Peri-operative continuation of metformin does not improve glycaemic control in patients with type 2 diabetes: A randomized controlled trial.

Historically, metformin was withheld before surgery for fear of metformin-associated lactic acidosis. Currently, however, this risk is deemed to be low and guidelines have moved towards the continuation of metformin. We hypothesized that continuing metformin peri-operatively would lower postoperative serum glucose level without an effect on plasma lactate levels. We performed a single-blind multicentre randomized controlled trial in people with type 2 diabetes mellitus scheduled for non-cardiac surgery and continued (MF+ group) or withheld (MF- group) metformin before surgery. The main outcome measures were the differences in peri-operative plasma glucose and lactate levels. We randomized 70 patients (37 MF+ group and 33 MF- group) with type 2 diabetes mellitus. Postoperative glucose levels were similar in the MF+ and the MF- groups (8.2 ± 1.8 vs 8.3 ± 2.3 mmol/L P = .95) Although preoperative lactate levels were slightly higher in the MF+ group compared with the MF- group (1.5 vs 1.2 mmol/L; P = .02), the postoperative lactate levels were not significantly different (1.2 vs 1.0 mmol/L; P = .18). In conclusion, continuation of metformin during elective non-cardiac surgery does not improve glucose control or raise lactate levels to a clinically relevant degree.

The influence of force feedback and visual feedback in grasping tissue laparoscopically.

BACKGROUND: Due to the limited force feedback provided by laparoscopic instruments, surgeons may have difficulty in applying the appropriate force on the tissue. The aim of this study was to determine the influence of force feedback and visual feedback on the exerted pinch force. METHODS: A grasper with a force sensor in the jaws was developed. Subjects with and without laparoscopic experience grasped and pulled pig bowel with a force of 5 N. The applied pinch force was measured during tasks of 1-s and 1-min duration. Visual feedback was provided in half the measurements. Force feedback was adjusted by changing the mechanical efficiency of the forceps from 30% to 90%. RESULTS: The mean pinch force applied was 6.8 N (+/-0.5), whereas the force to prevent slippage was 3.0 N (+/-0.4). Improving the mechanical efficiency had no effect on the pinch force for the 1-s measurements. The amount of excessive pinch force when holding tissue for 1 min was lower at 30% mechanical efficiency compared with 90% (105% vs 131%, p = 0.04). The tissue slipped more often when the subject had no visual feedback (2% vs 8%, p = 0.02). CONCLUSION: Force feedback and visual feedback play a more limited role than expected in the task of grasping tissue with laparoscopic forceps.

Continuous brachial plexus block at the cervical level using a posterior approach in the management of neuropathic cancer pain.

BACKGROUND AND OBJECTIVES: Neuropathic cancer pain due to tumor growth near the brachial plexus is often treated with a combination of nonsteroidal anti-inflammatory drugs, tricyclic antidepressants, anticonvulsants, and oral or transdermal opioids. We propose placement of a catheter along the brachial plexus using a posterior approach for patients not responding to the above-mentioned treatment. CASE REPORT: We describe 2 patients with neuropathic cancer pain in the arm and shoulder despite treatment with dexamethasone, amitriptyline, gabapentin, opioids, and, in 1 patient, oral ketamine. An increase in daily opioid dosage did not relieve the pain but caused unacceptable side effects of nausea, vomiting, and sedation. Continuous administration of local anesthetics via a brachial plexus catheter inserted at the cervical level using a posterior approach resulted in a markedly improved analgesia and decreased opioid requirement. CONCLUSION: Continuous brachial plexus block should be considered in patients with severe neuropathic cancer pain in the arm and shoulder. To achieve sufficient pain relief for prolonged periods of time, a catheter was inserted to block the brachial plexus using a posterior approach. This technique may be a valuable alternative to the interscalene approach because of the improved fixation of the catheter in the muscle sheet of the trapezius, splenius cervicus, and levator scapulae muscles, and the decreased likelihood of catheter dislodgment during neck movements.

