An Ontario Health (Cancer Care Ontario) Clinical Practice Guideline: Surveillance Strategies in Patients with Stage I, II, III or Resectable IV Melanoma Who Were Treated with Curative Intent

AIMS

To make recommendations on managing the surveillance of patients with stage I, II, III or resectable IV melanoma who are clinically free of disease following treatment with curative intent.

MATERIALS AND METHODS

This guideline was developed by Ontario Health's (Cancer Care Ontario's) Program in Evidence-Based Care and the Melanoma Disease Site Group (including seven medical oncologists, four surgical oncologists, three dermatologists, one radiation oncologist and one patient representative). The MEDLINE, EMBASE, Cochrane Library, PROSPERO databases and the main relevant guideline websites were searched. Internal and external reviews were conducted, with final approval by the Program in Evidence-Based Care and the Melanoma Disease Site Group. The Grading of Recommendations, Assessment, Development and Evaluation approach was followed, and the Modified Delphi method was used.

RESULTS

Based on the current evidence (eight eligible original study papers and four relevant guidelines) and the clinical opinions of the authors of this guideline, the initial recommendations were made. To reach 75% agreement for each recommendation, the Melanoma Disease Site Group (16 members) voted twice and one recommendation was voted on three times. After a comprehensive internal and external review process (including national and international reviewers), 12 recommendations, three weak recommendations and six qualified statements were ultimately made.

CONCLUSIONS

After a systematic review, a comprehensive internal and external review process and a consensus process, the current guideline has been created. The guideline authors believe that this guideline will help clinicians, patients and policymakers make well-informed healthcare decisions that will guide them in clinical melanoma surveillance and ultimately assist in improving patient outcomes.

Corporate social performance in international business

We examine the 2022 JIBS Decade Award article by Ioannou and Serafeim (J Int Bus Stud 43(9):834-864, 2012) and review the literature since 2012 to clarify research developments in corporate social responsibility and corporate social performance (CSP) in the multinational enterprise, articulating key themes, findings and antecedents. We present a general framework that highlights unique traits and processes of CSP for MNEs. To advance scholarly progress, we delineate how new theoretical perspectives, such as organizational identity and strategic choice, can be blended with the IB literature to deepen theorization of the topic. We also discuss how new global dynamics, such as geopolitics, digitization, and activism, may shape CSP strategies and activities for MNEs and how future research can tackle these issues.

COVID-19 and digitalization: The great acceleration

Inspired by burgeoning scholarly interest in the role of digitalization in the COVID-19 pandemic, this paper examines how the COVID-19 pandemic is driving or constraining the digitalization of businesses around the globe. We contend that COVID-19 is "the great accelerator" in fast-tracking the existing global trend towards embracing modern emerging technologies ushering in transformations in lifestyle, work patterns, and business strategies. Thus, COVID-19 has evolved to be a kind of "catalyst" for the adoption and increasing use of digitalization in work organization and the office, alongside presenting foreseen and unforeseen opportunities, challenges, and costs-leading to negative and positive feedback loops. In this article, we develop and advance a conceptual model by linking the different forces for and against digitalization in response to the pandemic. Our analysis indicates that adoption of emerging technologies may be hindered by vested external interests, nostalgia, and employer opportunism, as well as negative effects on employee well-being that undermine productivity, work-life balance, and future of work. Whilst digitalization may bring new opportunities, the process imparts risks that may be hard to mitigate or prepare for. Finally, we draw out the wider theoretical and practical implications of our analysis.

How Do Rapidly Internationalizing SMEs Learn? Exploring the Link Between Network Relationships, Learning Approaches and Post-entry Growth of Rapidly Internationalizing SMEs from Emerging Markets

This article explores learning among rapidly internationalizing small and medium sized enterprises (SMEs) and how this supports the post-internationalization growth and survival of these firms. We utilize a qualitative multiple case study approach of ten information and communication technology (ICT) SMEs from a key emerging market—India. Findings suggest that during the post-entry stage, rapidly internationalizing SMEs use a wide range of internal and external sources of knowledge. External sources of knowledge include peer networks, associations in the same industry, international clients/partners, and international connections developed through trade fairs and trade missions. Internal sources of knowledge such as self-learning, especially from trial-and-error and experiential efforts, were found to enhance product, market and technological knowledge; and consequently aided geographic and product diversification. The findings also indicate that firms use a mix of integrated, vicarious, congenital and experiential learning approaches in their post-entry growth and survival phases. Experiential and congenital learning were found to be facilitated by firms’ internal network sources, whereas external network sources provide an ideal platform for vicarious learning. The study provides new insights into networking and learning by providing evidence that exposure to and connection with diverse types of networks can result in various forms of valuable learning for rapidly internationalizing SMEs, which enhances their post-entry growth.

