The Pathophysiology of Collateral Circulation in Acute Ischemic Stroke

Cerebral collateral circulation is a network of blood vessels which stabilizes blood flow and maintains cerebral perfusion whenever the main arteries fail to provide an adequate blood supply, as happens in ischemic stroke. These arterial networks are able to divert blood flow to hypoperfused cerebral areas. The extent of the collateral circulation determines the volume of the salvageable tissue, the so-called "penumbra". Clinically, this is associated with greater efficacy of reperfusion therapies (thrombolysis and thrombectomy) in terms of better short- and long-term functional outcomes, lower incidence of hemorrhagic transformation and of malignant oedema, and smaller cerebral infarctions. Recent advancements in brain imaging techniques (CT and MRI) allow us to study these anastomotic networks in detail and increase the likelihood of making effective therapeutic choices. In this narrative review we will investigate the pathophysiology, the clinical aspects, and the possible diagnostic and therapeutic role of collateral circulation in acute ischemic stroke.

Lipid profiles and atrial fibrillation in ischemic stroke patients treated with thrombectomy: experience from a tertiary Italian stroke hospital

OBJECTIVES

To assess acute lipid profiles, atrial fibrillation and other cardiovascular risk factors in patients undergoing treatments by thrombectomy (EVT) with acute ischemic stroke (AIS).

METHODS

We performed a retrospective analysis of the lipid profile and vascular risk factor in 1639 consecutive patients with acute ischemic stroke between January 2016 and December 2021. To assess lipid profiles, laboratory tests, including total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), and triglycerides (TG), were obtained the day after admission. We also examined assessed the association between lipid profile, AF and EVT in multivariate logistic regression analysis.

RESULTS

Median age of patients was 74 years, 54.9% were males (95% CI 52.5-57.4%), and 26.8% (95% CI, 24.7-29.0%) had AF. EVT patients (n= 370; 22.57 %; 95% CI, 20.6-24.7) showed no difference in age (median 73 years [IQR; 63-80 ] versus 74 years [ QR; 63-82+ HbA1c levels (median 5.8 [IQR; 5.4-6.2] versus 5.9 [ IQR; 5.4-6.4+TG/HDL ratio (median 2.40 [IQR; 1.65-3.48#43; versus[IQR; 1.73-3.64)] diabetes (OR 0.82; 95% CI 0.61 to 1.08), hypertension (OR 0.87; 95% CI 0.68 to 1.12) and obesity (OR 1.06; 95% CI 0.78 to 1.42) compared to non-EVT patients. Conversely, EVT patients showed lower levels of TC (160 mg/dl[ IQR;139-187] versus 173 mg/dl [ IQR;148-202] P <0.001), LDL-C (105 mg/dl [ IQR; 80-133] versus 113 mg/dl [ IQR; 88-142] ; P <0.01), TG (98 mg/dl [ IQR; 76-126] versus 107 mg/dl [ IQR; 85-139] P <0.001), non-HDL-C (117 mg/dl[ IQR; 94-145] versus 127 mg/dl [ IQR; 103-154] P <0.001), HC (8.3[ mol/l [ IQR; 6-11] versus 10 µ mol/l[ IQR; 7.3-13.5] P <0.001) than non-EVT patients. Multivariate logistic regression analysis showed an independent association of EVT with TC (OR 0.99, 95% CI 0.98-0.99), AF (OR 1.79, 95% CI 1.34-2.38), age (OR 0.98, 95% CI 0.96-0.99), and NIHSS (OR 1.17, 95% CI 0.14-1.19).

CONCLUSION

Total cholesterol and all cholesterol-related measures were significantly lower in patients undergoing thrombectomy than in other stroke patients. Conversely, we found that AF was significantly high in patients with EVT, suggesting that hypercholesterolemia could be mainly linked to small-vessel occlusion stroke while large vessel occlusion (LVO) stroke could show different causes. AIS patients may have different pathogenesis and their understanding may improve enhance the discovery of specific and tailored preventive treatments.

Recurrent paraneoplastic cerebral hemorrhage in lung cancer: A case report

Cerebral hemorrhage management in a patient requiring anticoagulant therapy is a therapeutic challenge also due to the absence of guidelines that convincingly define the best therapeutic strategy. Although the occurrence of cerebral hemorrhage in a patient with anticoagulant therapy seems to make the bleeding etiology obvious, sometimes, it is better to reflect on other possible causes and set up an adequate diagnostic workup. Herein, we describe a case of a 73-year-old male patient with atrial fibrillation, mechanical heart valve, and pacemaker that experienced an ischemic minor stroke during steady anticoagulation therapy with recurrent intracerebral haemorrhages (ICHs).

