Solution structures of stromelysin complexed to thiadiazole inhibitors.

Unregulated or overexpressed matrix metalloproteinases (MMPs), including stromelysin, collagenase, and gelatinase. have been implicated in several pathological conditions including arthritis and cancer. Small-molecule MMP inhibitors may have therapeutic value in the treatment of these diseases. In this regard, the solution structures of two stromelysin/ inhibitor complexes have been investigated using 1H, 13C, and 15N NMR spectroscopy. Both-inhibitors are members of a novel class of matrix metalloproteinase inhibitor that contain a thiadiazole group and that interact with stromelysin in a manner distinct from other classes of inhibitors. The inhibitors coordinate the catalytic zinc atom through their exocyclic sulfur atom, with the remainder of the ligand extending into the S1-S3 side of the active site. The binding of inhibitor containing a protonated or fluorinated aromatic ring was investigated using 1H and 19F NMR spectroscopy. The fluorinated ring was found to have a reduced ring-flip rate compared to the protonated version. A strong, coplanar interaction between the fluorinated ring of the inhibitor and the aromatic ring of Tyr155 is proposed to account for the reduced ring-flip rate and for the increase in binding affinity observed for the fluorinated inhibitor compared to the protonated inhibitor. Binding interactions observed for the thiadiazole class of ligands have implications for the design of matrix metalloproteinase inhibitors.

Intracranial compliance in infants: evaluation with Doppler US.

PURPOSE: To test graded fontanelle compression during Doppler ultrasound (US) scanning to identify and monitor infants with altered cranial compliance. MATERIALS AND METHODS: An ophthalmodynamometer exerted pressure on the anterior fontanelle during Doppler US scanning of the middle cerebral artery. Sixty examinations were performed in 43 infants--13 full-term and 11 premature healthy control subjects, 10 with increased intracranial volume, and nine with suspected abnormal cranial compliance but without increased intracranial volume. Resistive index (RI) and angle-corrected time-averaged mean velocities (TAV) of blood flow were compared at three different pressures. RESULTS: Baseline RI values in healthy full-term infants were significantly lower than in healthy premature infants and infants with abnormal compliance (P < .05). Values for healthy premature infants and infants with abnormal compliance were indistinguishable (P > .5). Neither RI nor TAV changed significantly in healthy infants, but both changed significantly with compression in infants with abnormal cranial compliance. CONCLUSION: This procedure may be more useful than measurement of RI of the anterior cerebral artery alone to evaluate infants with altered cranial compliance.

Esophageal motor dysfunction years after radiation therapy.

Well-known complications of radiation to the esophagus are acute esophagitis and strictures. Although radiologic studies have demonstrated motor abnormalities after radiation treatment, clinical aspects have not been described adequately, nor have manometric evaluations been reported. Clinical presentation of dysphagia long after treatment also has not been reported. We describe herein three patients who presented with dysphagia years after radiation therapy. Radiographic, endoscopic, histologic, and manometric studies supported our conclusion that these patients suffered from radiation-induced esophageal motor dysfunction. This report indicates the need, in the proper setting, to consider radiation-induced motor dysfunction as a cause of dysphagia even decades after radiation treatment.

Reversible hepatitis associated with diclofenac.

We describe the clinical features, liver histology, and ultrastructure in reversible diclofenac-induced hepatitis and review previous reports of this entity. Although rarely reported, diclofenac hepatitis may be severe, and even fatal. Symptoms, which develop from 1 week to 11 months after starting the drug, include jaundice, pruritus, fever, abdominal pain, nausea, vomiting, and rash. Bilirubin and alkaline phosphatase are mildly elevated, transaminases often markedly so. The nature of the idiosyncratic injury appears variable, some cases having features of a hypersensitivity reaction, most being more suggestive of a toxic metabolic effect. Light microscopy shows a nonspecific hepatitis with portal and lobular activity, and focal hepatocellular injury that may progress to zonal or massive necrosis. The ultrastructural features in our case are typical of drug or toxin injury. This may be of value in distinguishing this entity from other forms of hepatitis, which is important in view of the frequent reversibility of this potentially lethal form of injury.

