In vivo and in vitro effects of different anaesthetics on platelet function

Different effects of thiopental, propofol and sevoflurane on platelets have been reported. Patients undergoing thyroid surgery were anaesthetized with thiopental-fentanyl-sevoflurane (n = 11) or propofol-fentanyl-sevoflurane (n = 9). Platelet aggregation and thromboxane A2 generation were studied at baseline, and at the end of anaesthesia induction and surgery. Dose-response experiments were also performed in vitro with single agents. Thiopental-fentanyl-sevoflurane significantly reduced collagen-induced aggregation by the end of induction, while ADP-induced aggregation and thromboxane generation were unaffected. Propofol-fentanyl-sevoflurane had no effect on platelets. Thiopental dose-dependently inhibited platelets in vitro, while fentanyl or propofol did not. In conclusion, thiopental reduces platelet function both ex vivo and in vitro and propofol might be considered haemostatically safer.     

Minimal model analysis of insulin sensitivity and glucose-mediated glucose disposal in Type 1 (insulin-dependent) diabetic pancreas allograft recipients

Summary Decreased insulin sensitivity and glucose-dependent glucose disposal (glucose effectiveness) have been demonstrated in poorly-controlled Type 1 (insulin-dependent) diabetic patients. We have therefore examined the effects of successful pancreas transplantation that results in long-term physiologic normoglycaemia as measured by insulin sensitivity index and glucose effectiveness in 14 Type 1 diabetic recipients (Group 1) using the Bergman minimal model method. Their results were compared with those of five non-diabetic patients with kidney transplant alone (Group 2) and 10 healthy control subjects (Group 3). Mean plasma glucose levels were indistinguishable in Group 1 when compared to Groups 2 and 3. However, mean basal plasma insulin levels were two-and eight-fold greater in Group 1 (36±6 U/ml) than in Group 2 (17±7 U/ml) and Group 3 (4.5±0.6 U/ml), respectively. Following intravenous glucose (t=0 min) and tolbutamide (t=20), peak incremental insulin levels were significantly (p<0.001) greater in Group 1 vs Groups 2 and 3. Mean insulin sensitivity index was 65% and 50% lower in Group 1 (2.89±0.45) and Group 2 (4.11±1.30), respectively, when compared to GroupS (8.40±1.24×10^–1 min^–1 (U/ml)^–1. In contrast, glucose effectiveness was similar in the three groups (Group 1, 2.48±0.26; Group 2, 2.05±0.21; and Group 3, 2.10±0.17×10^–2·min^–1). We conclude that, despite prednisone-induced insulin resistance, normal glucose tolerance is achieved by hyperinsulinaemia and normalisation of glucose-dependent glucose disposal following pancreas-kidney transplantation in Type 1 diabetic patients.     

Ghrelin and growth hormone secretagogues (GHS): modulation of growth hormone secretion and therapeutic applications

Growth hormone-releasing hormone (GHRH) and somatostatin modulate growth hormone (GH) secretion. A third mechanism was discovered in the last decade, involving the action of growth hormone secretagogues (GHS). Ghrelin, the endogenous ligand of the GHS-receptor, is an acylated peptide mainly produced by the stomach, but also synthesized in the hypothalamus. This compound increases both GH release and food intake. Endogenous ghrelin might amplify the basic pattern of GH secretion, optimizing somatotroph responsiveness to GHRH, activating multiple interdependent intracellular pathways. However, its main site of action is the hypothalamus. In the current paper it is reviewed the available data on the discovery of this peptide, the mechanisms of action and possible physiological roles of the GHS and ghrelin on GH secretion, and finally, the possible therapeutic applications of these compounds.     

Primary Hyperparathyroidism and Negative Tc99 Sestamibi Imaging: To Operate or Not?

Background

The indications for surgery in primary hyperparathyroidism (1HPT) are the same for patients with and without localization on imaging. However, patients with negative imaging may not be referred for surgery or the surgeon may be reluctant to operate. We compare outcomes in patients with negative imaging to those with localization.

Methods

A review of patients who underwent primary operation for 1HPT with a preoperative Tc99 sestamibi I-123 (MIBI) scan was conducted. Imaging, laboratory, operative findings, pathologic findings, and outcomes were used to compare patients with negative scans to those with localization.

Results

A total of 2,681 patients had an operation for 1HPT with preoperative MIBI. MIBI imaging was negative in 136 (5.7 %). The negative MIBI group had a lower calcium (10.9 vs. 11.0?mg/ml, P?=?0.02), phosphorus (2.9 vs. 3.1?mg/dl, P?P?=?0.02) and no difference in parathyroid hormone, 25-OH vitamin D, or bone loss. Multigland resection was higher with a negative scan (32 vs. 13 %, P?P?P?=?0.04) and parathyroid hormone (98 vs. 196?pg/ml, P?=?0.03) than those not cured. Patients with both a negative ultrasound result and negative MIBI had a cure rate of 89 %.

Conclusions

A curative operation is performed at an acceptably lower rate with negative MIBI imaging. A decision for surgery with a negative MIBI finding should consider lower cure rates and symptom severity.     

The relation between sarcomere energetics and the rate of isometric tension relaxation in healthy and diseased cardiac muscle

Journal of Muscle Research and Cell Motility - Full muscle relaxation happens when [Ca2+] falls below the threshold for force activation. Several experimental models, from whole muscle organs and...     

NBAS Variants Are Associated with Quantitative and Qualitative NK and B Cell Deficiency

Purpose

Biallelic pathogenic NBAS variants manifest as a multisystem disorder with heterogeneous clinical phenotypes such as recurrent acute liver failure, growth retardation, and susceptibility to infections. This study explores how NBAS-associated disease affects cells of the innate and adaptive immune system.

Methods

Clinical and laboratory parameters were combined with functional multi-parametric immunophenotyping methods in fifteen NBAS-deficient patients to discover possible alterations in their immune system.

Results

Our study revealed reduced absolute numbers of mature CD56^dim natural killer (NK) cells. Notably, the residual NK cell population in NBAS-deficient patients exerted a lower potential for activation and degranulation in response to K562 target cells, suggesting an NK cell–intrinsic role for NBAS in the release of cytotoxic granules. NBAS-deficient NK cell activation and degranulation was normalized upon pre-activation by IL-2 in vitro, suggesting that functional impairment was reversible. In addition, we observed a reduced number of naïve B cells in the peripheral blood associated with hypogammaglobulinemia.

Conclusion

In summary, we demonstrate that pathogenic biallelic variants in NBAS are associated with dysfunctional NK cells as well as impaired adaptive humoral immunity.