An uncommon case of nonconvulsive status epilepticus successfully treated with enteral Brivaracetam

BACKGROUND AND AIM OF THE WORK

We present a case of a woman affected by nonconvulsive status epilepticus (NCSE) caused by cerebral hyperperfusion syndrome (CHS) after carotid endarterectomy (CEA) who was successfully treated with Brivaracetam (BRV) administered via nasogastric tube (NGT).

CASE PRESENTATION

An 82-years old woman was referred for increasing blood pressure, severe headache and two focal motor seizures on postoperative day four after right CEA. CT scan showed edema of the right hemisphere with a midline shift of 5 mm. The patient underwent daily Electroencephalography (EEG) monitoring which showed continuous epileptiform discharges over the right hemisphere, compatible with a diagnosis of status epilepticus. She was treated with standard antiepileptic drugs (Phenytoin, Lacosamide and Levetiracetam iv) without clinical response. A therapeutic trial with BRV 200mg administered via nasogastric tube (NGT) was tried which resulted in substantial clinical benefit.

CONCLUSIONS

The administration of new antiepileptic drugs (AEDs) such as BRV may result in significant clinical improvement in refractory cases of status epilepticus. The enteral administration of AEDs via NGT should always be considered for refractory cases of status epilepticus when standard iv treatment has failed or is not possible.

Ischemic Stroke in the Very Elderly: Experience from an Italian Stroke Unit Hub Over a Period of 8 Years in the Era of Thrombectomy

OBJECTIVE

The goal of this study is to understand how very elderly patients (VEP) after ischemic stroke are currently treated in a Stroke Unit (SU) Hub in Italy. We designed a retrospective monocentric study on patients admitted in the SU of "AO San Camillo Forlanini" over an 8-year period.

MATERIAL AND METHODS

Data were collected among patients with acute ischemic stroke admitted to SU between January 2012 and December 2019. Patients were divided into three sub-groups: Adults (18-65 years); Elderly (66-85 years); and VEP (>85 years). Vascular risk factors and clinical variables as predictors of short-term clinical outcome were compared among age groups.

RESULTS

A total of 1979 patients were enrolled, 254 were VEP (12.8%). The proportion of VEP showed no significant modifications during the 8-year period (11.9% in 2012-2015 and 13.7% in 2016-2019; p=0.93). The proportion of women, hypertension and atrial fibrillation was significantly higher in VEP compared to other age groups (p<0.001). The rate of VEP being treated with rt-PA increased from 2012-2015 to 2016-2019 (from 12.8% to 25.5%, p<0.001). Endovascular thrombectomy was rarely performed in VEP (1.5% of VEP). Rt-PA treatment was associated with favorable outcome for all three age groups (p<0.05).

CONCLUSIONS

We showed that VEP present different vascular risk factor profiles, clinical features, and prognostic elements for short-term stroke outcome. Future studies will reveal whether we will observe an increasing trend in the use of rt-PA and endovascular thrombectomy and whether it will result in improved functional outcome for VEP.

Unsuccessful Endovascular Treatment in a Patient With Stroke Onset of Takayasu Arteritis and Positive Clinical Outcome

Takayasu's arteritis (TA) is a chronic progressive vasculitis affecting large and medium-sized vessels, mainly in young subjects. It is most common in women with a higher prevalence in the Asian population. Stroke is a rare complication of TA, and these patients usually have a poor therapeutic response to revascularization treatments (thrombolysis and/or thrombectomy). We report a case of a male patient aged between 40 and 50 years admitted to our Emergency Department's Stroke Unit for sudden left hemiplegia, hypoesthesia, and dysarthria caused by right internal carotid artery (ICA), middle cerebral artery (MCA), and anterior cerebral artery (ACA) occlusion. He was treated with intravenous thrombolysis (r-tPA), endovascular carotid stenting, and thromboaspiration. We also revealed subclavian stenosis, vascular bruit, erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP) elevation; therefore, a diagnosis of TA was made. Double antiplatelet therapy (DAPT) was started. Despite the early post-procedural carotid stent occlusion, the patient was discharged with a full recovery (neurological index of stroke scale [NIHSS] = 0). Thefive5-year clinical follow-up showed no clinical neurological relapses, and no arterial restenosis was found by further carotid artery echo-Doppler. Takayasu arteritis is a rare cause of ischemic stroke in young adults; however, stroke may be the first manifestation of the disease. Guidelines concerning the role of revascularization treatment in this type of patients are unclear. In this regard, the clinical experience and the multidisciplinary approach applied in our case had a pivotal role. Such an approach would eventually advocate for standardized treatment in patients with stroke and TA. 

