Efficacy and safety of canagliflozin when used in conjunction with incretin-mimetic therapy in patients with type 2 diabetes.

AIMS: To assess the efficacy and safety of canagliflozin, a sodium glucose co-transporter 2 (SGLT2) inhibitor, in patients with type 2 diabetes enrolled in the CANagliflozin cardioVascular Assessment Study (CANVAS) who were on an incretin mimetic [dipeptidyl peptidase-4 (DPP-4) inhibitor or glucagon-like peptide-1 (GLP-1) receptor agonist]. METHODS: CANVAS is a double-blind, placebo-controlled study that randomized participants to canagliflozin 100 or 300 mg or placebo added to routine therapy. The present post hoc analysis assessed the efficacy and safety of canagliflozin 100 and 300 mg compared with placebo in subsets of patients from CANVAS who were taking background DPP-4 inhibitors or GLP-1 receptor agonists with or without other antihyperglycaemic agents at week 18. RESULTS: Of the 4330 patients in CANVAS, 316 were taking DPP-4 inhibitors and 95 were taking GLP-1 receptor agonists. At 18 weeks, canagliflozin 100 and 300 mg provided larger placebo-subtracted reductions in glycated haemoglobin (HbA1c) in patients taking DPP-4 inhibitors [-0.56% (95% confidence interval [CI]: -0.77, -0.35), and -0.75% (95% CI: -0.95, -0.54), respectively] and GLP-1 receptor agonists [-1.00% (95% CI: -1.35, -0.65), and -1.06% (95% CI: -1.43, -0.69), respectively]. Body weight and blood pressure (BP) reductions were seen with canagliflozin versus placebo in both subsets. Higher incidences of genital mycotic infections and osmotic diuresis-related adverse events (AEs) were seen with canagliflozin compared with placebo. The incidence of hypoglycaemia was numerically higher with canagliflozin versus placebo; nearly all events occurred in patients on background insulin or insulin secretagogues. CONCLUSIONS: In patients on background incretin mimetics, canagliflozin improved HbA1c, body weight and BP, with an increased incidence of AEs related to SGLT2 inhibition.

Effect of canagliflozin on serum uric acid in patients with type 2 diabetes mellitus.

Hyperuricaemia is associated with an increased risk of gout, kidney stones and cardiovascular disease. The present post hoc analysis of pooled data from four placebo-controlled phase III studies assessed the effect of canagliflozin, a sodium-glucose co-transporter 2 inhibitor, on serum uric acid levels in patients with type 2 diabetes mellitus (T2DM) and in a subset of patients with hyperuricaemia [defined as baseline serum uric acid ≥475 µmol/l (∼8 mg/dl)]. At week 26, canagliflozin 100 and 300 mg were associated with a ∼13% reduction in serum uric acid compared with placebo. In the subset of patients with hyperuricaemia, placebo-subtracted percent reductions in serum uric acid were similar to those in the overall cohort. More patients in the hyperuricaemic group achieved a serum uric acid level of <360 µmol/l (∼6 mg/dl) with both canagliflozin 100 mg (23.5%) and 300 mg (32.4%) compared with placebo (3.1%). Incidences of gout and kidney stones were low and similar across groups. In conclusion, canagliflozin treatment decreased serum uric acid in patients with T2DM, including those with baseline hyperuricaemia.

Canagliflozin in Asian patients with type 2 diabetes on metformin alone or metformin in combination with sulphonylurea.

