. Our study compares regeneration of peripheral nerves in the rat through two conduits: inside-out graft of the jugular vein and autogenous nerve graft. In 10 rats, the right jugular vein was harvested, turned inside out, and used to bridge a 10 mm defect created in the right sciatic nerve. The 10 mm nerve segment from the right was then used as a standard nerve graft to bridge a 10 mm gap created in the left sciatic nerve. Rats were sacrificed at 8 and 12 weeks. Regeneration on the inside-out vein graft side showed superior functional results (faster conduction velocities) and improved histological results (greater axon counts) compared with the nerve grafted side. We feel the adventitial surface of the wall of the vein promotes nerve regeneration by providing an environment rich with collagen, laminin, and Schwann cells and promotes increased vascularization of the new nerve.

Apoptosis occurs in lymphoma cells but not in hepatoma cells following ionizing radiation and photodynamic therapy

The aim of this study was to determine the relative role of apoptosis in photodynamically-induced cytotoxicity or radiation-induced cytotoxicity for hepatoma and lymphoma cells. Human hepatoma cells and mouse lymphoma cells were treated with either photodynamic therapy (PDT) or ionizing radiation. Dosimetry studies of immediate cell death following photodynamic therapy in the hepatoma cell line demonstrated second-order kinetics, similar to that seen in the lymphoma cells. No immediate cell death was noted in the hepatoma or lymphoma cells following ionizing radiation, but experiments measuring delayed cell death demonstrated a dose-dependent response. Maximum DNA ladder formation occurred 2 hr after PDT and 24 hr after ionizing radiation in the lymphoma cells, which was consistent with the time courses of cell death for these treatments. The hepatoma cell line did not demonstrate DNA ladder formation despite dosages of PDT or ionizing radiation sufficient to cause high levels of cytotoxicity.

Calpain inhibition: an overview of its therapeutic potential

Increasing evidence now suggests that excessive activation of the Ca(2+)-dependent protease calpain could play a key or contributory role in the pathology of a variety of disorders, including cerebral ischaemia, cataract, myocardial ischaemia, muscular dystrophy and platelet aggregation. In this review, Kevin Wang and Po-Wai Yuen discuss the evidence linking these disorders to calpain overactivation. At present, it is difficult to confirm the exact role of calpain in these disorders because of the lack of potent, selective and cell-permeable calpain inhibitors. However, given the multiple therapeutic indications for calpain, it appears that achievement of selective calpain inhibition is an important pharmacological goal.

Differential proteolysis of the full-length form of the L-type calcium channel alpha 1 subunit by calpain

This study examines the proteolysis of the carboxy terminal domain of the full-length (alpha 1(212)) and truncated (alpha 1(190)) forms of the rabbit skeletal muscle L-type calcium channel alpha 1 subunit by calpain I and calpain II. Although both forms of the alpha 1 subunit show little sensitivity to proteolysis by calpain II, alpha 1(212) is relatively more sensitive than alpha 1(190) to digestion by calpain I, the form of the enzyme regulated by micromolar concentrations of calcium. Calpain I cleaves a 37-kDa fragment from the C-terminus of alpha 1(212) in a time- and concentration-dependent manner and proteolysis is independent of the alpha 1(212) phosphorylation state. This proteolytic cleavage removes the major site of cyclic AMP-dependent phosphorylation from alpha 1(212) and may provide a mechanism for modifying the cyclic AMP-dependent regulation of L-type calcium channels in skeletal muscle.

Does performance status influence the outcome of Nd:YAG laser therapy of proximal esophageal tumors?

The value of endoscopic palliative therapy for malignant obstruction in the proximal esophagus has been questioned. To assess the importance of pre-treatment performance status on treatment outcome, we reviewed the records of patients with tumors of the proximal esophagus undergoing endoscopic laser therapy between January 1986 and December 1988. As compared with 10 patients having a good performance status, eight patients with a poor performance status had a lower frequency of obtaining complete functional relief of dysphagia (14% versus 71%), an increased rate of complications (50% versus 0%), and a shorter median survival time (24 days versus 161 days). We conclude that performance status should be considered in determining the appropriateness of laser therapy in patients with proximal esophageal cancer.