Effect of Cardioembolic Etiology on Intravenous Thrombolysis Efficacy for Acute Ischemic Stroke

Previous clinical studies suggest that intravenous (IV) recombinant tissue plasminogen activator (rt-PA) benefits stroke patients regardless of the underlying etiology. In this study, we assessed the possible differences in response to IV rt-PA between cardioembolic stroke and other stroke subtypes. A total of 303 consecutive stroke ischemic patients (from January 2005 to April 2014) admitted to our Stroke Unit and treated with IV rt-PA were retrospectively reviewed. All patients were classified in two groups: Cardioembolic (CE) and Non-Cardioembolic (NCE). We analyzed a total of 303 patients. Thirty patients died in the first hours after fibrinolysis and no statistically significant differences were found in two groups (14 CE vs 18 N-CE). We observed a significant differences in clinical outcome in terms of symptoms "improvement" (p< 0.01 .2) and symptoms" regression" (p<0.057 .2) even if this last result did not reach statistical significance in CE patients respect to N-CE patients. In conclusion, the intravenous fibrinolysis is more effective in CE group than in N-CE regarding symptoms "improvement" and the PFO-Stroke patients treated with fibrinolysis have better outcome than other patients and they have high rate of symptoms" regression". Moreover the main predictor of good outcomes were younger age and milder stroke severity on hospital admission.

Transient Ischemic Attack Fast-track and Long-Term Stroke Risk: Role of Diffusion-Weighted Magnetic Resonance Imaging

BACKGROUND

Acute ischemic lesions on diffusion-weighted magnetic resonance imaging (DWI-MRI) are reliable predictors of recurrent stroke at 90 days. However, to date, limited information on transient ischemic attack (TIA) patients with positive DWI lesions for stroke risk from 1 to 5 years is available. In this study, we evaluated the role of positive DWI lesions and vascular risk factors on stroke, cardiovascular death, and mortality at 90 days (T0), 1 year (T1), and 5 years (T2). Moreover, we also evaluated the association between stroke risk and the presence of DWI lesions.

METHODS

We performed an observational study on consecutive patients admitted to the emergency department of San Camillo-Forlanini Hospital, Rome, Italy, from January 2007 to November 2012. Over the study period, 4300 patients with TIA or ischemic stroke were examined by stroke specialists in an emergency room setting within 1 hour from admittance.

RESULTS

In 510 of 4300 patients (11.86%), a TIA was diagnosed, and 445 patients satisfy the study inclusion criteria. For all 445 patients, the mean ABCD2 score was 4.35 ± 1.30. Using DWI-MRI, we identified acute ischemic lesions in 185 patients (41.57%). We did not observe any correlation between duration of symptoms, ABCD2 score, and positive or negative DWI lesions. Positivity for DWI was not associated with the presence of diabetes mellitus, hypertension, smoking habit, or age; however, an association with weakness was observed. We documented a time-dependent increase in the absolute risk of stroke: T0: 1.35% (95% confidence interval [CI], .81-2.8); T1: 4.78% (95% CI, 2.88-7.47); T2: 9.02% (95% CI, 4.66-5.70). We did not record any difference in stroke risk in patients with positive DWI lesions: T0: hazard ratio [HR], 1.43; 95% CI, .35-5.88; log-rank P = .60; T1: HR, 1.04; 95%CI, .42-2.61; log-rank P = .91; T2: HR, .83; 95% CI, .25-2.67; log-rank P = .86.

CONCLUSIONS

This long-term follow-up study in TIA patients documents that both positive and negative DWI patients treated with fast-track had similar long-term risks of stroke.

Pulmonary arteriovenous malformation as a cause of embolic stroke: case report and review of the literature

BACKGROUND

Pulmonary arteriovenous malformation (PAVM) is an abnormal communication between pulmonary arteries and veins responsible for right-to-left shunting that could induce the development of embolic stroke.

SUMMARY

We describe an 82-year-old woman without history of respiratory or neurological diseases, who presented at our observation unit with acute onset of cerebral ischemia. Clinical, laboratory and radiological findings diagnosed a PAVM.

KEY MESSAGES

Usually, endovascular procedures based on embolization or, alternatively, surgery represent the recommended treatment. However, both hormonal therapy and thrombolytic therapy can be used. In our patient, treatment with warfarin induced a remission of symptoms. This strategy should be tested in larger studies.

