High-power, high-repetition-rate picosecond optical parametric oscillator for the near- to mid-infrared

A high-repetition-rate, singly resonant optical parametric oscillator based on KTiOAsO(4) and synchronously pumped by a self-mode-locked Ti:sapphire laser is reported. Under the conditions of pump-tuned noncritical type II phase matching, average near-infrared output powers of 403 mW have been generated at a repetition rate of 81 MHz. With the available mirror set, signal tuning over 1.116-1.281 microm and idler tuning over 2.260-3.160 microm are demonstrated for a range of pump wavelengths. Without dispersion compensation, signal (idler) pulses with durations of 1.01-1.03 (1.61-2.91) ps have been obtained for 1.2-ps input pump pulses.

Action of sensory neurons in an experimental at colitis model of injury and repair

The influence of sensory nerves on inflammation and healing was studied in a rat colitis model at different stages of inflammation. Studies were performed in animals with and without ablation of sensory nerves, which was achieved by pretreatment with the neurotoxin capsaicin. Colitis was induced by a rectal enema containing trinitrobenzenesulfonic acid (50 mg/kg) in 50% ethanol. Severity of inflammation was markedly increased 3 and 7 days after induction of colitis in the capsaicin-pretreated group compared with the vehicle group as determined by a macroscopic damage score (at 3 days, 12.0 +/- 0.7 vs. 7.5 +/- 1.5; at 7 days, 12.2 +/- 0.8 vs. 6.5 +/- 0.8; P < 0.05), by histology (ulceration score at 3 days, 82 +/- 12 vs. 40 +/- 11%; at 7 days, 92 +/- 5 vs. 46 +/- 13%; P < 0.05), and by myeloperoxidase activity (at 3 days, 133 +/- 30 vs. 42 +/- 14 U/mg protein; at 7 days, 76 +/- 11 vs. 39 +/- 11 U/mg protein; P < 0.05). There was no significant difference in the severity of colitis 14 and 21 days after induction of colitis between the capsaicin-pretreated group and the vehicle group. These data suggest that, in this model, sensory nerves have an important protective function in the acute and subacute phases of inflammation but do not seem to play a significant role in the later stages of chronic inflammation.

Phase II study of amonafide in the treatment of patients with advanced squamous cell carcinoma of the head and the neck. An Illinois Cancer Center study

Amonafide (nafidimide), a synthetic organic compound with an inhibitory effect on cellular replication, was used in a phase II study conducted by the Illinois Cancer Center in order to assess its efficacy and toxicity in advanced or recurrent squamous cell cancer of the head and neck. Eligible patients had received no more than one prior adjuvant or neoadjuvant chemotherapy, had normal bone marrow, renal and hepatic function, ECOG performance status of 0-2, and bidimensionally measurable disease. Eligible patients were administered amonafide at a starting dose of 300 mg/m2 for five consecutive days every 3 weeks with dose escalation or de-escalation according to established hematologic criteria in the absence of disease progression. Nineteen of 22 entered patients were evaluable for response and all patients were evaluable for toxicity. Eleven of 19 patients achieved stable disease. Median time to progression after start of treatment was 57 days, for the 18 patients for whom the date of progression is known. There were no partial or complete responses. Hematologic toxicity was dose limiting with grade 3-4 neutropenia in 50 percent of patients and 4 deaths associated with neutropenic sepsis. Non-hematologic toxicity was mild to moderate with nausea and vomiting predominating. In this study, amonafide was a myelotoxic, inactive treatment in advanced/recurrent head and neck cancer. Further use in head and neck cancer appears unwarranted.

A phase II clinical trial of echinomycin in metastatic soft tissue sarcoma. An Illinois Cancer Center Study

Echinomycin, a cyclic peptide in the family of quinoxaline antibiotics, was evaluated in patient with metastatic, soft tissue sarcoma not previously treated for metastatic disease. The starting dose of echinomycin was 1,200 mcg/m2 administered intravenously, once weekly x 4, followed by a two-week break. The protocol design called for dose escalation on subsequent cycles of therapy, but because of significant toxicity, dose escalation occurred in only 5 of 25 treatment cycles. Severe nausea and vomiting was the most common toxicity. No clinical responses were observed in the 12 evaluable patients. Echinomycin at this dose and schedule is inactive in metastatic soft tissue sarcoma.

