Monitoring C-Peptide Storage and Secretion in Islet β-Cells In Vitro and In Vivo

Human proinsulin with C-peptide–bearing Superfolder Green Fluorescent Protein (CpepSfGFP) has been expressed in transgenic mice, driven by the Ins1 promoter. The protein, expressed exclusively in β-cells, is processed and stored as CpepSfGFP and human insulin comprising only ∼0.04% of total islet proinsulin plus insulin, exerting no metabolic impact. The kinetics of the release of insulin and CpepSfGFP from isolated islets appear identical. Upon a single acute stimulatory challenge in vitro, fractional release of insulin does not detectably deplete islet fluorescence. In vivo, fluorescence imaging of the pancreatic surface allows, for the first time, visual assessment of pancreatic islet insulin content, and we demonstrate that CpepSfGFP visibly declines upon diabetes progression in live lepR^db/db mice. In anesthetized mice, after intragastric or intravenous saline delivery, pancreatic CpepSfGFP (insulin) content remains undiminished. Remarkably, however, within 20 min after acute intragastric or intravenous glucose delivery (with blood glucose concentrations reaching >15 mmol/L), a small subset of islets shows rapid dispossession of a major fraction of their stored CpepSfGFP (insulin) content, whereas most islets exhibit no demonstrable loss of CpepSfGFP (insulin). These studies strongly suggest that there are “first responder” islets to an in vivo glycemic challenge, which cannot be replicated by islets in vitro.     

Uterotonics in elective caesarean delivery: a randomised non-inferiority study comparing carbetocin 20 μg and 100 μg

Postpartum haemorrhage is the leading cause of maternal mortality worldwide and prophylactic uterotonic drug administration after the delivery of the infant is advised. Carbetocin is recommended as an uterotonic, but the minimum effective dose has not been verified. We compared the efficacy of two doses of intravenous carbetocin (20 μg and 100 μg) in women undergoing elective caesarean delivery. This was a randomised, double-blind, non-inferiority study in women at low risk of postpartum haemorrhage. Carbetocin was administered on delivery of the anterior shoulder of the neonate. Uterine tone was assessed by the obstetrician 2 min and 5 min after carbetocin administration according to an 11-point numerical rating scale (0 = atonic uterus and 10 = firm uterus). The primary outcome was uterine tone 2 min after carbetocin administration. The pre-specified non-inferiority margin was 1 point on the 11-point scale. Secondary outcomes included: uterine tone at 5 min; use of additional uterotonics within 24 h; blood loss; and adverse effects. Data were available for 53 women in the carbetocin-20 group and for 55 women in the carbetocin-100 group. The mean (SD) uterine tone at 2 min was 7.5 (1.9) in the carbetocin-20 group and 8.0 (1.5) in the carbetocin-100 group. The lower limit of the one-sided 95%CI for the mean difference was outside the non-inferiority margin (at −1.1; p = 0.11) meaning non-inferiority of carbetocin 20 μg compared with carbetocin 100 μg could not be confirmed. However, the secondary outcome measures of uterine tone at 5 min, blood loss and use of additional uterotonics were similar in both groups.     

In vivo and in vitro study on 5α-reductase activities in Chinese men

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A thermal appraisal of the ablation process in canine aorta in vivo using a 100 μm pulsed Nd-YAG laser

A model has been developed to calculate distal tissue necrosis in vascular tissue after application of a 100 laser pulse from a Nd-YAG laser (5 kW peak pulse power on a 0.13 mm² spot size). The model assumes that the temperature profile in the tissue is proportional to the laser light fluence rate and that the distal tissue necrosis depth is that depth in the tissue where there is a temperature increase of 42 °C minus the etch rate (ablation depth per laser pulse). The fluence rate has been calculated using the diffusion approximation to the radiative transport equation. The tissue optical parameters (absorption and reduced scattering coefficients) have been derived from published data. The etch rate used (10m per pulse) is derived from in vivo experimental results. The model predicts a damage depth varying between 0 and 2.33 mm (mean 1.10 mm) and this is compared with an experimental result (0.77 mm) in dog aorta.     

Interaction of ketamine with μ2 opioid receptors in SH-SY5Y human neuroblastoma cells

Purpose. Ketamine is known to interact with opioid receptors. However, because this agent does not produce opioid-like respiratory depression, it might not interact with μ₂ opioid receptors. Therefore, we have studied the interaction of ketamine with μ₂ opioid receptors expressed in SH-SY5Y cells. Methods. SH-SY5Y cells (passage 70–80) were used to obtain ketamine dose-response curves for inhibition of 0.4 nM [³H][d-Ala²,MePhe⁴,Gly(ol)⁵] enkephalin (DAMGO) binding to μ₂ opioid receptors and of forskolin (1 μM)-stimulated cyclic AMP (cAMP) formation. Results. Ketamine displaced [³H]DAMGO binding in SH-SY5Y cells with a K _i of 12.1 μM. However, this concentrations did not inhibit forskolin-stimulated cAMP formation, although at supraclinical concentrations, significant inhibition was observed with an estimated IC₅₀ of 700 μM. Conclusion. The present study indicates that a clinically relevant concentration of ketamine interacts with μ₂ opioid receptors. However, no agonist activity was observed. Received for publication on September 10, 1998; accepted on January 5, 1999     