The effect of calmodulin inhibitors with bleomycin on the treatment of patients with high grade gliomas.

Glioblastoma multiforme is a fatal malignancy of the central nervous system, demanding new methods of treatment. The combination of a calmodulin antagonist with bleomycin has shown synergistic activity in several preclinical models and has been evaluated in a Phase I clinical trial. Since phenothiazines reach high concentrations in the central nervous system, and bleomycin has been reported to have antitumoral activity as well, we studied this combination in a Phase II clinical trial. In addition, we purified calmodulin from normal brain and malignant gliomas to determine its biochemical and pharmacological characteristics. Seventeen patients were entered onto this study and all were evaluable. There were no partial or complete responses. There was one case of fatal pulmonary toxicity in a patient showing an objective tumor response. Otherwise, the treatment was well tolerated. Calmodulin purified from the normal brain and gliomas of patients undergoing resection was identical to each other and to calmodulin prepared from rat cerebrum and glioma. These characteristics included elution from a TSK phenyl high pressure liquid chromatography column, migration on 16% sodium dodecyl sulfate gels, amino acid composition, and inhibition by drugs. Therefore, the failure of this combination therapy was not due to a difference in human glioma calmodulin as compared to previously reported studies with calmodulin from murine sources.

Critical evaluation of the AutoMicrobic system gram-negative identification card for identification of glucose-nonfermenting gram-negative rods.

During a 6-month study we critically evaluated the accuracy of the AutoMicrobic system Gram-Negative Identification Card (Vitek Systems, Inc., Hazelwood, Mo.) in identifying glucose-nonfermenting gram-negative bacilli by testing 419 selected isolates in parallel with a conventional reference method. Of 356 isolates included in the AutoMicrobic system profile, a total of 307 (86.2%) were correctly identified, 36 (10.1%) were not identified, and 13 (3.7%) were misidentified. Fifty-eight of 63 (92%) isolates not included in the profile were correctly reported as "unidentified organisms." Overall, if the first-choice identification was always accepted, only 18 (4.3%) isolates would have been incorrectly reported. When first-choice identifications appended with the special message "questionable biopattern" were rejected, and organisms were screened for characteristic odor and antimicrobial susceptibility before final acceptance of the AutoMicrobic system report, the number of misidentifications was reduced to 5 (1.2%). The average time to identification with the AutoMicrobic system Gram-Negative Identification Card was 15 h. This compares favorably with the 65 h required by the reference method.

Synergistic regulation of fetal rat liver nicotinamide adenine dinucleotide phosphate (reduced form) cytochrome c reductase activity: effects of L-triiodothyronine and hydrocortisone.

The activity of hepatic NADPH cytochrome c reductase, an enzyme important in drug and steroid metabolism, increases rapidly during the perinatal period in rats. However, the regulation of this increase is not well understood. To investigate the role of hormones in the development of NADPH cytochrome c reductase activity, fetal rat livers in organ culture were used in the present study. Explants from 20-day-old fetal rat liver could be maintained for up to 96 h in a serum-free medium with or without added hormones. When the explants were exposed to 50 nM L-T3 for 72 h, they had 74% greater NADPH cytochrome c reductase activity than controls. In contrast, 1 microM hydrocortisone (HC) stimulated reductase activity by only 20%. However, when T3 was added with HC there was a synergistic effect, resulting in a 167% elevation in NADPh cytochrome c reductase activity. The response to T3 plus HC was detectable after 24 h and maximal after 72 h. Control activity rose slightly during the first 48 h in culture and was stable thereafter. Stimulation of reductase activity by T3 was detectable at 0.1 nM, half maximal at 2 nM, and maximal between 10 nM and 100 nM. T4 also stimulated NADPh cytochrome c reductase activity in explants but was only 3-4% as potent as T3. The effect of steroids was specific for glucocorticoids. Neither glucagon nor insulin had any measurable effect on reductase activity. Electron micrographs revealed that hepatic ultrastructure was well preserved for at least 72 h of incubation in the presence or absence of hormones. The data suggest, therefore, that the normal perinatal development of hepatic NADPH cytochrome c reductase activity in rats is regulated at least in part by thyroid hormones acting synergistically with glucocorticoids.