Diagnosing genital ulcer disease in a clinic for sexually transmitted diseases in Amsterdam, The Netherlands.

The most common etiologic agents of genital ulcer disease (GUD) are herpes simplex virus type 1 (HSV-1), HSV-2, Treponema pallidum, and Haemophilus ducreyi. In an outpatient clinic for sexually transmitted diseases in Amsterdam, The Netherlands, specimens from 372 patients with GUD were collected from February to November 1996. Sera were collected at the time of the symptoms and, for most patients, also during follow-up visits. Swabs in viral transport medium were used for HSV culture and for detection of DNA. The most prevalent pathogen found was HSV-2, which was detected by culture in 35% of the patients and by PCR in 48% of the patients. Also, HSV-1 infection was more often detected by PCR (7.8%) than by culture (5.6%). Evidence for an active infection with T. pallidum was found in 1.9% of the patients, using serological tests. A multiplex PCR for simultaneous T. pallidum and H. ducreyi DNA detection was positive for T. pallidum in 3.3% of the samples and for H. ducreyi in only 0.9% (3 out of 368) of the samples. The sensitivity of the PCR was superior to that of culture for HSV detection and to that of serology for T. pallidum detection. Specific H. ducreyi immunoglobulin G antibodies were detected in sera of 5.2% of the patients, with no concordance between serology and PCR. In 37% of the cases, none of the tested microorganisms was detected. Performance of PCR in addition to conventional techniques significantly improved the diagnosis of GUD.

Diesel exhaust, carbon black, and silica particles display distinct Th1/Th2 modulating activity.

Certain particulate air pollutants may play an important role in the increasing prevalence of respiratory allergy by stimulating T helper 2 cell (Th2)-mediated immune responses to common antigens. The study described here examined different particles, diesel exhaust particles (DEP), carbon black particles (CBP), and silica particles (SIP) for their immunomodulating capacity in both primary and secondary immune responses in female BALB/C mice. The primary response was studied after subcutaneous injection of 1 mg of particle together with 10 microgram of reporter antigen TNP-OVA (2,4,6-trinitrophenyl coupled to ovalbumin) into the hind paw. Interferon-gamma (IFN-gamma) and interleukin 4 (IL-4) production was assessed in the popliteal lymph node (PLN) at Day 2 and Day 5 after injection by flow cytometry and ELISA. The number of IL-4-containing CD4(+) T cells increased between Day 2 and Day 5 in DEP- and CBP-exposed mice, in contrast to SIP-treated animals. IL-4 production by cultured PLN cells was also significantly increased for DEP- and CBP-treated animals. The secondary response was studied in different organs after an intranasal challenge with TNP-OVA (50 microgram), which was given 4 weeks after the initial subcutaneous injection. Five days after challenge the number of antibody-forming cells (AFCs) was assessed in peribronchial lymph nodes (PBLN), spleen, bone marrow, and PLN, and antibody levels were determined in weekly obtained blood samples. It appeared that all particles acted as adjuvant, but the different particles stimulated distinct types of immune responses to TNP-OVA. DEP-treated animals show high IgG1 and IgE levels in serum and high IgG1 and IgE-forming AFC numbers in PBLN, bone marrow, and spleen. CBP-treated animals show even higher IgG1 and IgE levels and AFC numbers, and in addition display IgG2a production. SIP-injected animals display predominantly IgG2a responses. It is concluded that DEP are able to skew the immune response toward the T helper 2 (Th2) side, whereas SIP stimulate a Th1 response and CBP have a mixed activity, stimulating both Th1 and Th2 responses in this model.

The use of reporter antigens in the popliteal lymph node assay to assess immunomodulation by chemicals.