Picosecond Ti:sapphire-pumped optical parametric oscillator based on LiB(3)O(5)

We report a high-repetition-rate, singly resonant optical parametric oscillator based on the nonlinear crystal LiB(3)O(5), which is synchronously pumped by a continuous train of picosecond pulses from a self-mode-locked Ti:sapphire laser. Under temperature-tuned noncritical type I phase matching, total average near-infrared output powers of 90 mW at a repetition rate of 81 MHz have been generated over a signal (idler) tuning range of 1.374-1.530 microm (1.676-1.828 microm). Without dispersion compensation, transform-limited signal pulses with durations of 520-780 fs have been obtained at 1.2 times threshold for 1.8-ps input pump pulses.

Identification of novel peptide antagonists for von Willebrand factor binding to the platelet glycoprotein Ib receptor from a phage epitope library

We have constructed a fusion phage epitope library in the filamentous bacteriophage fuse5. The library was made by inserting a degenerate oligonucleotide which encodes 15 variable amino acids into the NH2-terminal region of the phage gene III protein. This library, containing over 10(7) different epitope bearing phage, has been used in an attempt to identify inhibitors of the von Willebrand factor (vWF)-platelet Glycoprotein Ib interaction. The library was screened with a monoclonal antibody (RG46) that recognizes the GPIb binding domain of vWF (amino acids 445-733). A total of 30 clones falling into 8 classes have been identified that react with the RG46 antibody. Isolates from all 8 classes are positive by immunoblot analysis. The amino acid sequence of the gene III fusion protein from positive clones showed a strong homology to the known RG46 epitope. Peptides identified from the screen were synthesized and used to demonstrate that some of the synthetic peptides exhibited inhibitory activity towards ristocetin induced binding of vWF to the GPIb receptor. Thus, we have demonstrated that screening a fusion phage epitope library with a monoclonal antibody that inhibits vWF binding to the GPIb receptor can be a useful tool not only for mapping antibody recognizing determinants, but also can serve as a source for identifying novel peptides that are antagonists for vWF binding to the platelet GPIb receptor.

High-dose aminothiadiazole in advanced colorectal cancer. An Illinois Cancer Center phase II trial

Thirty-three patients with advanced colorectal carcinoma were entered on a phase II trial of weekly IV aminothiadiazole (175 mg/m2 escalated to 200 mg/m2) with concomitant allopurinol and non-steroidal anti-inflammatory agents (NSAID's). Toxicity was predominantly GI, cutaneous, and chest pain/dyspnea. Twenty-five percent of patients had grade 3 or 4 toxicity. There were no responses in 27 evaluable patients. Median survival was 12 months. Aminothiadiazole, at higher doses than used in previous reports, when given with NSAID's, had no significant activity against large bowel cancer.

Identification of a Src SH3 domain binding motif by screening a random phage display library

A phage display library was constructed in the filamentous bacteriophage fuse5. The library was made by inserting a degenerate oligonucleotide which encodes 15 variable amino acids into the NH2-terminal region of the phage gene III protein. This library, containing over 10(7) different phage, was screened with a glutathione S-transferase (GST) fusion protein containing the Src homology 3 (Src SH3) domain and a protein kinase A phosphorylation site (GST/PKA/Src SH3). A family of proline-rich sequences was isolated following four cycles of enrichment and amplification. Phage containing these sequences were shown to specifically bind to the GST/PKA/Src SH3 protein but not to GST/PKA only. A comparison of the inferred amino acid sequence of the different phage clones revealed a consensus sequence, RPLPXXP, which conforms to a Src SH3 domain binding motif identified independently during an affinity screen of a lambda-lox mouse embryo cDNA library using a 32P-labeled Src SH3 protein fragment as the probe (Y. Ivashchenko, manuscript in preparation). Peptides based upon the 7-amino acid SH3 binding domain core motif displayed strong binding to both the Src and to the Fyn SH3 domains, but failed to bind to the SH3 domain of p21 Ras-GTPase-activating protein (Ras-GAP) and other proteins. We anticipate that further screening of the phage display library will be a useful tool for the rapid identification of additional SH3 domain binding sequences and will also help to establish the essential core motifs that define the specificity of interactions among the diverse proteins containing SH3 domains and those containing SH3 binding motifs.