AIMS: To evaluate the efficacy and safety of canagliflozin, a sodium glucose co-transporter 2 inhibitor, in Asian patients with type 2 diabetes mellitus (T2DM) inadequately controlled by metformin or metformin in combination with sulphonylurea. METHODS: In this 18-week, randomized, double-blind, placebo-controlled phase III study, patients (N = 676) received canagliflozin 100 or 300 mg or placebo once daily. The primary efficacy endpoint was change in glycated haemoglobin (HbA1c) level from baseline at week 18. Additional endpoints included change in fasting plasma glucose (FPG) and percent change in body weight. Adverse events (AEs) were recorded throughout the study. Efficacy and safety were assessed in the overall population and in two strata based on background therapy. RESULTS: At week 18, canagliflozin 100 and 300 mg provided significant reductions from baseline in HbA1c compared with placebo (-0.97, -1.06 and -0.47%, respectively; p < 0.001). Relative to placebo, canagliflozin 100 and 300 mg also significantly reduced FPG (-1.0 and -1.4 mmol/l) and body weight [-2.2% (-1.5 kg) and -2.3% (-1.6 kg)]. Both canagliflozin doses lowered systolic blood pressure (BP) compared with placebo. The overall incidence of AEs was 38.6, 43.2 and 42.0% with canagliflozin 100 and 300 mg and placebo, respectively. The incidence of genital mycotic infections and urinary tract infections was low and similar across groups. Efficacy and safety findings in the two strata were generally consistent with the overall population. CONCLUSIONS: Canagliflozin provided glycaemic improvements and reductions in body weight and systolic BP, and was generally well tolerated in Asian patients with T2DM on metformin or metformin in combination with sulphonylurea.

Long-term efficacy and safety of canagliflozin over 104 weeks in patients aged 55-80 years with type 2 diabetes.

AIMS: The long-term efficacy and safety of canagliflozin, a sodium glucose co-transporter 2 inhibitor, was evaluated over 104 weeks in patients aged 55-80 years with type 2 diabetes mellitus (T2DM) inadequately controlled on a stable antihyperglycaemic agent regimen. METHODS: In this randomized, double-blind, phase III study, patients received canagliflozin 100 or 300 mg or placebo once daily during a 26-week core period (N = 714) and a 78-week extension period (n = 624). Efficacy endpoints at week 104 included change from baseline in glycated haemoglobin (HbA1c), fasting plasma glucose (FPG) and systolic blood pressure, and percent change from baseline in body weight and fasting plasma lipids. Safety was assessed by adverse event (AE) reports. RESULTS: At week 104, canagliflozin 100 and 300 mg were associated with reductions in HbA1c versus placebo (-0.32 and -0.43% vs 0.17%, respectively; overall mean baseline, 7.7%) and more patients achieved HbA1c <7.0% with canagliflozin 100 and 300 mg than with placebo (35.8 and 41.9% vs 20.3%, respectively). Reductions in FPG, body weight and systolic blood pressure, and increases in high-density lipoprotein cholesterol (HDL-C) and low-density lipoprotein cholesterol (LDL-C) were seen with canagliflozin compared with placebo. The overall incidence rates of AEs over 104 weeks were 88.0, 89.8 and 86.1% with canagliflozin 100 and 300 mg and placebo, respectively; serious AE rates were low across treatment groups. The incidence rates of urinary tract infections, genital mycotic infections and osmotic diuresis- and volume depletion-related AEs were higher with canagliflozin than with placebo. CONCLUSION: Canagliflozin improved glycaemic control, reduced body weight and systolic blood pressure, and was generally well tolerated in patients aged 55-80 years with T2DM over 104 weeks.

Efficacy and safety of canagliflozin over 52 weeks in patients with type 2 diabetes on background metformin and pioglitazone.