Inter-Kramers Transitions and Spin-Phonon Couplings in a Lanthanide-Based Single-Molecule Magnet

Spin-phonon coupling plays a critical role in magnetic relaxation in single-molecule magnets (SMMs) and molecular qubits. Yet, few studies of its nature have been conducted. Phonons here refer to both intermolecular and intramolecular vibrations. In the current work, we show spin-phonon couplings between IR-active phonons in a lanthanide molecular complex and Kramers doublets (from the crystal field). For the SMM Er[N(SiMe₃)₂]₃ (1, Me = methyl), the couplings are observed in the far-IR magnetospectroscopy (FIRMS) of crystals with coupling constants ≈ 2-3 cm^-1. In particular, one of the magnetic excitations couples to at least two phonon excitations. The FIRMS reveals at least three magnetic excitations (within the ⁴I_15/2 ground state/manifold; hereafter, manifold) at 0 T at 104, ∼180, and 245 cm^-1, corresponding to transitions from the ground state, M_J = ±15/2, to the first three excited states, M_J = ±13/2, ±11/2, and ±9/2, respectively. The transition between the ground and first excited Kramers doublet in 1 is also observed in inelastic neutron scattering (INS) spectroscopy, moving to a higher energy with an increasing magnetic field. INS also gives complete phonon spectra of 1. Periodic DFT computations provide the energies of all phonon excitations, which compare well with the spectra from INS, supporting the assignment of the inter-Kramers doublet (magnetic) transitions in the spectra. The current studies unveil and measure the spin-phonon couplings in a typical lanthanide complex and throw light on the origin of the spin-phonon entanglement.

Falloff Curves of the Reaction CF3 (+M) → CF2 + F (+M)

The thermal dissociation reaction CF₃ (+Ar) → CF₂ + F (+Ar) was studied in incident and reflected shock waves by monitoring UV absorption signals of the primary dissociation product CF₂. CF₃ radicals were produced by thermal decomposition of CF₃I. Accounting for secondary reactions of F atoms, rate constants for the unimolecular dissociation were derived. Experimental parts of the falloff curves were obtained over the ranges 1544-2106 K and 1.0 × 10^-5 ≤ [Ar] ≤ 9.3 × 10^-5 mol cm^-3. Theoretical modeling allowed for a construction of the full falloff curves connecting the limiting low-pressure rate constants k₀ = [Ar] 2.5 × 10¹⁸ (T/2000 K)^-5.1 exp (-42 450 K/T) cm³ mol^-1 s^-1 with the limiting high-pressure rate constants k_∞ = 1.6 × 10¹⁶ (T/2000 K)^-1.3 exp (-43 250 K/T) s^-1 (center broadening factors of F_cent = 0.25, 0.22, and 0.20 at 1500, 2000, and 2500 K, respectively, were used). The influence of simplifications of falloff expressions and of limiting rate constants on the representation of experimental data is discussed.

Systemic adjuvant therapy for adult patients at high risk for recurrent cutaneous or mucosal melanoma: an Ontario Health (Cancer Care Ontario) clinical practice guideline

Background

Previous versions of the guideline from the Program in Evidence-Based Care (pebc) at Ontario Health (Cancer Care Ontario) recommended that the use of high-dose interferon alfa 2b therapy be discussed and offered to patients with resected cutaneous melanoma with a high risk of recurrence. Subsequently, several clinical trials in patients with resected or metastatic melanoma found that immune checkpoint inhibitors and targeted therapies have a benefit greater than that with interferon. It was therefore considered timely for an update to the guideline about adjuvant systemic therapy in melanoma.

Methods

The present guideline was developed by the pebc and the Melanoma Disease Site Group (dsg). Based on a systematic review from a literature search conducted using medline, embase, and the Evidence Based Medicine Reviews databases for the period 1996 to 28 May 2019, the Working Group drafted recommendations. The systematic review and recommendations were then circulated to the Melanoma dsg and the pebc Report Approval Panel for internal review; the revised document underwent external review.