Protective effect of epidermal growth factor in an experimental model of colitis in rats

BACKGROUND/AIMS

The role of epidermal growth factor (EGF) in the maintenance of mucosal integrity in the lower gastrointestinal tract is unknown. The aim of this study was to determine the effect of EGF in experimental colitis.

METHODS

Colitis was induced with 2,4,6-trinitrobenzenesulfonic acid/ethanol enemas. Rats were pretreated with intraperitoneal administration of recombinant human EGF (600 micrograms/kg) or vehicle 1 hour before induction of colitis and daily thereafter until killed at 8 hours, 48 hours, and 1 week. A separate group received an identical dosage and administration of EGF or vehicle for 1 week with treatment initiated 24 hours after the induction of colitis. Colonic tissue was evaluated macroscopically, histologically, and for myeloperoxidase activity.

RESULTS

Pretreatment with EGF reduced microscopic erosions at 8 and 48 hours by 74% and 54%, respectively (P < 0.05). At 1 week, microscopic ulcerations and myeloperoxidase activity were reduced by 65% in the EGF-pretreated group (P < 0.05). No significant difference in macroscopic injury, histological damage, or myeloperoxidase activity was noted when EGF treatment was initiated after the induction of colitis.

CONCLUSIONS

Systemic EGF administration reduces mucosal damage and inflammation in a trinitrobenzenesulfonic acid/ethanol model of colitis in rats through a mechanism involving mucosal protection.

Comparison of a low-fat, ad libitum complex-carbohydrate diet with a low-energy diet in moderately obese women

This study compared the effect of a low-fat, ad libitum, complex-carbohydrate (LFAL) diet with a low-energy (LE) diet on weight loss over 6 mo in moderately obese women. Weight loss was 4.4 kg in the LFAL (n = 47) and 3.8 kg in the LE (n = 42) participants. The difference was not statistically significant. The LFAL participants decreased percent energy from fat by 13%, increased percent energy from carbohydrate by 11.4%, and reduced energy intake by 1654 kJ. The corresponding values in the LE group were 3.8%, 3.5%, and 1991 kJ, respectively. Changes in fat and carbohydrate energy were significantly different by treatment (P < 0.0001). Palatability, satiety, and quality of life (QOL) improved in the LFAL group but diminished in the LE group. Palatability and QOL changes were significantly different by treatment (P < 0.029 and P < 0.048, respectively). It is concluded that an LFAL diet can result in substantial weight loss and is associated with improved palatability and QOL compared with an LE diet.

The role of the gut in regulating food intake in man

In addition to various psychosocial and metabolic factors, food intake is also influenced by gastrointestinal mechanisms that trigger both the initiation and termination of eating behaviors. Although gastric distension is one of the most obvious signs of "fullness" and clearly plays a role in controlling food intake, its effects are only temporary and are distinct from the feelings of satiety generally associated with a meal. Such postprandial sensations appear to be related to the activation of intestinal chemoreceptors. Other evidence indicates that the release of cholecystokinin and perhaps other transmitters as well may contribute to satiety. Although the stomach probably does not expand or shrink in response to different levels of food intake, nutrient receptors in the small intestine probably do adapt to changes in food intake. Intestinal adaptation also occurs in response to thyroid hormone, insulin, and cortisol as well as to obesity, pregnancy, and illness, which all may have an important bearing on changes in eating behavior in these situations.

