Novel diabetes mellitus treatment: mature canine insulin production by canine striated muscle through gene therapy

Muscle-targeted gene therapy using insulin genes has the potential to provide an inexpensive, low maintenance alternative or adjunctive treatment method for canine diabetes mellitus. A canine skeletal muscle cell line was established through primary culture, as well as through transdifferentiation of canine fibroblasts after infection with a myo-differentiation gene containing adenovirus vector. A novel mutant furin-cleavable canine preproinsulin gene insert (cppI4) was designed and created through de novo gene synthesis. Various cell lines, including the generated canine muscle cell line, were transfected with nonviral plasmids containing cppI4. Insulin and desmin immunostaining were used to prove insulin production by muscle cells and specific canine insulin ELISA to prove mature insulin secretion into the medium. The canine myoblast cultures proved positive on desmin immunostaining. All cells tolerated transfection with cppI4-containing plasmid, and double immunostaining for insulin and desmin proved present in the canine cells. Canine insulin ELISA assessment of medium of cppI4-transfected murine myoblasts and canine myoblast and fibroblast mixture proved presence of mature fully processed canine insulin, 24 and 48 h after transfection. The present study provides proof of principle that canine muscle cells can be induced to produce and secrete canine insulin on transfection with nonviral plasmid DNA containing a novel mutant canine preproinsulin gene that produces furin-cleavable canine preproinsulin. This technology could be developed to provide an alternative canine diabetes mellitus treatment option or to provide a constant source for background insulin, as well as C-peptide, alongside current treatment options.

Rapamycin toxicity in MIN6 cells and rat and human islets is mediated by the inhibition of mTOR complex 2 (mTORC2)

AIMS/HYPOTHESIS

Rapamycin (sirolimus) is one of the primary immunosuppressants for islet transplantation. Yet there is evidence that the long-term treatment of islet-transplant patients with rapamycin may be responsible for subsequent loss of islet graft function and viability. Therefore, the primary objective of this study was to elucidate the molecular mechanism of rapamycin toxicity in beta cells.

METHODS

Experiments were performed on isolated rat and human islets of Langerhans and MIN6 cells. The effects of rapamycin and the roles of mammalian target of rapamycin complex 2 (mTORC2)/protein kinase B (PKB) on beta cell signalling, function and viability were investigated using cell viability assays, insulin ELISA assays, kinase assays, western blotting, pharmacological inhibitors, small interfering (si)RNA and through the overproduction of a constitutively active mutant of PKB.

RESULTS

Rapamycin treatment of MIN6 cells and islets of Langerhans resulted in a loss of cell function and viability. Although rapamycin acutely inhibited mTOR complex 1 (mTORC1), the toxic effects of rapamycin were more closely correlated to the dissociation and inactivation of mTORC2 and the inhibition of PKB. Indeed, the overproduction of constitutively active PKB protected islets from rapamycin toxicity whereas the inhibition of PKB led to a loss of cell viability. Moreover, the selective inactivation of mTORC2 using siRNA directed towards rapamycin-insensitive companion of target of rapamycin (RICTOR), mimicked the toxic effects of chronic rapamycin treatment.

CONCLUSIONS/INTERPRETATION

This report provides evidence that rapamycin toxicity is mediated by the inactivation of mTORC2 and the inhibition of PKB and thus reveals the molecular basis of rapamycin toxicity and the essential role of mTORC2 in maintaining beta cell function and survival.

The use of kidneys with small renal tumors for transplantation: who is taking the risk?

The ever-increasing disparity between the number of organs available for transplant and the need for organs drives further exploration into the use of compromised or marginal donors. There is now an emerging advocacy for the use of kidneys with existing tumors, which may be rendered tumor free after surgical excision and reconstruction. This practice is based on reliable data that renal cancers <3 cm in diameter behave with minimal malignant potential and likelihood of transmission to the immunosuppressed recipient. However, in the case of live donors this creates a potential ethical conflict between those treating patients with renal masses and those with an interest in renal donation. The best available treatment for patients with a small renal tumor is a form of nephron-sparing tumor excision or ablation, as this approach provides for the maximum amount of residual kidney function and enhances survival. Thus, patients newly diagnosed with small renal tumors should be referred to centers with expertise in nephron sparing techniques, not transplant centers. In the case of an individual undergoing a live donor evaluation in which a small renal tumor is detected, a careful analysis of risk and benefit for the potential donor and the recipient is indicated.