Endothelial dysfunction and oxidative stress in type 1 and type 2 diabetic patients without clinical macrovascular complications

AIMS

To evaluate the relationship between oxidative stress and endothelial dysfunction (ED) in diabetic patients without clinical macrovascular complications.

METHODS

In 27 type 1, 56 type 2 diabetic patients and 35 healthy controls the redox state (GSH, GSSG; enzymatic method), endothelin-1 (ET-1; ELISA) and von Willebrand factor (vWF; ELISA) plasma levels, urinary vascular endothelial growth factor (VEGF; ELISA) were measured.

RESULTS

Decreased GSH levels (p<0.05, type 1 and type 2), GSH/GSSG ratio (p<0.05 type 1, p<0.001 type 2) and elevated vWF levels (p<0.001, type 1 and type 2) were observed in diabetic patients in comparison with controls. A negative correlation between GSH and vWF (p<0.02 and p<0.001, in type 1 and type 2, respectively) and GSH and BMI (p<0.02 in type 1 and type 2) was observed. ET-1 was positively correlated to age (p<0.05) and diabetes duration (p<0.03) in type 1, while vWF was correlated to systolic blood pressure (p<0.05) in type 2 diabetic patients. Urinary VEGF was higher in type 2 (p<0.05) in comparison with type 1 diabetic patients and was correlated to glycemia (p<0.05) and systolic blood pressure (p<0.05).

CONCLUSIONS

These data might indicate that markers of oxidative stress and ED are altered in diabetic patients without clinical macrovascular complications.

Insulin decreases intracellular oxidative stress in patients with type 2 diabetes mellitus

Patients affected by diabetes mellitus have oxidative stress with an impaired glutathione (GSH) redox state. The objective of this study was to determine the influence of insulin on oxidative stress, defined as a reduced intracellular GSH/GSH disulfide (GSSG) ratio and lipid peroxidation by plasma thiobarbituric acid reactive substances (TBARSs) in patients with type 2 diabetes. Two experimental interventions were used: (1) measurement of GSH/GSSG ratio after insulin incubation in erythrocytes from 10 type 2 diabetic patients, and (2) measurement of intraerythrocytic GSH/GSSG ratio and plasma TBARS in 14 type 2 diabetic patients during an in vivo hyperinsulinemic condition obtained from a euglycemic hyperinsulinemic clamp study. We confirmed that our patients underwent oxidative stress as shown by the significant difference in intracellular GSH/GSSG ratio in diabetic patients as compared to controls (13.56+/-3.84 vs 27.89+/-8.37, P<.0001). We found a significant elevation in the GSH/GSSG ratio after 2 hours of incubation with insulin in erythrocytes from diabetic patients (11.56+/-1.98 to 15.61+/-2.62, P<.001). During the clamp studies, GSH/GSSG ratio had already increased after 60 minutes and even more after 120 minutes (baseline, 15.04+/-4.19; at 60 minutes, 19.74+/-6.33; at 120 minutes, 25.33+/-11.15; P<.0001). On the contrary, no significant changes were observed in plasma TBARS (3.59+/-0.77 to 3.56+/-0.83, NS). We conclude that insulin in patients with type 2 diabetes mellitus can reduce intracellular oxidative stress through increased GSH/GSSG ratio.

Impairment of cell and plasma redox state in subjects professionally exposed to chromium

BACKGROUND

Chromium (Cr) is widely used in chemical, tannery, building, and metal industries. More recently, it has been demonstrated that Cr induces oxidative stress in mouse brain. Nevertheless very few data exist on in vivo oxidative damage in humans exposed to Cr.

METHODS

Changes in antioxidant parameters both in plasma (acid ascorbic redox state and total antioxidant capacity) and in red blood cells (glutathione (GSH) redox state) of 40 subjects (age 37.65 +/- 7.46; M/F 20/20) professionally exposed to Cr who were recruited from metal, chemistry, and building industries were evaluated. We also evaluated the levels of lipoperoxidation (thiobarbituric acid-reactive material, TBA-RM) and thiol levels in plasma to assess the extent of oxidative stress state. To evaluate Cr exposure rate, we measured urinary-chromium (U-Cr) by an electrothermic atomization-atomic absorption spectrometry (ETA-AAS) method.

RESULTS

In this study, we found that Cr exposure induced a decrease both in GSH (P < 0.0005) and GSH/oxidized glutathione (GSSG) ratio (P < 0.0001) in red blood cells from workers with respect to control subjects. Furthermore, we also demonstrated a significant decrease of plasma acid ascorbic levels (45.7 +/- 14.9 vs. 53.5 +/- 16.5 micromol/L; P < 0.05) and in total plasma antioxidant capacity (1,126.3 +/- 212.2 vs. 1,266.9 +/- 207.8 micromol/L; P < 0.05) in subjects exposed to Cr. No difference was found with regard to TBA-RM and thiol levels.