AIM: The efficacy and safety of canagliflozin, a sodium glucose co-transporter 2 inhibitor, was evaluated in patients with type 2 diabetes mellitus (T2DM) inadequately controlled with metformin and pioglitazone. METHODS: In this randomized, double-blind, phase 3 study, patients (N = 342) received canagliflozin 100 or 300 mg during a 26-week, placebo-controlled, core period and a 26-week, active-controlled extension in which placebo-treated patients were switched to sitagliptin 100 mg. Efficacy comparisons for canagliflozin versus placebo at week 26 are reported, with no comparisons versus sitagliptin at week 52 (sitagliptin used to maintain double-blind and control for safety). Safety data are reported for canagliflozin and placebo/sitagliptin. RESULTS: Canagliflozin 100 and 300 mg significantly lowered haemoglobin A1c (HbA1c) compared with placebo at week 26 (-0.89%, -1.03% and -0.26%; p < 0.001); reductions with canagliflozin 100 and 300 mg were maintained at week 52 (-0.92% and -1.03%). Relative to placebo, both canagliflozin doses significantly reduced body weight (-2.5 and -3.5 kg), fasting plasma glucose and systolic blood pressure (BP) at week 26 (p < 0.05 for all), with reductions maintained at week 52. Overall adverse event (AE) incidence over 52 weeks was 69.9, 76.3 and 76.5% with canagliflozin 100 and 300 mg and placebo/sitagliptin; AE-related discontinuation and serious AE rates were low. Incidences of genital mycotic infections and AEs related to osmotic diuresis and volume depletion were higher with canagliflozin than placebo/sitagliptin. CONCLUSION: Canagliflozin improved glycaemic control, reduced body weight and systolic BP, and was generally well tolerated in patients with T2DM on metformin and pioglitazone over 52 weeks.

Efficacy and safety of canagliflozin over 52 weeks in patients with type 2 diabetes mellitus and chronic kidney disease.

AIM: This study evaluated the efficacy and safety of canagliflozin, a sodium glucose co-transporter 2 inhibitor, in patients with type 2 diabetes mellitus (T2DM) and within a subset of Stage 3 chronic kidney disease (CKD; estimated glomerular filtration rate [eGFR] ≥ 30 and <50 ml/min/1.73 m(2)). METHODS: In this 52-week, randomized, double-blind, placebo-controlled study, patients (N = 269; mean eGFR, 39.4 ml/min/1.73 m(2)) received canagliflozin 100 or 300 mg and placebo once daily. Efficacy endpoints included changes in glycated haemoglobin (HbA1c), fasting plasma glucose (FPG), body weight and systolic blood pressure (BP); adverse events (AEs) were also recorded. RESULTS: At week 52, canagliflozin 100 and 300 mg reduced HbA1c compared with placebo (-0.19, -0.33 and 0.07%, respectively); placebo-subtracted differences (95% confidence interval) were -0.27% (-0.53, 0.001) and -0.41% (-0.68, -0.14). Canagliflozin also lowered FPG, body weight and BP versus placebo. Overall AE incidence was 85.6, 80.9, and 86.7% with canagliflozin 100 and 300 mg and placebo, respectively. Osmotic diuresis-related AEs were more common with both canagliflozin doses, and incidences of urinary tract infections and volume depletion-related AEs were higher with canagliflozin 300 mg versus placebo. Decreases in eGFR (-2.1, -4.0 and -1.6 ml/min/1.73 m(2)) were seen with canagliflozin 100 and 300 mg compared with placebo. Canagliflozin 100 and 300 mg provided median percent reductions in urine albumin to creatinine ratio versus placebo (-16.4, -28.0 and 19.7%). CONCLUSIONS: Canagliflozin improved glycaemic control and was generally well tolerated in patients with T2DM and within a subset of Stage 3 CKD over 52 weeks.

Efficacy and safety of canagliflozin compared with placebo and sitagliptin in patients with type 2 diabetes on background metformin monotherapy: a randomised trial.