Recommendations

For patients with completely resected cutaneous or mucosal melanoma with a high risk of recurrence, the recommended adjuvant therapies are nivolumab, pembrolizumab, or dabrafenib-trametinib for patients with BRAF V600E or V600K mutations; nivolumab or pembrolizumab are recommend for patients with BRAF wild-type disease. Use of ipilimumab is not recommended. Molecular testing should be conducted to help guide treatment decisions. Interferon alfa, chemotherapy regimens, vaccines, levamisole, bevacizumab, bacillus Calmette-Guérin, and isolated limb perfusion are not recommended for adjuvant treatment of cutaneous melanoma except as part of a clinical trial.

Experimental and modelling study of the multichannel thermal dissociations of CH3F and CH2F

The thermal unimolecular dissociation of CH₃F was studied in shock waves by monitoring the UV absorption of a dissociation product identified as CH₂F.

Staging and surgical approaches in gastric cancer: a clinical practice guideline

BACKGROUND

Resection is the cornerstone of cure for gastric adenocarcinoma; however, several aspects of surgical intervention remain controversial or are suboptimally applied at a population level, including staging, extent of lymphadenectomy (lnd), minimum number of lymph nodes that have to be assessed, gross resection margins, use of minimally invasive surgery, and relationship of surgical volumes with patient outcomes and resection in stage iv gastric cancer.

METHODS

Literature searches were conducted in databases including medline (up to 10 June 2016), embase (up to week 24 of 2016), the Cochrane Library and various other practice guideline sites and guideline developer Web sites. A practice guideline was developed.

RESULTS

One guideline, seven systematic reviews, and forty-eight primary studies were included in the evidence base for this guidance document. Seven recommendations are presented.

CONCLUSIONS

All patients should be discussed at a multidisciplinary team meeting, and computed tomography (ct) imaging of chest and abdomen should always be performed when staging patients. Diagnostic laparoscopy is useful in the determination of M1 disease not visible on ct images. A D2 lnd is preferred for curative-intent resection of gastric cancer. At least 16 lymph nodes should be assessed for adequate staging of curative-resected gastric cancer. Gastric cancer surgery should aim to achieve an R0 resection margin. In the metastatic setting, surgery should be considered only for palliation of symptoms. Patients should be referred to higher-volume centres and those that have adequate support to manage potential complications. Laparoscopic resections should be performed to the same standards as those for open resections, by surgeons who are experienced in both advanced laparoscopic surgery and gastric cancer management.

Shock wave and modeling study of the reaction CF4 (+M) ⇔ CF3 + F (+M)

The thermal decomposition of CF4 (+Ar) → CF3 + F (+Ar) was studied in shock waves over the temperature range 2000-3000 K varying the bath gas concentration [Ar] between 4 × 10(-6) and 9 × 10(-5) mol cm(-3). It is shown that the reaction corresponds to the intermediate range of the falloff curve. By combination with room temperature data for the reverse reaction CF3 + F (+He) → CF4 (+He) and applying unimolecular rate theory, falloff curves over the temperature range 300-6000 K are modeled. A comparison with the reaction system CH4 (+M) ⇔ CH3 + H (+M) is made.

Real-time head movement system and embedded Linux implementation for the control of power wheelchairs

Mobility has become very important for our quality of life. A loss of mobility due to an injury is usually accompanied by a loss of self-confidence. For many individuals, independent mobility is an important aspect of self-esteem. Head movement is a natural form of pointing and can be used to directly replace the joystick whilst still allowing for similar control. Through the use of embedded LINUX and artificial intelligence, a hands-free head movement wheelchair controller has been designed and implemented successfully. This system provides for severely disabled users an effective power wheelchair control method with improved posture, ease of use and attractiveness.

Controlled trial of immediate endoluminal closure of colon perforations in a porcine model by use of a novel clip device (with videos)

BACKGROUND

Although endoluminal closure of a small perforation of the colon is technically feasible, the outcome of such a closure is unclear.

OBJECTIVE

Our purpose was to evaluate the feasibility and the outcome of endoluminal closure of a small perforation of the colon with a novel clip device, the InScope MultiClip Applier (IMCA), and to assess the number of clips required for successful closure.

DESIGN

Prospective controlled study.

SETTING

University hospital.

ANIMALS

17 pigs.