Various drugs and other chemicals can induce T-cell-dependent B-cell activation which may lead to allergic or autoimmune-like diseases. Because the nature of the relevant (neo-) antigens is generally not known and probably depends on the chemical, we have explored the potential use of reporter antigens to determine T-cell-dependent B-cell activation by chemicals. TNP-Ficoll and TNP-OVA were used for this purpose because they are recognized by the same TNP-specific B cells, but these cells require distinct costimulation for specific antibody production. It was found that HgCl2, phenytoin, nitrofurantoin, and D-penicillamine stimulated IgG1 production to both antigens, incomplete Freund's adjuvant, silica, and dimethylsulfoxide to TNP-OVA only, and LPS and hydroxyl-amino procainamide to TNP-Ficoll alone. The diabetogene streptozotocin did not enhance IgG1 production, but may enhance a cellular response instead. Tolerogens and a T-cell antigen without intrinsic adjuvant activity did not influence the responses. The IgG1 production to TNP-Ficoll was local and transient, and did not always require T cells. In contrast, responses to TNP-OVA could be measured in serum, led to specific memory, and were strictly T-cell dependent. These results demonstrate that specific antibody production to reporter antigens indicates immunostimulatory effects of chemicals more sensitive than PLN cell count and provides important mechanistic information. Moreover, with TNP-OVA as reporter antigen the kinetics and regulation of chemically enhanced immune responses can be studied without the need to know the relevant neo-antigens for each individual compound.

Stress proteins (HSP) and chemical-induced autoimmunity.

Various environmental and iatrogenic chemicals have been implicated in the induction of autoimmune responses and biomarkers for identification of such chemicals are imperative. The present study was initiated to examine whether induction of stress protein (HSP) synthesis is a common effect of immunoactive chemicals. This would be interesting because HSP-induction could result in the presentation of HSP-derived T cell epitopes, and recognition of these epitopes by HSP-reactive T cells could facilitate the initiation of (auto)immune responses. Such a role for HSP would clarify early aspects of chemical induction of immune responses and could provide a valuable biomarker for the identification of potentially immunoactive chemicals. It was found that of eight immunoactive chemicals, only HgCl2, dinitrochlorobenzene, and dibutyltin dichloride induced synthesis of HSC73/HSP72 and HSP90 in murine splenocytes in vitro. The induction by HgCl2 was identical in splenocytes from mice susceptible or not for Hg-induced autoimmunity. Following footpad injection of HgCl2, but not diphenylhydantoin, a marginal induction of HSC73 and possibly HSP72 but not HSP90 was found to precede the chemical-induced lymphoproliferation in draining lymph nodes of BALB/c mice. Finally, using stimulation of the IgG1 response to TNP-ficoll as a model for non-antigen-linked, T cell-dependent B cell stimulation, it was found that stimulation of this response by chemicals is independent of HSP induction. From these results, we conclude that it is unlikely that HSP function as general initiating neoantigens in chemically induced autoimmune responses.

Local popliteal lymph node reactions to hexachlorobenzene and pentachlorobenzene: comparison with systemic effects.

The effects of the presumed autoimmunogenic chemical hexachlorobenzene (HCB), and the closely related non-autoimmunogenic pentachlorobenzene (PCB) in the local popliteal lymph node assay (PLNA) were investigated. To that end 1-5 mg of HCB, equimolar amounts of PCB or the vehicle only, were injected into the hind footpads of rats or mice, and the reaction in the draining lymph node was evaluated on days 7 and 21 after injection. PLN were isolated, weighed, and cell suspensions were prepared to determine PLN cell numbers, and antibody production of PLN cells with an ELISPOT assay or a line immunoassay. The extent of the lymphoproliferative effect was examined by detection of proliferating cells with the BrdU method, and by measurement of paracortex and follicle areas, by combined immunohistochemistry and morphometry of PLN cryosections. We demonstrate here that HCB elevated PLN weights and cell numbers of the rat PLN, by day 7 after injection, but no elevation of antibody production in the PLN. Moreover, HCB caused an enlargement of both the PLN paracortical and follicular areas, and an elevation of proliferating paracortical T cells. None of the HCB-induced effects were found on day 21. HCB caused the same effects in the mouse PLNA, but they tended to sustain at least until day 21. Hardly any of the HCB-induced changes were found when PCB was injected. Previously, we have shown that oral exposure of Wistar rats to HCB elevated the number of splenic T cells and B cells, but also the serum levels of (auto-)antibodies and the production of these antibodies in the spleen, which is thus only partly in accordance with the results of the local reaction to HCB described in this study. This seeming contradiction is discussed.