AIMS/HYPOTHESIS: The aim of this work was to evaluate the efficacy and safety of canagliflozin vs placebo and sitagliptin in patients with type 2 diabetes who were being treated with background metformin. METHODS: This randomised, double-blind, four-arm, parallel-group, Phase 3 study was conducted at 169 centres in 22 countries between April 2010 and August 2012. Participants (N = 1,284) with type 2 diabetes aged ≥ 18 and ≤ 80 years who had inadequate glycaemic control (HbA1c ≥ 7.0% [53 mmol/mol] and ≤10.5% [91 mmol/mol]) on metformin therapy received canagliflozin 100 mg or 300 mg, sitagliptin 100 mg, or placebo (n = 368, 367, 366, 183, respectively) for a 26 week, placebo- and active-controlled period followed by a 26 week, active-controlled period (placebo group switched to sitagliptin [placebo/sitagliptin]) and were included in the modified intent-to-treat analysis set. Randomisation was performed using a computer-generated schedule; participants, study centres and the sponsor were blinded to group assignment. The primary endpoint was change from baseline in HbA1c at week 26; secondary endpoints included changes in HbA1c (week 52) and fasting plasma glucose (FPG), body weight, and systolic blood pressure (BP; weeks 26 and 52). Adverse events (AEs) were recorded throughout the study. RESULTS: At week 26, canagliflozin 100 mg and 300 mg reduced HbA1c vs placebo (-0.79%, -0.94%, -0.17%, respectively; p < 0.001). At week 52, canagliflozin 100 mg and 300 mg demonstrated non-inferiority, and canagliflozin 300 mg demonstrated statistical superiority, to sitagliptin in lowering HbA1c (-0.73%, -0.88%,-0.73%, respectively); differences (95% CI) vs sitagliptin were 0% (-0.12, 0.12) and -0.15% (-0.27, -0.03), respectively. Canagliflozin 100 mg and 300 mg reduced body weight vs placebo (week 26: -3.7%, -4.2%, -1.2%, respectively; p < 0.001) and sitagliptin (week 52: -3.8%, -4.2%, -1.3%, respectively; p < 0.001). Both canagliflozin doses reduced FPG and systolic BP vs placebo (week 26) and sitagliptin (week 52) (p < 0.001). Overall AE and AE-related discontinuation rates were generally similar across groups, but higher with canagliflozin 100 mg. Genital mycotic infection and osmotic diuresis-related AE rates were higher with canagliflozin; few led to discontinuations. Hypoglycaemia incidence was higher with canagliflozin. CONCLUSIONS/INTERPRETATION: Canagliflozin improved glycaemia and reduced body weight vs placebo (week 26) and sitagliptin (week 52) and was generally well tolerated in patients with type 2 diabetes on metformin. CLINICAL TRIAL REGISTRY: ClinicalTrials.gov NCT01106677 FUNDING: This study was supported by Janssen Research & Development, LLC.

Efficacy and safety of canagliflozin monotherapy in subjects with type 2 diabetes mellitus inadequately controlled with diet and exercise.

AIMS: Canagliflozin is a sodium glucose co-transporter 2 inhibitor in development for type 2 diabetes mellitus (T2DM). The efficacy and safety of canagliflozin were evaluated in subjects with T2DM inadequately controlled with diet and exercise. METHODS: In this 26-week, randomized, double-blind, placebo-controlled, phase 3 trial, subjects (N = 584) received canagliflozin 100 or 300 mg or placebo once daily. Primary endpoint was the change from baseline in haemoglobin A1c (HbA1c) at week 26. Secondary endpoints included the proportion of subjects achieving HbA1c < 7.0%; change from baseline in fasting plasma glucose (FPG), 2-h postprandial glucose (PPG) and systolic blood pressure (BP); and percent change in body weight, high-density lipoprotein cholesterol (HDL-C) and triglycerides. Adverse events (AEs) were recorded throughout the study. RESULTS: At week 26, HbA1c was significantly reduced from baseline with canagliflozin 100 and 300 mg compared with placebo (-0.77, -1.03 and 0.14%, respectively; p < 0.001 for both). Both canagliflozin doses significantly decreased FPG, 2-h PPG, body weight and systolic BP (p < 0.001 for all), and increased HDL-C compared with placebo (p < 0.01 for both). Overall incidences of AEs were modestly higher with canagliflozin versus placebo; rates of serious AEs and AE-related discontinuations were low and similar across groups. Incidences of genital mycotic infections, urinary tract infections and osmotic diuresis-related AEs were higher with canagliflozin; these led to few discontinuations. The incidence of hypoglycaemia was low across groups. CONCLUSION: Canagliflozin treatment improved glycaemic control, reduced body weight and was generally well tolerated in subjects with T2DM inadequately controlled with diet and exercise.

Efficacy and safety of canagliflozin in subjects with type 2 diabetes and chronic kidney disease.