INTERVENTIONS

A 2-cm full-thickness colon perforation was randomized to 3 groups: control, no closure (n = 4), 2-clip closure (n = 7), and 4-clip closure (n = 6).

MAIN OUTCOME MEASUREMENTS

(1) Technical feasibility of closure, (2) closure time, (3) clinical monitoring for 2 weeks, (4) necropsy (day 14), and (5) healing by a dye leak test and histologic examination.

RESULTS

Endoscopic closure of the colon perforation was technically successful in 12 of 13 animals. A wide gaping hole prevented satisfactory closure in 1 animal. The median time for closure with 2 and 4 clips was 2 and 3 minutes, respectively. Clip closure of perforation prevented clinical sepsis (P = .008) and diminished the risk for fibrinous peritonitis (P = .02 for a single test of hypothesis; however, correction for the multiple testing of data removes this significance) and adhesion formation (P = .008) compared with controls, without any leakage. The outcomes of 2- and 4-clip closure were similar.

CONCLUSIONS

Endoluminal closure of a 2-cm colon perforation with clips is successful in preventing peritonitis and adhesions and it can be accomplished quickly with this novel device. Clip closure at 1-cm intervals is sufficient for successful closure of a 2-cm colon perforation.

To lead or not to lead? Prospective controlled study of emergency nurses' provision of advanced life support team leadership

BACKGROUND AND OBJECTIVES

In many emergency departments advanced life support (ALS) trained nurses do not assume a lead role in advanced resuscitation. This study investigated whether emergency nurses with previous ALS training provided good team leadership in a simulated cardiac arrest situation.

METHODS

A prospective study was conducted at five emergency departments and one nurses' association meeting. All participants went through the same scenario. Details recorded included baseline blood pressure and pulse rate, time in post, time of ALS training, and subjective stress score (1 = hardly stressed; 10 = extremely stressed). Scoring took into account scenario understanding, rhythm recognition, time to defibrillation, appropriateness of interventions, and theoretical knowledge.

RESULTS

Of 57 participants, 20 were ALS trained nurses, 19 were ALS trained emergency senior house officers (SHOs), and 18 were emergency SHOs without formal ALS training. The overall mean score for doctors without ALS training was 69.5%, compared with 72.3% for ALS trained doctors and 73.7% for ALS trained nurses. Nurses found the experience less stressful (subjective stress score 5.78/10) compared with doctors without ALS training (6.5/10). The mean time taken to defibrillate from the appearance of a shockable rhythm on the monitor by the nurses and those SHOs without ALS training was 42 and 40.8 seconds, respectively.

CONCLUSION

ALS trained nurses performed as well as ALS trained and non ALS trained emergency SHOs in a simulated cardiac arrest situation and had greater awareness of the potentially reversible causes of cardiac arrest. Thus if a senior or middle grade doctor is not available to lead the resuscitation team, it may be appropriate for experienced nursing staff with ALS training to act as ALS team leaders rather than SHOs.

Chest radiography and the evaluation of the neonate for congenital heart disease

We assessed the utility of the chest film as a screening tool for term and preterm neonates with suspected structural heart disease. Three independent observers, blinded to patient diagnosis, retrospectively evaluated the initial chest film for each of 128 consecutive neonates with suspected heart disease (gestational age, 23-42 weeks; birth weight, 500-4,621 g) who had undergone both chest radiography and echocardiography. These evaluations were subsequently compared with the results of the respective echocardiograms, read by board-certified pediatric cardiologists blinded to the chest film and chest film interpretation. Kappa statistics demonstrated moderate correlation (0.42-0.48) among different observers in their interpretation of the chest films but poor correlation (0.15-0.34) between chest radiography and echocardiography. The chest film had a low sensitivity for structural heart disease (26-59%), with a negative predictive value of 46-52%. Among neonates less than 2 kg or younger than 35 weeks of gestation, the chest film had still lower sensitivity for detecting heart disease. Despite agreement among observers in chest film interpretation, the chest film does not function as a screening test for neonates with suspected heart disease, particularly in small or premature neonates. In neonates with suspected heart disease, echocardiography should be considered, even in patients with chest films that do not suggest congenital heart disease.