Sunitinib in patients (pts) with unresectable primary renal cell carcinoma (RCC)

5096

Background: Sunitinib inhibits VEGF and related receptors, with high tumor shrinkage rates in metastatic (met) RCC. Shrinkage of primary tumors has been observed, although prospective investigation is lacking. The ability of sunitinib to convert primary RCC tumors from unresectable to resectable is of high clinical interest. Methods: Pts with histologically-confirmed RCC with an unresectable primary tumor with or without met disease were enrolled on a single-arm phase II trial. Primary tumors were unresectable due to ≥ 1 of the following: large tumor size, bulky lymphadenopathy, encasement of renal vessels, IVC thrombosis or proximity to vital structures. Pts received 50 mg sunitinib continuous dosing in repeated 6-week cycles. Staging by CT scans or MRI was done at baseline and every 2 cycles. A Simon 2-stage design was employed to test the alternative hypothesis of a conversion to resectability rate of 20% versus the null hypothesis of 5%; β = 0.8, α = 0.05 (n = 31). Results: 18 pts have been enrolled; 1 excluded due to a non-RCC diagnosis. Pts were unresectable due to bulky lymphadenopathy (6), IVC thrombosis (4), proximity to vital structures (4) or tumor size (3), although most pts had multiple factors. Median age among 14 evaluable pts was 61 years (range, 37–80), 59% male, 76% ECOG PS 0; 79% had distant met disease. The 14 evaluable pts have received a median of 3 cycles of therapy (range, 1–10+). Three pts (21%) have undergone primary tumor resection; viable RCC was identified in all specimens with no unexpected surgical morbidity. Nine pts (53%) had primary tumor reduction (median 19%; range, -64% to -1%). Overall, median best % change in tumor burden was 4.9% reduction for primary tumors (range, -43.1% to +8.5%) and 10.7% reduction for met sites (range, -89.5% to +28.6%). Median PFS is 4.9 months. Eleven pts (79%) discontinued therapy; 8 for PD, 1 for adverse events and 2 following surgery which removed all visible disease. Eight pts (57%) experienced grade 3 toxicity including thrombocytopenia, fatigue, hypertension, anemia, hemoptysis, and hand-foot syndrome; 1 pt had grade 4 neutropenia. Conclusions: Sunitinib has activity in unresectable primary RCC tumors, permitting resection in some pts. Continued prospective investigation is required to optimize patient selection and timing of surgery.

[Table: see text]

Inability to process and store proinsulin in transdifferentiated pancreatic acinar cells lacking the regulated secretory pathway

Generation of new beta-cells from the adult pancreas or the embryonic stem cells is being pursued by research groups worldwide. Success will be dependent on confirmation of true beta-cell phenotype evidenced by capacity to process and store proinsulin. The aim of these studies was to robustly determine endocrine characteristics of the AR42J rat pancreatic acinar cell line before and after in vitro transdifferentiation. beta-cell phenotypic marker expression was characterised by RT-PCR, immunostaining, western blotting, ELISA and in human preproinsulin transgene over-expression studies in wild-type AR42J cells and after culture on Matrigel basement membrane matrix with and without growth/differentiation factor supplementation. Pancreatic duodenal homeobox 1 (PDX1), forkhead box transcription factor a2 (Foxa2), glucokinase, pancreatic polypeptide and low-level insulin gene transcription in wild-type AR42J cells were confirmed by RT-PCR. Culture on Matrigel-coated plates and supplementation of medium with glucagon-like peptide 1 induced expression of the beta-cell Glut 2 with maintained expression of insulin and PDX1. Increased biosynthesis and secretion of proinsulin were confirmed by immunocytochemical staining and sensitive ELISA. Absence of the regulated secretory pathway was demonstrated by undetectable prohormone convertase expression. In addition, inability to process and store endogenous proinsulin or human proinsulin translated from a constitutively over-expressed preproinsulin transgene was confirmed. The importance of robust phenotypic characterisation at the protein level in attempted beta-cell transdifferentiation studies has been confirmed. Rodent and human sensitive/specific differential proinsulin/insulin ELISA in combination with human preproinsulin over-expression enables detailed elucidatation of core endocrine functions of proinsulin processing and storage in putative new beta-cells.