AIMS: Canagliflozin is a sodium glucose co-transporter 2 inhibitor in development for treatment of type 2 diabetes mellitus (T2DM). This study evaluated the efficacy and safety of canagliflozin in subjects with T2DM and stage 3 chronic kidney disease [CKD; estimated glomerular filtration rate (eGFR) ≥30 and <50 ml/min/1.73 m(2)]. METHODS: In this randomized, double-blind, placebo-controlled, phase 3 trial, subjects (N = 269) received canagliflozin 100 or 300 mg or placebo daily. The primary efficacy endpoint was change from baseline in HbA1c at week 26. Prespecified secondary endpoints were change in fasting plasma glucose (FPG) and proportion of subjects reaching HbA1c <7.0%. Safety was assessed based on adverse event (AE) reports; renal safety parameters (e.g. eGFR, blood urea nitrogen and albumin/creatinine ratio) were also evaluated. RESULTS: Both canagliflozin 100 and 300 mg reduced HbA1c from baseline compared with placebo at week 26 (-0.33, -0.44 and -0.03%; p < 0.05). Numerical reductions in FPG and higher proportions of subjects reaching HbA1c < 7.0% were observed with canagliflozin 100 and 300 mg versus placebo (27.3, 32.6 and 17.2%). Overall AE rates were similar for canagliflozin 100 and 300 mg and placebo (78.9, 74.2 and 74.4%). Slightly higher rates of urinary tract infections and AEs related to osmotic diuresis and reduced intravascular volume were observed with canagliflozin 300 mg compared with other groups. Transient changes in renal function parameters that trended towards baseline over 26 weeks were observed with canagliflozin. CONCLUSION: Canagliflozin improved glycaemic control and was generally well tolerated in subjects with T2DM and Stage 3 CKD.

Efficacy and safety of canagliflozin in patients with type 2 diabetes mellitus inadequately controlled with metformin and sulphonylurea: a randomised trial.

AIMS: Canagliflozin is a sodium glucose co-transporter 2 inhibitor developed for the treatment of type 2 diabetes mellitus (T2DM). This randomised, double-blind, placebo-controlled, Phase 3 study evaluated the efficacy and safety of canagliflozin as an add-on to metformin plus sulphonylurea in patients with T2DM. METHODS: Patients (N = 469) received canagliflozin 100 or 300 mg or placebo once daily during a 26-week core period and a 26-week extension. Prespecified primary end-point was change in HbA1c at 26 weeks. Secondary end-points included change in HbA1c at week 52 as well as proportion of patients achieving HbA1c < 7.0%, change in fasting plasma glucose (FPG) and systolic blood pressure, and per cent change in body weight, high-density lipoprotein cholesterol, and triglycerides (weeks 26 and 52). RESULTS: HbA1c was significantly reduced with canagliflozin 100 and 300 mg vs. placebo at week 26 (-0.85%, -1.06%, and -0.13%; p < 0.001); these reductions were maintained at week 52 (-0.74%, -0.96%, and 0.01%). Both canagliflozin doses reduced FPG and body weight vs. placebo at week 26 (p < 0.001) and week 52. Overall adverse event (AE) rates were similar across groups over 52 weeks, with higher rates of genital mycotic infections and osmotic diuresis-related AEs seen with canagliflozin vs. placebo; these led to few discontinuations. Increased incidence of documented, but not severe, hypoglycaemia episodes was seen with canagliflozin vs. placebo. CONCLUSIONS: Canagliflozin improved glycaemic control, reduced body weight, and was generally well tolerated in T2DM patients on metformin plus sulphonylurea over 52 weeks.

Modulation of calcium current in arteriolar smooth muscle by alphav beta3 and alpha5 beta1 integrin ligands.