Characterization of a novel high molecular mass protein with peptidase activity purified from the human erythrocyte membrane by calmodulin affinity chromatography

A previously undescribed high molecular mass protein (HMP) from human erythrocyte membranes was solubilized by Triton X-100 and purified on a calmodulin-agarose column in the presence of Ca2+. It was shown to have a native molecular mass of 522-560 kDa, comprised of a single subunit of a molecular mass of 28 kDa (p28). The protein is associated with the lipid bilayer rather than with the cytoskeletal component of the membrane. The purified HMP showed peptidase-hydrolyzing activity toward substrates containing hydrophobic amino acids at the P1 position of the P2-P1 cleavage site. The activity was inhibited by serine proteinase inhibitors (leupeptin, phenylmethansulfonyl fluoride) and chymotrypsin inhibitors in particular (chymostatin, N-tosyl-L-phenylalanine chloromethyl ketone). The enzyme exhibited maximal activity at slightly alkaline pH (7.5-8.5) and at 37 degrees C and was stimulated over a narrow range of SDS concentrations (maximal at 0.05%). HMP was found to cross-react in Western blots with an antibody raised against the rabbit multicatalytic proteinase. The single subunit of HMP therefore contains both the catalytic activity and a sequence necessary for its association into a multimeric complex. The properties of the human erythrocyte membrane HMP described indicate that it is a novel peptidase related to the ubiquitous multicatalytic proteinase.

Immunocytochemistry of skeletal muscle basal lamina grafts in nerve regeneration

The influence on nerve regeneration of the extracellular matrix glycoprotein laminin was studied after sciatic nerve transection in 90 outbred Sprague-Dawley rats. Nerve regeneration through basal lamina grafts was comparable with regeneration through traditional nerve grafts across gaps up to 2.0 cm in length. True axonal regeneration rather than axonal branching was demonstrated by retrograde horseradish peroxidase labeling of nerve cables. Pretreatment of basal lamina grafts with antilaminin antibodies reduced the total number of regenerated axons by 90 percent with a significant decrease of nerve conduction velocity and a significant impairment of walking track patterns. The basement membrane glycoprotein laminin serves a critical role in the regeneration of peripheral nerves through basal lamina grafts.

Endoscopic laser coagulation of radiation-induced mucosal vascular lesions in the upper gastrointestinal tract and proximal colon

Endoscopic laser coagulation effectively controls bleeding from radiation-induced rectal vascular lesions.

OBJECTIVE

To assess the outcome of endoscopic treatment of radiation-induced bleeding due to vascular lesions located proximal to the sigmoid colon.

METHODS

We identified 15 consecutive patients with such proximal radiation enteropathy treated at our Institution with Nd:YAG laser between 1984 and 1991. Ten patients (66%) had gastric and/or small bowel involvement, and five (33%) had colonic involvement with or without more proximal lesions. Bleeding first appeared at a mean of 21.2 +/- 12.5 months after completion of radiotherapy. Mean duration of gastrointestinal bleeding before laser treatment was 7.6 +/- 4.6 months.

RESULTS

After completion of laser therapy, bleeding ceased in nine (60%) patients, decreased in three (20%), and persisted in three (20%). The mean hemoglobin level increased from 8.4 +/- 0.5 g/dl to 10.4 +/- 0.6 g/dl after completion of laser treatments (p < 0.02). The mean number of transfusions per patient per year decreased from 10.5 +/- 2.8 to 0.9 +/- 0.7 (p < 0.01). No treatment-related complications or deaths occurred.

CONCLUSIONS

Endoscopic laser coagulation of radiation-induced mucosal vascular lesions in the upper gastrointestinal tract and proximal colon appears to be safe and, in most cases, effective.