Nitric oxide stimulates insulin gene transcription in pancreatic β-cells

Recent studies have identified a positive role for nitric oxide (NO) in the regulation of pancreatic beta-cell function. The aim of this study was to determine the effects of short-term exposure to NO on beta-cell gene expression and the activity of the transcription factor PDX-1. NO stimulated the activity of the insulin gene promoter in Min6 beta-cells and endogenous insulin mRNA levels in both Min6 and isolated islets of Langerhans. Addition of wortmannin prior to NO stimulation blocked the observed increases in insulin gene promoter activity. Although NO addition stimulated the phosphorylation of p38, inhibition by SB203580 did not block the effect of NO on the insulin gene promoter. NO addition also stimulated both the nuclear accumulation and the DNA binding activity of PDX-1. This study has shown that over 24h, NO stimulates insulin gene expression, PI-3-kinase activity and the activity of the critical beta-cell transcription factor PDX-1.

Androgen receptor levels are increased by interferons in human prostate stromal and epithelial cells

Proliferation of normal and malignant prostate epithelium is regulated by androgen stimulation via both the androgen receptor (AR)-positive stromal and epithelial cells. However, it is not known how AR expression is regulated in human prostate cells. We report that treatment of normal human prostate stromal cells (PrSCs) with type I IFN (alpha or beta), but not type II IFN (gamma), resulted in increased levels of AR protein. The maximal increase in AR protein levels was dependent on the dose and the duration of the IFN-alpha treatment. We found that the increase in AR protein levels was independent of de novo transcription and protein synthesis. Interestingly, the IFN-alpha treatment of PrSCs resulted in considerable nuclear accumulation of AR, stimulation of AR-mediated transcription of reporter genes, and retardation of cell proliferation. Furthermore, treatment of normal human prostate epithelial cells with IFNs (alpha, beta or gamma) also resulted in increased levels of AR protein. Together, our observations identify the androgen receptor as an IFN-regulated protein in normal human prostate stromal and epithelial cells and predict that IFN-induced levels of AR in prostate cells contribute to the regulation of androgen signaling.

Effects of rosiglitazone and metformin on pancreatic beta cell gene expression

AIMS/HYPOTHESIS

Rosiglitazone and metformin are two oral antihyperglycaemic drugs used to treat type 2 diabetes. While both drugs have been shown to improve insulin-sensitive glucose uptake, the direct effects of these drugs on pancreatic beta cells is only now beginning to be clarified. The aim of the present study was to determine the direct effects of these agents on beta cell gene expression.

METHODS

We used reporter gene analysis to examine the effects of rosiglitazone and metformin on the activity of the proinsulin and insulin promoter factor 1 (IPF1) gene promoters in the glucose-responsive mouse beta cell line Min6. Western blot and gel retardation analyses were used to examine the effects of both drugs on the regulation of IPF1 protein production, nuclear accumulation and DNA binding activity in both Min6 cells and isolated rat islets of Langerhans.

RESULTS

Over 24 h, rosiglitazone promoted the nuclear accumulation of IPF1 and forkhead homeobox A2 (FOXA2), independently of glucose concentration, and stimulated a two-fold increase in the activity of the Ipf1 gene promoter (p<0.01). Stimulation of the Ipf1 promoter by rosiglitazone was unaffected by the presence of the peroxisome proliferator activated receptor gamma antagonist GW9662. No effect of either rosiglitazone or metformin was observed on proinsulin promoter activity. Metformin stimulated IPF1 nuclear accumulation and DNA binding activity in a time-dependent manner, with maximal effects observed after 2 h.

CONCLUSIONS/INTERPRETATION

Metformin and rosiglitazone have direct effects on beta cell gene expression, suggesting that these agents may play a previously unrecognised role in the direct regulation of pancreatic beta cell function.

Renal Tumors in Young Adults

PURPOSE

The clinical and pathological features of solid or complex cystic renal masses in young adults have not been defined. We present our experience with patients 17 to 45 years old with such renal masses to define the incidence of malignant vs benign lesions, familial tendencies and clinical outcomes.

MATERIALS AND METHODS

The medical records of all patients 17 to 45 years old who presented with a solid or suspicious complex cystic renal mass at 2 tertiary care hospitals between 1988 and 2002 were retrospectively reviewed. Pertinent clinical information was compiled, including age, gender, mode of presentation, renal function, year and type of surgery, pathological analysis and survival data.