The effects of hypertension and diabetes mellitus on the vascular reactivity of resistance arteries.

We have studied the effects of both hypertension and streptozotocin-induced diabetes mellitus on alpha 1-adrenoceptor mediated vasoconstriction, endothelium-dependent and endothelium-independent vasodilation. The experiments were performed in perfused mesenteric vascular bed preparations taken from age-matched SHR, WKY, diabetic SHR and diabetic WKY. For the alpha 1-adrenoceptor agonist methoxamine, the mesenteric preparations from SHR and diabetic SHR yielded significantly (p < 0.05) stronger maximal responses than preparations taken from WKY and diabetic WKY, respectively. The diabetic state significantly (p < 0.05) decreased the responsiveness to methoxamine in arteries from SHR and WKY. Hypertension does not significantly change the concentration response-curves for (acetyl-beta) methacholine, histamine, adenosine diphosphate and sodium-nitroprusside. However, the sensitivity to endothelium-dependent vasodilation decreased in preparations from diabetic animals (< 0.05). It is concluded that mesenteric resistance arteries from SHR and diabetic SHR are more reactive to alpha 1-adrenoceptor stimulation, whereas diabetes reduces the responsiveness to methoxamine in WKY and SHR. Hypertension does not affect the endothelium-dependent relaxation in mesenteric arteries. However, diabetes decreases the sensitivity to endothelium-dependent relaxation without altering the sensitivity to sodium-nitroprusside. These findings are indicative of a diabetes-induced endothelial dysfunction in mesenteric resistance arteries. In preparations from diabetic hypertensive rats the reduced response to methoxamine and the endothelial dysfunction seem to run parallel.

Factors that define the susceptibility of endothelial cells to tumor necrosis factor and lipid A.

Factors defining the previously established differences in susceptibility of endothelial cells to the tumor-necrotizing agents, tumor necrosis factor (TNF) and lipid A, were investigated. Venous and arterial endothelial cells isolated from bovine and human umbilical cords showed large differences in proliferation rate and susceptibility to TNF and lipid A as measured by [3H]thymidine incorporation. The faster proliferating cells appeared more strongly inhibited by the agents. Also, using different isolates of human venous endothelial cells a similar correlation between proliferation rate and degree of inhibition was found. Growth stimulation of human venous cells with endothelial cell growth factor, but not the growth factor combined with heparin, increased the inhibitory action of the agents. Influence of the serum source was investigated by culturing human and bovine cells in the presence of human or bovine serum. Lipid A, but not TNF, was more inhibitory to cells of both species when cultured in bovine serum as compared to human serum. Supernatant of cultured tumor cells and serum from tumor-bearing mice increased the inhibitory effects of the agents as well. Data show that the action of the tumor-necrotizing agents on endothelial cells is defined by various factors, such as origin of the cells and culture conditions. In general, factors promoting cell proliferation tended to increase the susceptibility of the cells to the agents. The reported high vulnerability of tumors, wound tissue and placenta to induction of hemorrhage by these agents may be partially due to an enhanced sensitivity of the fast proliferating endothelium in these tissues.

Role of tumour necrosis factor in the tumour-necrotizing activity of agents with diverging toxicity.