CONCLUSIONS

This study demonstrated that in humans, an oxidative stress occurs for Cr exposures as low as those considered safe. This oxidative stress appears to be able to affect intracellular and plasmatic antioxidant defense.

Angiotensin II inhibits endothelial cell motility through an AT1-dependent oxidant-sensitive decrement of nitric oxide availability

OBJECTIVE

The migratory capability of vascular endothelial cells plays a pivotal role in the maintenance of vessel wall integrity and is stimulated by nitric oxide (NO). Angiotensin II increases NAD(P)H oxidase activity in endothelial cells, thereby promoting reactive oxygen species (ROS) generation. Because ROS can both reduce NO synthase activity and increase NO breakdown, thus impairing NO availability in endothelial cells, we evaluated the effect of angiotensin II on human vascular endothelial cell (HUVEC) motility.

METHODS AND RESULTS

Angiotensin II dose- and time-dependently reduced HUVEC migration. Besides inhibiting HUVEC motility, angiotensin II altered intracellular glutathione redox status. The generation of ROS by cultured HUVECs was significantly increased by angiotensin II. Furthermore, angiotensin II reduced NO metabolite concentrations in culture media. The angiotensin II type 1 receptor antagonist candesartan cilexetil attenuated the inhibitory action exerted by angiotensin II on HUVEC motility, reversed the angiotensin II-induced increase in intracellular oxidative stress, and restored NO availability. Similar effects were exerted by the flavonoid inhibitor diphenylene iodinium and the antioxidant agent N-acetyl-L-cysteine.

CONCLUSIONS

All together, our data demonstrate that angiotensin II inhibits HUVEC motility by reducing NO availability. Such reduction is due to an angiotensin II type 1 receptor-dependent increment in intracellular ROS generation.

L-arginine infusion decreases plasma total homocysteine concentrations through increased nitric oxide production and decreased oxidative status in Type II diabetic patients

AIMS/HYPOTHESIS

Hyperhomocysteinaemia increases cardiovascular risk in Type II (non-insulin-dependent) diabetes mellitus by augmenting oxidative stress and reducing nitric oxide availability. In vitro, nitric oxide decreases homocysteine by its conversion to the vasodilative and antioxidant compound S-nitrosohomocysteine. We investigated whether or not changes in nitric oxide availability decrease homocysteine concentrations in vivo.

METHODS

The study group consisted of 20 normotensive, normolipidaemic, non-atherosclerotic Type II diabetic patients in good metabolic control (16 men, 51.2+/-1.4 years) and 15 healthy subjects (12 men, 48.1+/-1.5 years). Circulating concentrations of homocysteine, nitrite+nitrate and sulphydryl groups, a marker of oxidative stress, were assessed at baseline and then 5', 10', 30' and 60' after the intravenous infusion of either L-arginine (3 g in 10 ml saline), the nitric oxide precursor, or vehicle according to a double-blind cross-over randomized protocol.

RESULTS

At baseline diabetic patients showed lower plasma sulphydryl group concentrations (491.8+/-16.9 vs 551.3+/-21.0 micro mol/l, p<0.04) and nitrite+nitrate (21.4+/-0.8 vs 29.5+/-0.9 micro mol/l, p<0.0001) and higher total homocysteine concentrations (11.1+/-0.5 vs 8.3+/-0.6 micro mol/l, p<0.002) than the control subjects. After L-arginine infusion, blood pressure levels and total homocysteine concentrations ( p< or =0.05) decreased (peak at 5' and 30', respectively) whereas nitric oxide and sulphydryl group concentrations ( p< or =0.003) increased (peak at 10' and 30', respectively) in the patients and control subjects.

CONCLUSION/INTERPRETATION

Acute L-arginine infusion in both Type II diabetic patients and healthy subjects decreases plasma total homocysteine concentrations, counteract oxidative stress and increases the availability of nitric oxide.

Angiotensin II stimulates intercellular adhesion molecule-1 (ICAM-1) expression by human vascular endothelial cells and increases soluble ICAM-1 release in vivo

BACKGROUND

We evaluated whether angiotensin II (Ang II) influenced intercellular adhesion molecule (ICAM)-1 expression by human vascular endothelial cells derived from umbilical cord veins (HUVECs) and plasma soluble ICAM-1 levels in vivo.