Fyn and Lyn phosphorylate the Fc receptor gamma chain downstream of glycoprotein VI in murine platelets, and Lyn regulates a novel feedback pathway

Activation of platelets by collagen is mediated by the complex glycoprotein VI (GPVI)/Fc receptor gamma (FcR gamma chain). In the current study, the role of 2 Src family kinases, Fyn and Lyn, in GPVI signaling has been examined using murine platelets deficient in one or both kinases. In the fyn(-/-) platelets, tyrosine phosphorylation of FcR gamma chain, phopholipase C (PLC) activity, aggregation, and secretion are reduced, though the time of onset of response is unchanged. In the lyn(-/-) platelets, there is a delay of up to 30 seconds in the onset of tyrosine phosphorylation and functional responses, followed by recovery of phosphorylation and potentiation of aggregation and alpha-granule secretion. Tyrosine phosphorylation and aggregation in response to stimulation by collagen-related peptide is further attenuated and delayed in fyn(-/-)lyn(-/-) double-mutant platelets, and potentiation is not seen. This study provides the first genetic evidence that Fyn and Lyn mediate FcR immune receptor tyrosine-based activation motif phosphorylation and PLC gamma 2 activation after the ligation of GPVI. Lyn plays an additional role in inhibiting platelet activation through an uncharacterized inhibitory pathway. (Blood. 2000;96:4246-4253)

Edema volume, not timing, is the key to success in lymphedema treatment

BACKGROUND

There are currently between 1 and 2 million breast cancer survivors in the United States. Is the advocated, early intervention the key to successful treatment, or are there other, more important factors?

METHODS

Responses to combined decongestive therapy (CDT) for 69 women were analyzed with regard to duration of lymphedema, differences in arm circumference, percent differences in arm volumes, volume of edema, reduction of edema volumes, and duration of treatment.

RESULTS

Two- and three-dimensional (2D and 3D) analyses showed little correlation between duration and volume of edema or between duration and response and treatment. However, they did show a correlation between initial volumes of fluid in the tissues and responses. Patients with initial volumes of 250 mL or less had a mean reduction of 78% with CDT, whereas those with initial volumes between 250 and 500 mL had a mean reduction of 56%.

CONCLUSION

The key to predicting successful lymphedema treatment is the initial volume of edema in the tissues regardless of whether the intervention is early or late.

Electron-immunocytochemical studies of perivascular nerves of mesenteric and renal arteries of golden hamsters during and after arousal from hibernation

Electron immunocytochemistry was used to examine perivascular nerves of hamster mesenteric and renal arteries during hibernation and 2 h after arousal from hibernation. Vessels from cold-exposed but nonhibernating, and normothermic control hamsters were also examined. During hibernation the percentage of axon profiles in mesenteric and renal arteries that were immunopositive for markers of sympathetic nerves, tyrosine hydroxylase (TH) and neuropeptide Y (NPY), were increased 2-3 fold compared with normothermic and cold control animals. This increase was reduced markedly only 2 h after arousal from hibernation. The small percentage of nitric oxide synthase-1-positive axon profiles found in mesenteric (but not renal) arteries was also increased during hibernation and returned towards control values after arousal. In contrast, the percentage of perivascular axons immunostaining for vasoactive intestinal polypeptide (VIP), a marker for parasympathetic nerves, was reduced in mesenteric arteries during hibernation. There was no labelling of perivascular nerves for substance P in either mesenteric or renal arteries. It is suggested that the increase in percentage of TH- and NPY-immunostained perivascular nerves may account for the increased vasoconstriction associated with high vascular resistance that is known to occur during hibernation. The reduction in the percentage of axons positive for VIP in hibernating animals would contribute to this mechanism since this neuropeptide is a vasodilator.

Ultrastructural localization of nitric oxide synthase and endothelin in the renal and mesenteric arteries of the golden hamster: differences during and after arousal from hibernation

This is a study of the electron-immunocytochemical localization of nitric oxide synthase (type III) and endothelin in renal and mesenteric artery endothelial cells of normal (active) and hibernating hamsters, as well as hamsters exposed to the cold but not hibernating, and hamsters aroused for 2h following hibernation. In the renal artery of hibernating hamsters and cold-exposed hamsters, a subpopulation of nitric oxide synthase-positive endothelial cells displayed immunoprecipitate predominantly in the vicinity of the Golgi complex indicating intracellular translocation from the cytoplasm to the Golgi complex. In hibernating animals, the percentages of both nitric oxide synthase-positive and endothelin-positive endothelial cells were notably lower than those observed either in active, cold-exposed or aroused animals. These changes may reflect a reduced endothelial contribution to the maintenance of vascular tone in these vessels during hibernation and an upregulation of expression of nitric oxide synthase and endothelin in the endothelium early on during arousal from hibernation.