Preliminary experience with the 1.32 μm neodymium-YAG laser in the treatment of tracheobronchial malignancy

Endoscopic laser treatment for tracheobronchial malignancy is usually given with the neodymium-YAG laser using the 1.064m output beam. However, recent experimental work suggests that the 1.32m output beam of this laser has more desirable tissue effects. We have now treated 55 patients with the 1.32m Nd-YAG laser (MBB-Medizintechnic) under general anaesthesia, using power settings of 10–20 W and pulse durations of up to 1 s. The indications for treatment were localized airway obstruction in each case. Airway calibre was improved in 46 (84%) patients and this was associated with an improvement in symptoms of cough and breathlessness. Patients with tracheal and carinal obstruction exhibited the most striking clinical improvements with up to four-fold increases in peak expiratory flow. In patients with more peripheral endobronchial obstruction, treatment improved airway calibre less frequently and resulted in a smaller clinical improvement. Of 11 patients with obstruction of a main bronchus and lung collapse, treatment led to partial or complete re-expansion in 10 cases (91%). The 1.32m wavelength allows treatment to be conducted efficiently and safely but at a considerably lower power than is required for the 1.064mwavelength. The ability to use low powers has the apparent advantage of generating only negligible quantities of smoke. Our experience with this new laser system demonstrates its considerable potential in the management of tracheobronchial malignancy.     

“In situ” endografting in the treatment of arterial and graft infections

Objective

Endografts (eg, aortic aneurysm device or covered stent) are increasingly being used to temporize or treat arterial and graft infections in inaccessible areas, in patients with compromised anatomy, or in the presence of active bleeding or rupture. This summary examines the evidence for “in situ” endografting in the treatment these conditions.

Screening Gene Knockout Mice for Variation in Bone Mass: Analysis by μCT and Histomorphometry

Purpose of review

The international mouse phenotyping consortium (IMPC) is producing defined gene knockout mouse lines. Here, a phenotyping program is presented that is based on micro-computed tomography (μCT) assessment of distal femur and vertebra. Lines with significant variation undergo a computer-based bone histomorphometric analysis.

Recent findings

Of the 220 lines examined to date, approximately 15% have a significant variation (high or low) by μCT, most of which are not identified by the IMPC screen. Significant dimorphism between the sexes and bone compartments adds to the complexity of the skeletal findings. The μCT information that is posted at www.bonebase.org can group KOMP lines with similar morphological features. The histological data is presented in a graphic form that associates the cellular features with a specific anatomic group.

Summary

The web portal presents a bone-centric view appropriate for the skeletal biologist/clinician to organize and understand the large number of genes that can influence skeletal health. Cataloging the relative severity of each variant is the first step towards compiling the dataset necessary to appreciate the full polygenic basis of degenerative bone disease.

     

Electrosurgery Induced Damage to Ti-6Al-4V and CoCrMo Alloy Surfaces in Orthopedic Implants In Vivo and In Vitro

Background

Recent observations of specific metal damage patterns on retrieved total joint implants implied a cellular origin and was termed inflammatory cell-induced (ICI) corrosion. Although ICI corrosion continues to present a potential damage source for metallic biomaterials surfaces, an alternate source of some damage patterns may arise from electrosurgery instruments in total joint arthroplasty.

Comparison of 50 μg and 25 μg doses of intrathecal morphine on postoperative analgesic requirements in patients undergoing transurethral resection of the prostate with intrathecal anesthesia

Study ObjectiveTo compare the efficacy of 50 μg and 25 μg doses of intrathecal morphine on postoperative pain in patients undergoing transurethral resection of the prostate (TURP) with low-dose bupivacaine.DesignRandomized, double-blinded study.SettingKonya Hospital.Patients70 ASA physical status I, II, and III patients.InterventionsPatients were randomized to two groups: Group A patients received 5 mg of 0.5% hyperbaric bupivacaine (one mL) and 50 μg of morphine (0.5 mL). Group B patients received 5 mg of 0.5% hyperbaric bupivacaine (one mL) and 25 μg of morphine (0.5 mL).MeasurementsPostoperative pain scores, patient and surgeon satisfaction, and side effects such as emesis, pruritus, and respiratory depression, were recorded.Main ResultsPostoperative pain characteristics were similar between the two groups. Frequency of emesis was similar between the groups, while pruritus was significantly higher in Group A. No antipruritic medication was required in any patient. Patient and surgeon satisfaction was evaluated as good or excellent in both groups.ConclusionsIntrathecal morphine at a dose of 25 μg provides similar postoperative analgesia and less pruritus than the 50 μg dose in patients undergoing TURP.