METHODS AND RESULTS

Cultured HUVECs were incubated with Ang II (from 10(-9) to 10(-6) mol/L) with or without candesartan and PD12319 (inhibitors of Ang II AT(1) and AT(2) receptors, respectively) for various times up to 4 hours. Total RNA was then extracted from HUVECs, and Northern blots were probed with a 1.9-kb ICAM-1 cDNA fragment. HUVEC supernatants were used to assess soluble ICAM-1 release by ELISA. Northern blot analysis detected a strong increase of ICAM-1 mRNA after 2-hour incubation with Ang II. The response was inhibited by candesartan. Soluble ICAM-1 release by HUVECs also increased (P<0. 002) after 2-hour Ang II stimulation. In vivo, Ang II (at an initial rate of 1.0 ng. kg(-1). min(-1), to be increased each 30 minutes by 2.0 ng. kg(-1). min(-1) to the final rate of 7.0 ng. kg(-1). min(-1)) was infused in 8 normotensive and 12 essential hypertensive individuals. In the latter, Ang II was reinfused after 4 weeks on either placebo (n=3), losartan (50 mg UID, n=5), or atenolol (50 mg UID, n=4) treatment. Plasma soluble ICAM-1 levels increased after Ang II infusion in hypertensives and normotensives (P<0.0001 after 90 minutes). Losartan reduced baseline soluble ICAM-1 levels (P<0.05) and Ang II-related ICAM-1 increments.

CONCLUSIONS

Ang II upregulates ICAM-1 expression by HUVECs and stimulates in vitro and in vivo soluble ICAM-1 release. AT(1) receptor blockade inhibits such endothelial effects of Ang II.

Effects of insulin on in vitro vascular cell adhesion molecule-1 expression and in vivo soluble VCAM-1 release

AIMS/HYPOTHESIS

To evaluate the effects of insulin on vascular cell adhesion molecule-1 expression by cultured human vascular endothelial cells and soluble vascular cell adhesion molecule-1 release in vivo.

METHODS

Human vascular endothelial cells derived from umbilical cord veins were incubated with either insulin (from 10(-6) to 10(-9) mol/l) or tumour necrosis factor-alpha (5 ng/ml) for 6 to 24 h. Plasma soluble vascular cell adhesion molecule-1 concentrations were evaluated in 12 non-insulin-dependent diabetic patients (8 men, 4 women, mean age 47.1 +/- 7.7 years) and 12 healthy volunteers matched for age, sex and weight (7 men, 5 women, mean age 42.2 +/- 7.2 years) before and after a 2-h euglycaemic hyperinsulinaemic clamp.

RESULTS

Transcriptional activities of nuclear factor-kappaB luciferase and vascular adhesion molecule-1 luciferase statistically significantly increased after incubation with tumour necrosis factor-alpha. By contrast, a slight increment of nuclear factor-kappaB luciferase (mean: 1.8 +/- 0.3 fold) but not of vascular cell adhesion molecule-1 luciferase transcriptional activities were detected in cells stimulated with insulin. Soluble vascular cell adhesion molecule-1 concentrations in cell supernatants increased after tumour necrosis factor-alpha but not insulin stimulation. In vivo, baseline plasma soluble vascular cell adhesion molecule-1 concentrations were higher (p = 0.03) in non-insulin-dependent patients (708.7 +/- 97.4 microg/l) than controls (632.1 +/- 65.2 microg/l) but were not related to fasting insulin concentrations and did not change during insulin infusion.

CONCLUSION/INTERPRETATION

The increased concentrations of circulating soluble vascular cell adhesion molecule-1 indicates that the vascular endothelium is activated in non-insulin dependent diabetic patients. Our in vitro and in vivo findings show that vascular cell adhesion molecule-1 activation cannot be due to hyperinsulinaemia. [Diabetologia (1999) 42: 1235-1239]

Reduction of oxidative stress by oral N-acetyl-L-cysteine treatment decreases plasma soluble vascular cell adhesion molecule-1 concentrations in non-obese, non-dyslipidaemic, normotensive, patients with non-insulin-dependent diabetes