Vasoactive effects of soluble matrix proteins and integrin-binding peptides on arterioles are mediated by alphav beta3 and alpha5 beta1 integrins. To examine the underlying mechanisms, we measured L-type Ca2+ channel current in arteriolar smooth muscle cells in response to integrin ligands. Whole-cell, inward Ba2+ currents were inhibited after application of soluble cyclic RGD peptide, vitronectin (VN), fibronectin (FN), either of two anti-beta3 integrin antibodies, or monovalent beta3 antibody. With VN or beta3 antibody coated onto microbeads and presented as an insoluble ligand, current was also inhibited. In contrast, beads coated with FN or alpha5 antibody produced significant enhancement of current after bead attachment. Soluble alpha5 antibody had no effect on current but blocked the increase in current evoked by FN-coated beads and enhanced current when applied in combination with an appropriate IgG. The data suggest that alphavbeta3 and alpha5 beta1 integrins are differentially linked through intracellular signaling pathways to the L-type Ca2+ channel and thereby alter control of Ca2+ influx in vascular smooth muscle. This would account for the vasoactive effects of integrin ligands on arterioles and provide a potential mechanism for wound recognition during tissue injury.

RGDN peptide interaction with endothelial alpha5beta1 integrin causes sustained endothelin-dependent vasoconstriction of rat skeletal muscle arterioles.

The ability of an integrin-binding Arg-Gly-Asp-Asn (RGDN)- containing peptide to influence vascular tone by interacting with the alpha5beta1 integrin was studied using rat skeletal muscle arterioles. After blockade of beta3 integrin function, isolated arterioles with spontaneous tone showed concentration-dependent vasoconstrictions to topical application of GRGDNP, a peptide that shows a greater ability to interact with alpha5beta1 than with alphavbeta3. The constriction to GRGDNP (2.1 mM) was inhibited by blocking alpha5 integrin function, and was intensified by blocking beta3 integrin function. In contrast, GRGDSP, a peptide that interacts better with alphavbeta3, was unable to induce sustained constrictions. Removal of the endothelium abolished the vasoconstriction in response to GRGDNP, suggesting that the response was due to release of an endothelium-dependent factor. Indeed, blockade of ETA endothelin receptors with BQ-610 (1 microM), similar to removal of the endothelium and alpha5 integrin blockade, inhibited the vasoconstriction. These data indicate that interaction of RGD peptides, and in particular the RGDN sequence with endothelial cell alpha5beta1, causes endothelin-mediated arteriolar vasoconstriction. These results indicate that integrins are novel signaling receptors within the vascular wall that affect vasomotor tone, and may play an important role in vascular control.

Unknown primary head and neck squamous cell carcinoma: molecular identification of the site of origin.

BACKGROUND: Unknown primary head and neck squamous cell carcinoma (HNSCC) presents as a cervical lymph node metastasis without identification of the primary tumor, despite thorough diagnostic work-up that includes physical examination, computed tomography, esophagoscopy, laryngoscopy, bronchoscopy, and multiple surveillance biopsies. We investigated whether the site of origin of the primary tumor could be localized in the upper aerodigestive tract mucosa by detection of genetic alterations identical to those found in metastatic lesions. METHODS: Microsatellite analysis was performed on metastatic tumors obtained from 18 patients with unknown primary HNSCC. Histologically benign surveillance biopsy specimens were also analyzed. Patients were followed up to 13 years with continuing surveillance for primary mucosal tumors. Most patients were treated with neck dissection followed by radiation therapy to the affected neck and ipsilateral Waldeyer's ring. RESULTS: In 10 (55%) of the 18 patients, at least one histopathologically benign mucosal biopsy specimen from defined anatomic sites (i.e., most likely sites for an occult primary tumor) demonstrated a pattern of genetic alterations identical to that present in cervical lymph node metastases. One patient harboring genetic alterations in the base of the tongue and two patients harboring genetic alterations in a tonsillar fossa subsequently developed HNSCC in the identical or adjacent mucosal region; all three of the primary head and neck mucosal tumors that eventually appeared between 1 and 13 years later in these patients had genetic changes identical to those in the benign mucosal biopsy specimens and in the metastatic lymph nodes. CONCLUSIONS: These data support the hypothesis that histopathologically benign mucosa of the upper aerodigestive tract may harbor foci of clonal, preneoplastic cells that are genetically related to metastatic HNSCC and that such mucosal sites are the sites of origin of unknown primary HNSCC. Microsatellite analysis may represent a clinically useful tool for determining such sites.