Children's behaviour and the design of school furniture

Children spend a large part of their school days in the classroom, and yet the effect of the design of school furniture on their behaviour and health has received comparatively little attention in the UK. An experimental study is reported that compares the effects on children's behaviour and sitting position of traditional classroom furniture with a recently designed chair known as 'Chair 2000' and associated tables. It was found that children showed a modest but significant improvement in on-task behaviour and a marked change in sitting positions following the introduction of the newly-designed furniture. However, these benefits need to be considered in the light of polarized opinion for and against the new furniture, and a high level of reported incidence of back pain significantly related to the frequency of non-standard sitting. In the absence of radically redesigned furniture, it is suggested that children should be given more choice in their seating, and better guidance should be given to individuals involved in education in order to inform their decision-making about classroom furniture and the postural, anthropometric and orthopaedic aspects of sitting and related activities.

Effects of hibernation and arousal from hibernation on mesenteric arterial responses of the golden hamster

The aim of our study was to investigate the changes that occur in functional responses of the golden hamster mesenteric arterial bed after: 1) 8 wk of hibernation and 2) 2 hr after arousal from hibernation. Age-matched and cold-exposed hamsters were used as controls. At 8 wk after hibernation there was an increase in sensitivity of vasoconstrictor responses to sympathetic nerve stimulation but no significant difference in constrictor responses to norepinephrine, alpha,beta-methylene ATP, uridine 5'-triphosphate or KCl (studied in unconstricted preparations), or in endothelium-dependent vasodilatation to acetylcholine and uridine 5'-triphosphate (in methoxamine-preconstricted preparations) compared with the control groups. In contrast, in the arousal from hibernation group, sympathetic vasoconstriction was similar to that in the control groups, and the maximal response to exogenous norepinephrine, and responses to alpha,beta-methylene ATP were augmented. These results suggest that there is an augmentation of sympathetic neurotransmission of golden hamster mesenteric arteries at 8 wk after hibernation, which appears to be due to pre- rather than postjunctional changes. This is reversed with arousal from hibernation, when the sensitivity of sympathetic contractile responses is not different from that of the controls. However, an increase in maximal constrictor responses to norepinephrine suggests that postjunctional changes may occur in sympathetic neurotransmission during arousal.

Enhanced vasoconstrictor responses in renal and femoral arteries of the golden hamster during hibernation

1. The present study assessed local regulation of vascular tone of euthermic (control), cold control and hibernating golden hamsters. Sympathetic neurotransmission in the renal artery, the long term effects of hibernation on perivascular nerve activity, and the responsiveness of femoral artery to a number of neurotransmitters and hormones with both constrictor and dilator actions during hibernation are described. 2. The contractile responses of the renal arterial rings to transmural nerve stimulation (80 V, 0.1 ms, 4-64 Hz, for 1 s) were negligible in controls, significantly increased at higher frequencies of stimulation in cold controls and markedly enhanced in the hibernating group at all frequencies tested. The contractile responses to exogenous noradrenaline (NA; 0.1-100 microM) were significantly increased in the renal arteries of hibernating hamsters compared with controls, but not compared with cold controls. Responses to exogenous ATP (1-3000 microM) and KCl (120 mM) were similar among all experimental groups. 3. The maximal contractile responses of femoral arterial rings to the sympathetic co-transmitter ATP and 5-hydroxytryptamine were increased by approximately 124% and 99%, respectively, in hibernating compared with cold control preparations without a change in the concentration of agonist that produces half-maximal response. However, the responses to NA were not altered during hibernation. 4. Vasoconstriction of femoral arterial rings in response to arginine vasopressin was significantly enhanced in both cold controls and hibernating groups, while vasoconstriction in response to endothelin-1 and KCl was unaltered. 5. The dilator responses of femoral arterial rings to acetylcholine, sodium nitroprusside and adenosine were not different among the groups. 6. It is suggested that the marked augmentation of sympathetic neurotransmission, selective supersensitivity of the vascular smooth muscle to sympathetic contractile agents and unaltered vasodilatory mechanisms may provide a means for maintenance of vascular tone and peripheral resistance during hibernation.