To assess in vivo effects of antioxidants on vascular cell adhesion molecule (VCAM)-1 expression, circulating soluble VCAM-1 and intraerythrocytic reduced glutathione (GSH) and GSH disulphide (GSSG) concentrations were evaluated in non-insulin-dependent diabetic patients without complications (9 men, 6 women, 48 +/- 6 years old) before and after 1 month of either oral N-acetyl-L-cysteine (1.200 mg/day) or placebo treatments, given in randomized, cross-over, double-blind fashion. Ten healthy subjects (7 men, 3 women, 52 +/- 4 years old) served as control subjects. Baseline plasma VCAM-1 concentrations were higher (p = 0.007) in non-insulin-dependent diabetic patients (707.9 +/- 52.5 ng/ml) than in control subjects (627.3 +/- 84.6 ng/ml). Intraerythrocytic GSSG content was higher (non-insulin dependent diabetic patients: 0.618 +/- 0.185 micromol/g Hb; control subjects: 0.352 +/- 0.04 micromol/g Hb, p = 0.0002), whereas intraerythrocytic GSH concentrations were lower (p = 0.001) in non-insulin dependent diabetic patients (6.0 +/- 0.7 micromol/g Hb) than in control subjects (7.1 +/- 0.5 micromol/g Hb). The mean GSH:GSSG ratio was also lower (p = 0.0001) in the first (10.9 +/- 4.5) than in the second group (20.2 +/- 1.4). Circulating VCAM-1 and intraerythrocytic GSH concentrations were negatively correlated in non-insulin diabetic patients (r = 0.605, p = 0.01). Treatment with N-acetyl-L-cysteine decreased plasma VCAM-1 (p = 0.01) and intraerythrocytic GSSG (p = 0.006) but increased GSH concentrations (p = 0.04) and the GSH:GSSG ratio (p = 0.004) in non-insulin dependent diabetic patients. Our data indicate that the vascular endothelium is activated in non-insulin dependent diabetes. Antioxidant treatment counterbalanced such endothelial activation. Thus, antioxidant agents might protect against oxidant-related upregulation of endothelial adhesion molecules and slow down the progression of vascular damage in non-insulin dependent diabetes.

Influence of reduced glutathione infusion on glucose metabolism in patients with non-insulin-dependent diabetes mellitus

To evaluate the relationship between oxidative stress and glucose metabolism, insulin sensitivity and intraerythrocytic reduced glutathione (GSH)/oxidized glutathione (GSSG) ratio were measured in 10 non-insulin-dependent diabetes mellitus (NIDDM) patients and 10 healthy subjects before and after the intravenous administration of GSH. In particular, after baseline insulin sensitivity was assessed by a 2-hour euglycemic hyperinsulinemic clamp, either glutathione (1.35 g x m2 x min(-1)) or placebo (saline) were infused over a period of 1 hour. The same protocol was repeated at a 1-week interval, in cross-over, according to a randomized, single-blind design. In healthy subjects, baseline intraerythrocytic GSH/GSSG ratio (P < .0005) and total glucose uptake (P < .005) were significantly higher than in NIDDM patients. In the same subjects, GSH infusion significantly increased total glucose uptake (from 37.1 +/- 6.7 micromol kg(-1) x min(-1) to 39.5 +/- 7.7 micromol x kg(-1) x min(-1), P < .05), whereas saline infusion was completely ineffective. In addition, the mean intraerythrocytic GSH/GSSG ratio significantly increased after GSH infusion (from 21.0 +/- 0.9 to 24.7 +/- 1.3, P < .05). Similar findings were found in diabetic patients, in whom GSH infusion significantly increased both total glucose uptake (from 25.3 +/- 9.0 micromol x kg(-1) x min(-1) to 31.4 +/- 10.0 micromol x kg(-1) x min(-1), P < .001) and intraerythrocytic GSH/GSSG ratio (from 14.8 +/- 4.1 to 21.7 +/- 6.7, P < .01). Pooling diabetic patients and controls, significant correlations were found between intraerythrocytic GSH/GSSG ratio and total glucose uptake (r = .425, P < .05), as well as between increments of the same variables after GSH infusion (r = .518, P < .05). In conclusion, our data support the hypothesis that abnormal intracellular GSH redox status plays an important role in reducing insulin sensitivity in NIDDM patients. Accordingly, intravenous GSH infusion significantly increased both intraerythrocytic GSH/GSSG ratio and total glucose uptake in the same patients.

Role of plasma and urinary endothelin-1 in early diabetic and hypertensive nephropathy