Detection of telomerase activity in oral rinses from head and neck squamous cell carcinoma patients.

Telomerase is a ribonucleoprotein that maintains telomere length and whose activity is associated with escape from cellular senescence. Telomerase activity has been found in germline, immortalized, and malignant tumor cells. Using a modified PCR-based assay for telomerase activity, 26 of 35 (80%) primary, fresh, head and neck squamous cell cancer specimens and 3 of 6 head and neck squamous dysplastic lesions possessed telomerase activity. In addition, 14 of 44 (32%) oral rinses from a separate group of head and neck squamous cell cancer patients contained detectable telomerase activity, whereas 1 of 22 (5%) oral rinses from normal control patients exhibited telomerase activity. Telomerase activity in oral rinses was compared with corresponding activity in paired primary tumor samples for 19 cases: 7 of 19 demonstrated activity in both tumor and oral rinse, 2 of 19 lacked activity in both tumor and oral rinse, 10 of 19 tumors demonstrated activity that could not be detected in corresponding oral rinses, and there were no examples of positive oral rinses with corresponding negative tumors. Although currently limited in its sensitivity, analysis of telomerase activity in oral rinses represents a novel method to detect the presence of cancer cells shed in the upper aerodigestive tract.

Impaired arteriolar myogenic reactivity in early experimental diabetes.

Hyperperfusion and an increase in capillary pressure has been implicated in the pathogenesis of diabetic microangiopathy. The existence of such alterations suggests that the myogenic response to increased intravascular pressure may be altered in diabetes. To examine this, in vivo studies were performed on the rat cremaster muscle microcirculation of age-matched control and STZ-induced (65 mg/kg) diabetic rats (3-4 wk of diabetes). Anesthetized rats were enclosed in an airtight Plexiglas box with the cremaster muscle exteriorized into an organ bath containing Krebs' solution. To study myogenic responsiveness, box pressure was increased in steps of 10 mmHg from 0 to 30 mmHg for 2 min. Third-order arterioles of the control animals (lumen diameter 18 +/- 2 microns) responded to increased pressure with a rapid onset vasoconstriction. In contrast, the rate of development of the constriction was markedly attenuated in similar vessels (15 +/- 1 micron) of the diabetic animals, despite their ability to exhibit a similar maximal arteriolar constriction to that of the control animals. When 20 mmHg pressure steps were applied for only 10 s, arterioles of the diabetic animals constricted minimally, whereas those of the control animals constricted to 75% of the maximal response expected for that pressure increase (P < 0.01). Second-order arterioles of both groups of animals responded with a primarily passive distension to increased intravascular pressure suggesting that the impaired responsiveness of the third-order arterioles is not compensated for by an increase in the myogenic responsiveness of upstream vessels. Basal intravascular pressures, measured in first-, second-, and third-order arterioles, were similar in control and diabetic animals.(ABSTRACT TRUNCATED AT 250 WORDS)

Genetic progression and clonal relationship of recurrent premalignant head and neck lesions.

We constructed a preliminary genetic progression model for head and neck squamous cell carcinoma (HNSC) based on the frequency of genetic alterations in preneoplastic and neoplastic lesions from single biopsy specimens. To firmly establish the temporal order of established genetic events in HNSC, we sampled serial biopsies from five patients with recurrent premalignant lesions at a single anatomic site over a period of time (1 month to 144 months). These lesions were examined by microsatellite analysis of the minimal regions of loss on the 10 most frequently lost chromosomal arms in HNSC. Each set of serial biopsies from all five patients demonstrated LOH (loss of heterozygosity) of identical alleles at multiple loci with identical boundaries between areas of LOH and retention of heterozygosity, indicating a common clonal origin for each set. Three patients demonstrated genetic progression (new regions of LOH) over time correlating with histopathological progression, one patient demonstrated lack of genetic progression associated with unchanged histopathological morphology, and one patient demonstrated histopathological progression without detection of a corresponding genetic progression event. For one of these patients with a laryngeal tumor, at least four separate steps in progression to malignancy could be determined, accompanied by spatial expansion of an increasingly altered clonal population from the ipsilateral to the contralateral side, ultimately resulting in a malignancy. Microsatellite-based genetic analysis of recurrent premalignant lesions indicates that these lesions arise from a common clonal progenitor, followed by outgrowth of clonal populations associated with progressive genetic alterations and phenotypic progression to malignancy.