Depletion of functional ribosomal RNA operons in Escherichia coli causes increased expression of the remaining intact copies

The synthesis of ribosomal RNA is a complex and highly regulated process. To study this process, we have used deletion-insertions to disrupt sequentially from one to four of the seven rRNA (rrn) operons on the Escherichia coli genome. Inactivation of four rrn operons caused a 2.3-fold increase in the expression of a chloramphenicol acetyl transferase reporter gene fused to the tandem promoters of rrnA and a similar increase in the expression of the trp tRNA gene at the end of rrnC. This reflected enhanced expression of the remaining operons to compensate for having only three intact copies. The elevated expression was caused by an increase in both transcription initiation and RNA polymerase elongation rates specifically on rrn operons and occurred in the absence of changes in the intracellular concentration of ppGpp, suggesting that ppGpp is not involved in the regulation of this phenomenon. We discuss these results in relation to the ribosome feedback inhibition model described by Nomura and coworkers.

Consequences of replication fork movement through transcription units in vivo

To examine the basis for the evolutionary selection for codirectionality of replication and transcription in Escherichia coli, electron microscopy was used to visualize replication from an inducible ColE1 replication origin inserted into the Escherichia coli chromosome upstream (5') or downstream (3') of rrnB, a ribosomal RNA operon. Active rrnB operons were replicated either in the same direction in which they were transcribed or in the opposite direction. In either direction, RNA polymerases were dislodged during replication. When replication and transcription were codirectional, the rate of replication fork movement was similar to that observed in nontranscribed regions. When replication and transcription occurred in opposite directions, replication fork movement was reduced.

Propofol (Diprivan)--a new intravenous anesthetic with applications for outpatient ambulatory surgery

A review of the literature pertaining to propofol (Diprivan) is presented. An overview of the drug's pharmaceutical aspects, pharmacokinetic, and pharmacodynamic properties, as well as its side effect profile are discussed. The qualities of Propofol make it an appealing alternative intravenous anesthetic for outpatient ambulatory surgery.

Researching disability: the way forward

This paper critically examines the individualistic and medicalized assumptions underlying much research on disability. The OPCS surveys of disability, in particular, are examined. Based on the perceptions of disabled people and their organizations, and drawing on a series of seminars on disability research which took place in 1991, an alternative social view of disability is presented and applied to research. It is concluded that the assumptions underlying much disability research, especially when they are translated into practice, are oppressive to disabled people, and that participatory and emancipatory research needs to be developed in order to assist disabled people in their struggle for empowerment.

Phase II trial of fludarabine phosphate for adenocarcinoma of the pancreas. An Illinois Cancer Center study

We have conducted a phase II trial of fludarabine phosphate for advanced measurable adenocarcinoma of the pancreas. The drug was administered every 4 weeks by a daily-times-5 bolus schedule beginning at 20 mg/m2/day. No responses were observed in 20 evaluable patients, 18 of whom were previously untreated. Dose-limiting toxicity was leukopenia, and gastroenterologic side effects were frequent. Life-threatening or fatal renal dysfunction occurred in 3 patients. In this schedule fludarabine phosphate is ineffective against adenocarcinoma of the pancreas and appears to have unpredictable severe renal toxicity.

Definition of an advanced nursing practice role in the NICU: the clinical nurse specialist/neonatal practitioner

We surveyed 655 health professionals affiliated with tertiary level neonatal intensive care units in Canada and the United States to define an expanded role for nurses in neonatology and to determine the educational requirements for the role. The role, comprising advanced clinical practice, educational, research, and administrative responsibilities, is a blend of nurse practitioner and clinical nurse specialist activities. Based on survey findings, a neonatal stream within the existing Master of Health Sciences program at McMaster University was developed. To date, 15 clinical nurse specialists/neonatal practitioners (CNS/NPs) are employed in five neonatal intensive care units in Ontario and other related institutions. A randomized trial to evaluate these individuals is in progress.