Effects of hibernation on neural and endothelial control of mesenteric arteries of the golden hamster

The effects of hibernation on mesenteric arterial innervation and function were examined using pharmacological and immunohistochemical techniques in age-matched controls, cold-exposed controls, and 4-wk-hibernated golden hamsters. Electrical field stimulation of the isolated mesenteric arterial bed elicited frequency-dependent vasoconstriction. The sensitivity of responses was significantly increased in tissues from hibernating animals compared with cold-exposed controls. Vasoconstrictor responses to exogenous norepinephrine were also increased in hibernation. However, there was a significant decrease in sensitivity of vasoconstriction to ATP in hibernated and cold-exposed tissue compared with age-matched controls. In preparations preconstricted with methoxamine, endothelium-dependent vasodilator responses to acetylcholine and ATP were similar among the groups. Immunohistochemical investigation of mesenteric arteries revealed no differences among the groups in density of innervation by nerves immunoreactive for tyrosine hydroxylase, neuropeptide Y, and calcitonin gene-related peptide. Postjunctional changes appear to occur in hibernation, leading to augmentation of sympathetic vasoconstriction, which is consistent with the increase in peripheral vascular resistance in hibernation. Endothelium-dependent vasodilatation is not significantly changed in hibernation in the hamster mesenteric arterial bed.

Neurochemical coding in the myenteric plexus of the upper gastrointestinal tract of hibernating hamsters

As part of our investigation of the plasticity of autonomic nerves in physiological and pathological conditions, we have examined the effect of hibernation on the neurochemical content of myenteric nerves and nerve cell bodies of the upper gastrointestinal tract of the non-seasonal hibernator, the golden hamster. Age matched hamsters kept at room temperature and those kept at 5 degrees C but which failed to hibernate, were used as controls. Possible changes in nerve fibres and nerve cell bodies containing the general neuronal marker, protein gene product 9.5, the peptides, vasoactive intestinal polypeptide, substance P (SP) and calcitonin gene-related peptide (CGRP), the catecholamine synthesizing enzyme tyrosine hydroxylase and the enzyme responsible for synthesizing nitric oxide, nitric oxide synthase, were examined in the oesophagus, proventriculus and proximal and distal stomach of the golden hamsters using immunohistochemical techniques. The results of the present study revealed a significant increase in the number of nerve cell bodies and density of nerve fibres containing SP-immunoreactivity and increased number of CGRP-immunoreactive cell bodies but not the other markers examined in the proximal stomach and proventriculus. In contrast, there was no change in the distribution of any of the neuroactive substances examined in the myenteric plexus of the oesophagus and distal stomach. It is suggested that the change in the environment of the hibernating hamsters perturbs the normal digestive physiology in the proximal stomach and proventriculus that is reflected by the selective changes in SP- and CGRP-containing enteric nerves; these changes may be part of protective reflex mechanisms to the environmental changes resulting from hibernation, where upgrading of nerve cell bodies expressing CGRP and SP has occurred.

Validation of a high-performance liquid chromatographic assay method for pharmacokinetic evaluation of busulfan

The development and validation of a high-performance liquid chromatographic (HPLC) assay for determination of busulfan concentrations in human plasma for pharmacokinetic studies is described. Plasma samples containing busulfan and 1,6-bis(methanesulfonyloxy)hexane, and internal standard, were prepared by derivatization with sodium diethyldithiocarbamate (DDTC) followed by addition of methanol and extraction with ethyl acetate. The extract was dried under nitrogen and the samples reconstituted with 100 microl of methanol prior to HPLC determination. Chromatography was accomplished using a Waters NovaPak octadecylsilyl (ODS) (150 x 3.9 mm I.D.) analytical column, NovaPak ODS guard column, and mobile phase of methanol-water (80:20, v/v) at a flow-rate of 0.8 ml/min with UV detection at 251 nm. The limit of detection was 0.0200 microg/ml (signal-to-noise ratio of 6) with a limit of quantitation (LOQ) of 0.0600 microg/ml for busulfan in plasma. Calibration curves were linear from 0.0600 to 3.00 microg/ml in plasma (500 microl) using a 1/y weighting scheme. Precision of the assay, as represented by C.V. of the observed peak area ratio values, ranged from 4.41 to 13.5% (13.5% at LOQ). No day-to-day variability was observed in predicted concentration values and the bias was low for all concentrations evaluated (bias: 0 to 4.76%; LOQ: 2.91%). The mean derivatization and extraction yield observed for busulfan in plasma at 0.200, 1.20 and 2.00 microg/ml was 98.5% (range 93.4 to 107%). Plasma samples containing potential busulfan metabolites and co-administered drugs, which may be present in clinical samples, provided no response indicating this assay procedure is selective for busulfan. This method was used to analyze plasma concentrations following administration of a 1 mg/kg oral busulfan dose.