A new paradigm for graduate research and training in the biomedical sciences and engineering.

98Emphasis on the individual investigator has fostered discovery for centuries, yet it is now recognized that the complexity of problems in the biomedical sciences and engineering requires collaborative efforts from individuals having diverse training and expertise. Various approaches can facilitate interdisciplinary interactions, but we submit that there is a critical need for a new educational paradigm for the way that we train biomedical engineers, life scientists, and mathematicians. We cannot continue to train graduate students in isolation within single disciplines, nor can we ask any one individual to learn all the essentials of biology, engineering, and mathematics. We must transform how students are trained and incorporate how real-world research and development are done-in diverse, interdisciplinary teams. Our fundamental vision is to create an innovative paradigm for graduate research and training that yields a new generation of biomedical engineers, life scientists, and mathematicians that is more diverse and that embraces and actively pursues a truly interdisciplinary, team-based approach to research based on a known benefit and mutual respect. In this paper, we describe our attempt to accomplish this via focused training in biomechanics, biomedical optics, mathematics, mechanobiology, and physiology. The overall approach is applicable, however, to most areas of biomedical research.

Transduction mechanisms involved in the regulation of myogenic activity.

Vascular smooth muscle has the ability to exist in a state of maintained partial constriction. This state of partial activation is initiated and/or maintained by the mechanical effects of distending pressure acting on the vascular wall. The intrinsic ability of vascular smooth muscle to respond to these mechanical forces is referred to as the myogenic mechanism. Within the past decade the signaling mechanisms responsible for mechanotransduction of myogenic phenomena have been the focus of extensive research. Two areas of active investigation include (1) the modulation of membrane ionic conductances by pressure/stretch and (2) the pressure/stretch-induced generation of second messengers known to be involved in vascular smooth muscle contraction. This review summarizes recent work aimed at understanding the mechanotransduction process in vascular smooth muscle.

Distributions of microvascular pressure in skeletal muscle of one-kidney, one clip, two-kidney, one clip, and deoxycorticosterone-salt hypertensive rats.

Studies were performed on the cremaster skeletal muscle in rats to investigate the microvascular changes that are associated with established one-kidney, one clip (1K1C) and two-kidney, one clip (2K1C) Goldblatt hypertension and with deoxycorticosterone (DOC)-salt hypertension. Rats were anesthetized with urethane and chloralose; and cremaster muscles with intact circulation and innervation were suspended in a controlled Krebs bath. Microvascular pressures and vessel diameters were measured at three consecutive arteriolar (A) and venular (V) branch levels. Arteriolar diameters (means +/- SEM) in normotensive (NT) rats were 119 +/- 7, 86 +/- 5, and 31 +/- 3 micron respectively for 1A, 2A, and 3A arterioles; and venule diameters were 218 +/- 12, 141 +/- 15, and 53 +/- 7 micron respectively for 1V, 2V, and 3V venules. As compared to NT rats, there was a selective decrease in lumen size (percent reduction from control) for 1A and 2A (23% to 38%) in 1K1C and 2K1C rats and for 1A, 2A, and 3A (42% to 44%) in DOC rats. Venule diameters were not significantly different between normotensive and hypertensive animals at any branch level. Femoral artery pressures were significantly elevated (greater than or equal to 43%) in all three forms of hypertension; however, this increase in pressure was not proportionally transmitted throughout the microcirculation. This was evidenced by normal pressure in 3A arterioles and in all venules for 1K1C and 2K1C rats and by normal pressures in 3V and larger venules for DOC rats. Our findings indicate that elevated arterial pressure in chronic renal hypertension is not transmitted uniformly across all microvascular segments.(ABSTRACT TRUNCATED AT 250 WORDS)