Phosphorylation of connexin-32 by protein kinase C prevents its proteolysis by mu-calpain and m-calpain

Isolated connexin-32s from rat and mouse liver are proteolyzed in vitro by the intracellular Ca(2+)-dependent neutral proteases, mu-calpain and m-calpain, producing a major fragment of 26 kDa. Connexin-26 is not proteolyzed by calpain. Calpain cleaves connexin-32 at its C-terminal end as shown by 125I-calmodulin binding experiments. Connexin-32, but not connexin-26, is phosphorylated by both protein kinase A and protein kinase C in serine residues and the sites of phosphorylation by both kinases remain in the major 26-kDa fragment resulting from calpain proteolysis. Phosphorylation of connexin-32 by protein kinase C, but not by protein kinase A, prevents the proteolytic attack of mu-calpain and m-calpain. Phosphorylation of connexin-32 by protein kinase A and protein kinase C does not prevent its proteolysis by papain, alpha-chymotrypsin, proteinase K, and trypsin.

Endoscopic Nd:YAG laser coagulation of bleeding from radiation proctopathy

Hematochezia from mucosal vascular lesions usually confined to the rectum represents an uncommon but problematic late complication of pelvic radiotherapy. We studied 47 patients with medically refractory hematochezia resulting from radiation-induced rectosigmoid mucosal vascular lesions. All lesions were endoscopically coagulated with Nd:YAG laser. Median duration of hematochezia before laser therapy was 11 months, despite previous medical treatment (98%) or bypass colostomy (6%). Within 3 to 6 months after laser treatment, the number of patients with daily hematochezia fell from 40 (85%) to 5 (11%; p < 0.001), and the median hemoglobin level increased from 9.7 gm/dl to 11.7 gm/dl (p < 0.001). Complications occurred in three patients (6%); no deaths occurred. The condition in six patients (12.8%) was not improved by laser treatment. Two patients (4%) ultimately required surgical treatment for bleeding control. On the basis of symptomatic, hematologic, and endoscopic responses, Nd:YAG laser photocoagulation controlled bleeding from radiation proctopathy in most patients with an acceptably low morbidity. Patients with sigmoid colon involvement responded less favorably. Endoscopic laser photocoagulation should be considered before surgical intervention for treatment of hematochezia from radiation proctopathy.

Oral pulse prednisone therapy after relapse of severe autoimmune chronic active hepatitis. A prospective randomized treatment trial evaluating clinical, biochemical, and lymphocyte subset responses

To assess the efficacy of oral pulse prednisone therapy after relapse of severe autoimmune chronic active hepatitis and to determine the effects of such therapy on serum immunoglobulin G levels and peripheral blood lymphocyte subsets, 16 patients were randomized after relapse to therapy with prednisone 90 mg daily for 5 days each month or conventional daily dose therapy with prednisone in combination with azathioprine. Seven of the eight patients randomized to pulse therapy failed treatment after 1.9 +/- 0.7 months (range, 24 days to 6 months). Treatment failure occurred more commonly (87 vs. 0%, p < 0.01) and remission occurred less frequently (0 vs. 87%, p < 0.01) in patients receiving pulse therapy. The percentage and absolute numbers of circulating CD2 and CD4 cells decreased during relapse, while CD8 and CD20 cell counts were not significantly altered. Pulse therapy was associated with a significant increase in the percentage of CD4 cells and decrease in aminotransferase levels after 5 days. Serum immunoglobulin G levels, however, were not affected by treatment and after 1 month the biochemical findings and lymphocyte subsets were again similar to those at relapse. In contrast, serum immunoglobulin G levels decreased after 14 days of combination therapy and by 1 month the numbers in all lymphocyte subsets were higher than at relapse. We conclude that oral pulse prednisone therapy is ineffective for patients in relapse. The numbers of circulating CD2 and CD4 cells fall during relapse and increase as inflammatory activity subsides during corticosteroid therapy. Combination therapy reverses the biochemical changes and alterations in peripheral blood lymphocyte subsets that accompany relapse.