Conventional and right precordial ECGs, creatine kinase, and radionuclide angiography in post-traumatic ventricular dysfunction

Right ventricular infarction due to ischemic heart disease can be diagnosed by a right precordial electrogram or by first-pass radionuclide angiography (FPRNA). Prior FPRNA studies have shown that cardiac dysfunction after blunt chest trauma (myocardial contusion) is most often due to right ventricular dysfunction. We hypothesized that right ventricular dysfunction due to ischemic heart disease and myocardial contusion should produce similar ECG changes due to myocyte disruption. The purpose of our study was to evaluate the diagnostic value of the right precordial electrogram in suspected cardiac contusion. Thirty-five patients with suspected myocardial contusion based on mechanism of injury/clinical findings and no history of clinical heart disease were enrolled prospectively. All patients had conventional ECG, right precordial electrogram, and FPRNA studies. Twenty patients had normal cardiac scans (group 1); percentage of myocardial creatine kinase (CK-MB) was measured in 12 of these patients and was less than 5% in 11. Fifteen patients had abnormal cardiac scans (wall motion abnormality and/or decreased right ventricular ejection fraction) (mean, 34% +/- 7% [SD]; normal, greater than 40%) (group 2); percentage of CK-MB was measured in 13 of 15 patients and was less than 5% in all 13. Conventional ECGs and right precordial electrograms in all patients were analyzed for differences in heart rate, PR interval, QRS duration, corrected QT interval, and the axis of the frontal and horizontal plane QRS complex and ST segment. There were no significant differences between group 1 and group 2 patients. No patient with myocardial contusion diagnosed by FPRNA had elevated ST segments in V4R through V6R or a percentage CK-MB of more than 5%.(ABSTRACT TRUNCATED AT 250 WORDS)

Experiences of disabled health and caring professionals

The widespread discrimination against disabled people in most types of employment is well known. It would seem likely, therefore, that disabled people would find it difficult to gain access to the health and caring professions, although many people have argued that their personal experience of disability would be an invaluable asset to the professions and patients alike. By means of semi-structured interviews this study aimed to gain insight into the experiences of people who had been accepted into the health and caring professions despite having a substantial disability. Although most respondents reported either positive or neutral attitudes from colleagues, a sizeable minority had experienced negative attitudes, especially when trying to gain access to training and during training itself. Negative attitudes from patients and clients were, in contrast, exceptionally rare. Most respondents viewed their disability as an advantage rather than a disadvantage in the work context, and although some people were restricted in the specialties they could follow, most could fulfil all of their work obligations.

The role of ductal obstruction on the course of hemorrhagic pancreatitis in the pig

The effect of relieving pancreatic duct obstruction after the onset of hemorrhagic pancreatitis was investigated. Hemorrhagic pancreatitis was produced in 20 pigs by a bile salt-trypsin retrograde injection technique. In half the pigs the pancreatic duct was permanently ligated, and in the other half the ductal obstruction was relieved 2 h after the onset of hemorrhagic pancreatitis. The overall mortality rate was the same in both groups by 24 h. No difference was found between the groups in the gross and microscopic appearance of histological samples taken from the pancreas immediately after death. The biochemical parameters measured to assess the severity of pancreatitis such as calcium, BUN, creatinine, glucose, proteins, and hematocrit did not show any difference between the two groups. The serum amylase level, a measure of ductal obstruction, was less at 24 h and even lower at 48 h in the release group as compared to the non-release group. This difference suggests that the ductal obstruction was relieved, as the amylase levels declined at 24 and 48 h. Hemodynamic variables, including cardiac output, pulmonary artery pressure, pulmonary wedge pressure, central venous pressure, and aortic pressure were followed. No significant difference was found in any of these parameters between the two groups. The absence of any significant differences in hemodynamic status, histopathological findings, and biochemical analysis in our pigs, if translatable to man, does not lend support to early operative intervention in gallstone pancreatitis in the hope that those patients who already have hemorrhagic pancreatitis will benefit from early pancreatic ductal decompression.