The molecular chaperone alpha-crystallin inhibits UV-induced protein aggregation

Solutions of gamma-crystallin, and various enzymes, at neutral pH and 24-26 degrees C, became turbid upon exposure to UV radiation at 295 or 308 nm. SDS-PAGE analysis revealed interchain cross-linking and aggregate formation compared to dark control solutions as reported previously. When alpha-crystallin was added to the protein solutions in stoichiometric amounts, UV irradiation resulted in significantly less turbidity than in the absence of alpha-crystallin. For example, addition of 0.5 mg of alpha-crystallin to 0.5 mg of gamma-crystallin in 1.0 ml solution yielded only 25% of the turbidity seen in the absence of alpha-crystallin. Addition of 2.0 mg of alpha-crystallin resulted in 20% of the turbidity. Given the molecular weights of alpha- and gamma-crystallin (about 800 kDa and 20 kDa, respectively), a gamma/alpha 1:1 weight ratio corresponds to a 40:1 molar ratio, and a gamma/alpha 1:4 weight ratio corresponds to a 10:1 molar ratio. Hence, the molar ratio of alpha-crystallin needed to effectively protect gamma-crystallin from photochemical opacification was gamma/alpha = n:1, where n was in the range 10-40. In terms of subunits, this ratio is gamma/alpha = 1:m, where m = 1-4. Thus, each gamma-crystallin molecule needs 1-4 alpha subunits for protection. Similar stoichiometries were observed for protection of the other proteins studied. The protection stems in part from screening of UV radiation by alpha-crystallin but more importantly from a chaperone effect analogous to that seen in thermal aggregation experiments.

Biochemical characterization of human collagenase-3

The cDNA of a novel matrix metalloproteinase, collagenase-3 (MMP-13) has been isolated from a breast tumor library (Freije, J. M. P., Dicz-Itza, I., Balbin, M., Sanchez, L. M., Blasco, R., Tolivia, J., and López-Otin, C. (1994) J. Biol. Chem. 269, 16766-16773), and a potential role in tumor progression has been proposed for this enzyme. In order to establish the possible role of collagenase-3 in connective tissue turnover, we have expressed and purified recombinant human procollagenase-3 and characterized the enzyme biochemically. The purified procollagenase-3 was shown to be glycosylated and displayed a M(r) of 60,000, the N-terminal sequence being LPLPSGGD, which is consistent with the cDNA-predicted sequence. The proenzyme was activated by p-aminophenylmercuric acetate or stromelysin, yielding an intermediate form of M(r) 50,000, which displayed the N-terminal sequence L58EVTGK. Further processing resulted in cleavage of the Glu84-Tyr85 peptide bond to the final active enzyme (M(r) 48,000). Trypsin activation of procollagenase-3 also generated a Tyr85 N terminus, but it was evident that the C-terminal domain was rapidly lost, and hence the collagenolytic activity diminished. Analysis of the substrate specificity of collagenase-3 revealed that soluble type II collagen was preferentially hydrolyzed, while the enzyme was 5 or 6 times less efficient at cleaving type I or III collagen. Fibrillar type I collagen was cleaved with comparable efficiency to the fibroblast and neutrophil collagenases (MMP-1 and MMP-8), respectively. Unlike these collagenases, gelatin and the peptide substrates Mea-Pro-Leu-Gly-Leu-Dpa-Ala-Arg-NH2 and Mca-Pro-Cha-Gly-Nva-His-Ala-Dpa-NH2 were efficiently hydrolyzed as well, as would be predicted from the similarities between the active site sequence of collagenase-3 (MMP-13) and the gelatinases A and B. Active collagenase-3 was inhibited in a 1:1 stoichiometric fashion by the tissue inhibitors of metalloproteinases, TIMP-1, TIMP-2, and TIMP-3. These results suggest that in vivo collagenase-3 could play a significant role in the turnover of connective tissue matrix constituents.