To evaluate the role of circulating and renal endothelin-1 (ET-1) in early diabetic nephropathy, plasma ET-1 levels and urinary ET-1 excretion were evaluated in lean, normotensive patients affected by non-insulin-dependent diabetes (NIDDM) either with (n = 9, NIDDM+) or without microalbuminuria (n = 18, NIDDM-); in never-treated, lean, essential hypertensive patients with (n = 12, EH+) or without microalbuminuria (n = 10, EH-); and in healthy volunteers (n = 12). Results showed higher plasma ET-1 levels in NIDDM+ (1.97 +/- 0.58 pg/mL) than in NIDDM- (1.59 +/- 0.14 pg/mL, P = .013), EH+ (1.40 +/- 0.21 pg/mL, P = .005), EH- (0.91 +/- 0.19 pg/mL, P < .0001), and controls (0.60 +/- 0.10 pg/mL, P < .0001). The circulating ET-1 concentration was also higher in EH+ than EH- and controls (P < .0001). Urinary ET-1 excretion did not differ (P = .387, NS) between NIDDM+ (48.5 +/- 20.1 pg/min) and NIDDM- (40.9 +/- 21.6 pg/min), but was significantly reduced (P < .0001) in both groups compared with controls (70.0 +/- 15.5 pg/min). Similar findings were observed in hypertensive subgroups. No correlations were found between urinary ET-1 and other variables, including plasma ET-1 levels, in all groups. In conclusion, NIDDM+ is accompanied by a significant increase in plasma ET-1 levels. A significant elevation of circulating ET-1 concentration was evident also in NIDDM-, suggesting that early abnormalities of ET-1 production might precede the microalbuminuric phase of diabetes-related renal damage.

Polyol pathway activation and glutathione redox status in non-insulin-dependent diabetic patients

The current study aimed to evaluate whether nicotinamide adenine dinucleotide phosphate (NADPH) alteration in erythrocytes from patients with non-insulin-dependent diabetes mellitus (NIDDM) is responsible for the impaired glutathione (GSH) redox status, and to assess if short-term inhibition of the polyol pathway normalizes NADPH levels and GSH redox status via an amelioration of the NADPH/total NADP (tNADP) ratio. For this purpose, erythrocyte NADPH and GSH levels were measured in 18 NIDDM patients at baseline and then after 1 week of random double-blind assignment to treatment with either tolrestat (an aldose reductase inhibitor, 200 mg daily) (n = 12) or placebo (n = 6). A group of 16 healthy volunteers served as the control. In the basal condition, mean GSH (P < .0001) and NADPH (P < .0001) levels and NADPH/tNADP (P < .0001) and GSH/ glutathione disulfide (GSSG) (P < .005) ratios were lower in NIDDM patients than in control subjects. Tolrestat treatment increased GSH levels (P < .05 v placebo and baseline) and the NADPH/tNADP ratio (P < .05 v placebo and baseline). Interestingly, tolrestat-induced changes in GSH and NADPH levels and in GSH/GSSG and NADPH/tNADP ratios were significant only in patients who showed a decreased NADPH/tNADP ratio at baseline (n = 8). In these latter patients, we also found a direct correlation between percentage increments in GSH levels and NADPH/tNADP ratios after tolrestat treatment (r = .71, P < .05). In conclusion, our findings support the hypothesis that polyol pathway activation decreases NADPH and GSH levels. Accordingly, short-term inhibition of this enzymatic route increased both the GSH level and the NADPH/tNADP ratio. These changes were observable only in the subgroup of patients with an abnormal NADPH/tNADP ratio at baseline. Polyol pathway inhibition could be useful for decreasing oxidative stress in NIDDM.

[Evoked motor and somatosensory potentials in diabetic neuropathy]

The present study was aimed at evaluating the information obtained from evoked motor and sensitive potentials in a population of non-insulin-dependent diabetics compared to information yielded by electroneurographic study. Besides, we wanted to check any possible correlation between metabolic control and changes of evoked potentials. Electroneurographic study of 20 patients revealed signs of peripheral nervous impairment in 11 of these while results were normal in the remaining 9. Analysis of findings resulting from testing of evoked potentials showed a statistically significant increase of these parameters both in the group of patients with neuropathy and in the controls. Since these methods explore longer stretches of the nervous pathways, they are apt to identify lesions located in areas not accessible to common diagnostic methods. Our data did not show a correlation between metabolic control, as assessed by fructosamine assay, and latency of evoked motor and sensitive potentials, thus indicating that other factors, such as environmental and genetic ones, are apt to influence the onset of diabetic neuropathy.

[Evaluation of the efficacy of metformin-glibenclamide treatment in overweight non-insulin dependent diabetics]

The authors evaluated the efficacy of treatment with the metformin-glibenclamide combination in 30 non-insulin dependent overweight diabetic patients in poor metabolic control during sulfonylurea treatment. After three months' therapy, a significant reduction of glycaemia, insulinaemia and fructosamine were found. Therefore, the addition of biguanides in those patients, was able to reduce blood glucose levels and to improve insulin resistance. In addition the metformin glibenclamide combination never produced relevant side effects of lactic acidosis, which is the most dangerous event during biguanide treatment.