We investigated the ability of various tumour-necrotizing agents with diverging toxicity to induce tumour necrosis factor (TNF) and cytostatic activity in Propionibacterium-acnes-primed Swiss and tumour-bearing BALB/c mice, and the capacity of anti-TNF antibodies to inhibit induction of tumour necrosis by the agents. Lipid A and especially its combination with muramyl dipeptide induced high TNF levels in Swiss mice, as measured in the serum. Lower levels were induced by detoxified lipid A and the nontoxic dsRNA, polyadenylic.polyuridylic acid, either alone or combined with muramyl dipeptide. The toxic agents also appeared the strongest inducers of mediators with cytostatic activity against cultured endothelial cells and MethA tumour cells. Anti-TNF antibodies partially reduced the cytostatic activity of the sera against MethA cells. Tumour-bearing BALB/c mice produced only low levels of TNF and cytostatic factors in response to all agents. Recombinant mouse TNF hardly reduced the DNA synthesis of MethA cells, unless normal mouse serum was added. Serum from P.-acnes-treated Swiss mice and tumour-bearing BALB/c mice, that were inhibitory on their own, failed to potentiate the action of TNF. Serum from Swiss mice treated with toxic, but not detoxified, lipid A caused extensive tumour necrosis upon injection into MethA-bearing BALB/c mice. This activity was completely abolished by pre-incubation of the serum with anti-TNF. The tumour-necrotizing activity of the agents could be partially reduced by prior injection of these antibodies. Results show that the capacity of the agents to induce TNF and cytostatic activity is not related to their antitumour potential. Although TNF is likely to be a crucial mediator of the tumour-necrotizing action of the toxic as well as the nontoxic agents, it is probably not the sole mediator. Data also indicate that induction of tumour necrosis does not require induction of high and, thus toxic, TNF levels in the serum.

Effect of tumour necrosis factor and lipid A on functional and structural vascular volume in solid murine tumours.

Effects of recombinant tumour necrosis factor (TNF) on functional and structural vascular volumes in solid murine Meth A tumours were investigated by injection of Hoechst 33342 and staining for the vascular basement membrane component laminin, respectively. Systemic injection of 3 x 10(4) U TNF caused an initial increase in functional volume in the tumour, but a strong decrease from 1 to 48 h after treatment. Early effects of intralesional treatment were more moderate. Systemic injection of 10(4) U TNF or 0.3 or 3 micrograms lipid A caused a fall in functional volume at 4 h, but a recovery was seen at 24 h. This recovery did not occur after treatment with a combination of 10(4) U TNF and 0.3 micrograms lipid A. Structural vascular volume was not markedly reduced until 24 h after treatment with the high doses of the separate agents and the combination. All effects appeared generally more prominent in the tumour centre than in the borders. Data suggest that TNF induces initially an active hyperaemia that rapidly converts to passive hyperaemia. A prolonged disturbance of tumour blood supply is probably necessary for therapeutic activity. Breakdown of laminin in the vascular basement membrane may be a cause of loss of vascular integrity.

Synergic action between tumor necrosis factor and endotoxins or poly(A.U) on cultured bovine endothelial cells.

In order to investigate whether direct effects on tumor vasculature may contribute to induction of necrosis of solid tumors in vivo, agents and combinations with an established different capacity to induce tumor necrosis were studied for their effects on endothelial cells in vitro. Tumor necrosis serum caused a marked inhibition of [3H]thymidine incorporation by bovine umbilical cord endothelial cells after 4 h coincubation. Endotoxin was less inhibitory, whereas detoxified endotoxin and recombinant human tumor necrosis factor (rTNF) were hardly active in concentrations that can be achieved in vivo. Combinations of rTNF and (detoxified) endotoxin caused synergic inhibition. By 24 h effects of the separate agents and synergic effects of the combinations were much stronger. The nontoxic dsRNA, poly(A.U), also had inhibitory activity, and acted synergistically with rTNF. Morphologically, a combination of endotoxin and rTNF but not the separate constituents induced marked cell detachment by 24 h, an indication of cell death. Whereas both endotoxin and rTNF inhibited DNA synthesis of human endothelial cells, the agents did not act synergistically on these cells. The ability of the agents and the combinations to affect endothelial cells in culture appeared to be well in line with their capacity to induce tumor necrosis. Data suggest that direct (synergic) effects on endothelium may contribute to the induction of vascular damage in tumors by (combinations of) the agents. The fact that endothelial cell death is only induced by the combinations and not by the separate agents in vivo, may be a cause of the greater therapeutic activity of the combinations in vivo. The synergy between rTNF and the other agents indicates that the agents act by different mechanisms.