Electron microscopic visualization of trp operon expression in Salmonella typhimurium

Transcriptional activity of plasmids carrying wild-type and mutant trp operons was visualized in cell lysates of Salmonella typhimurium. Plasmid and transcription-unit sizes varied with the size of the cloned operon. Following 3-(3-indolyl)acrylic acid derepression, all operons of a particular type exhibited the same high level of transcriptional activity. An estimated 11-14 transcripts must be initiated each minute to maintain the 190-base-pair spacing of RNA polymerases observed on the promoter-proximal half of the wild-type trp operon. A decline in RNA polymerase density was observed on promoter-distal portions of cloned trp operons, which may be attributable to premature transcription termination accompanying translation inhibition due to indolylacrylic acid's interference with normal tryptophanyl-tRNA synthetase activity.

A radiographic study of infant metatarsus adductus treatment by serial casting

Although many papers have been written on metatarsus adductus, few have used radiographic criteria for either the diagnosis of or in determining correction of metatarsus adductus. Most use objective clinical appearance as their sole criteria for diagnosis and correction. This paper establishes radiographic criteria for both the diagnosis and correction of metatarsus adductus.

Cimetidine and tranexamic acid in the treatment of acute upper-gastrointestinal-tract bleeding

We studied the effects of tranexamic acid (an antifibrinolytic agent) and cimetidine on acute upper-gastrointestinal-tract bleeding in a double-blind randomized placebo-controlled trial in 775 patients with hematemesis or melena or both. Mortality was significantly reduced in patients receiving either tranexamic acid (mortality, 6.3 per cent) or cimetidine (7.7 per cent), as compared with patients receiving placebo (13.5 per cent) (P = 0.0092 for tranexamic acid vs. placebo, P = 0.045 for cimetidine vs. placebo). Ninety-nine patients were withdrawn before the code was broken, mainly because their primary illness was considered not to be due to acute upper-gastrointestinal-tract bleeding. Mortality among those withdrawn was high (22 per cent), and their exclusion reduced death rates to 4 per cent in those given tranexamic acid, 8 per cent in those given cimetidine, and 11 per cent in those given placebo (P = 0.0072 for tranexamic acid vs. placebo, P greater than 0.50 for cimetidine vs. placebo). The reduced mortality associated with tranexamic acid was detectable at both participating hospitals and in most of the main subgroups of patients classified according to site of bleeding. However, treatment with this agent was not associated with any decrease in the rate of rebleeding or the need for operation.

Ethanol, the liver, and the gastrointestinal tract

Ethanol is easily absorbed from the intestine and diffuses quickly throughout body water. The bulk of ethanol is metabolized in the liver, where alcohol dehydrogenase, a complex mixture of isoenzymes, oxidizes ethanol to acetaldehyde. Ethanol abuse produces functional and structural changes in the gastrointestinal tract, such as in the stomach, small intestine, liver, and pancreas. Accumulating evidence suggests direct toxicity of ethanol and possibly of acetaldehyde. Fatty liver, alcoholic hepatitis, liver cirrhosis, acute and chronic gastritis, deranged structure and function of the small intestine, acute and chronic pancreatitis, and pancreatic lithiasis are some of the sequelae of ethanol abuse. Recent investigations have enhanced our understanding of the functional and structural changes of the gastrointestinal tract produced by the abuse of ethanol.

Occurrence of occlusive intimal changes in an expanded polytetrafluoroethylene graft

A case report is presented demonstrating pathologic changes in the neointima that formed when a polytetrafluoroethylene (PTFE) graft was placed in a 35 year old white male with severe arteriosclerosis. Representative sections of the patient's artery and graft were taken which demonstrated considerable smooth muscle proliferation in both along with full wall healing in the latter. Partial oclusion of the total length of the PTFE graft by a process similar to that occurring in the patient's own arteriosclerotic arteries was found. The consistency and extent of the involvement (> 10 cm in length) would appear to preclude entities such as neointimal fibrous hyperplasia and may point to another consequence of intimal injury and full wall graft healing which may be an undesirable effect of arteriosclerotic metabolism in the human. It is conceivable that full wall graft healing in an arteriosclerotic individual may have untoward events that need to be further investigated as new graft materials are developed.

Entire left atrial myxoma presenting as a saddle embolus

A case is presented in which a complete left atrial myxoma became detached and lodged in the aortic bifurcation. Shortly after it had been removed the patient suffered cardiac arrest and could not be revived.