RESULTS

There were 114 evaluable patients who underwent a total of 119 nephrectomies. Mean patient age was 37.1 years and males comprised 56.1% of the population. Twelve patients had familial renal cell carcinoma (RCC), the von Hippel-Lindau syndrome. Mode of presentation for patients with sporadic disease was symptomatic (55.9%), incidental (35.3%) or unknown (8.8%). Radical nephrectomy, partial nephrectomy and nephroureterectomy were performed in 80 kidneys (67.2%), 37 (31.1%) and 2 (1.7%), respectively. Malignant lesions comprised 79.8% of all masses and 95.8% of these were renal cell carcinoma. Of the RCCs 75.8% were grade 1 or 2 and 89% were organ confined. Young women were much more likely than men to have a benign lesion (36.0% vs 9.5%, p <0.01) and the diversity of histologies was impressive (of the 24 total benign masses 9 were different tumor types). With an average followup of 38.3 months overall survival is 90.2%. Among patients with RCC 84.9% are alive and cancer-free, 11.6% are dead from disease and 3.5% are alive with recurrent disease.

CONCLUSIONS

We report the largest known series of solid or suspicious complex renal masses in young adults. As expected, familial tumors are more common in this population. While RCC is the most common tumor, a wide variety of potential pathological outcomes are possible, particularly in women, who were much more likely to have a benign lesion. RCC in this patient population appears to have a favorable prognosis, despite symptomatic presentation in the majority of cases.

Thrombospondin-1, vascular endothelial growth factor and fibroblast growth factor-2 are key functional regulators of angiogenesis in the prostate

BACKGROUND

Prostate cells secrete many molecules capable of regulating angiogenesis; however, which of these actually function as essential regulators of neovascularization is not yet clear.

METHODS

Functional angiogenic mediators secreted by normal and diseased prostate cells were identified using an in vitro angiogenesis assay. These factors were quantified by immunoblot or ELISA and localized in tissue by immunohistochemistry.

RESULTS

Normal prostate epithelial cell secretions were anti-angiogenic due to inhibitory thrombospondin-1 (TSP-1) whereas this inhibitor was decreased in the pro-angiogenic secretions derived from benign prostatic hyperplasia (BPH) and cancer cells. This pro-angiogenic activity depended primarily on fibroblast growth factor-2 (FGF-2) and/or vascular endothelial growth factor (VEGF) whose secretion was increased. Immunolocalization studies confirmed that the changes detected in vitro also occurred in vivo.

CONCLUSIONS

During disease progression in the prostate, production of TSP-1, the major inhibitor, is down-regulated while that of stimulatory FGF-2 and/or VEGF rise, leading to the induction of the new vessels necessary to support tumor growth.

Hand-assisted vs. retroperitoneal laparoscopic nephrectomy

PURPOSE

We retrospectively compared our initial experience with the hand-assisted and retroperitoneal laparoscopic nephrectomy techniques to determine if there are important differences between these approaches.

PATIENTS AND METHODS

Twenty-four laparoscopic cases consisting of 12 hand-assisted and 12 retroperitoneal nephrectomies were compared. All cases but one were radical nephrectomies with intact specimen extraction performed for suspected stage T1 neoplasms. Data were collected from medical records and a postoperative questionnaire. To determine if significant learning curves existed, the first six nephrectomies in each group were compared with the second six nephrectomies on the basis of operative criteria. The two groups did not differ significantly in age, body mass index, ASA rating, or number of previous abdominal operations.

RESULTS

Although the mean tumor volume was greater in the hand-assisted group than the retroperitoneal group, the difference did not quite reach statistical significance (91.19 v 24.7 cc3; P = 0.06). The mean operative time, estimated blood loss, narcotic use (milligrams of intravenous morphine equivalent), hours to oral intake, hospital stay, and estimated percent activity at 2 weeks for the hand-assisted group (238.33 min, 293.75 mL, 35.7 mg, 17.56 hours, 4.4 days, 74.75%, respectively) were not significantly different from the values in the retroperitoneal group (255.83 min, 141.67 mL, 24.5 mg, 22.36 hours, 3.6 days, 76.91%). We found no significant difference in the mean operative times for the first and second six cases in either group.

CONCLUSION

In the initial experience and comparison of hand-assisted and retroperitoneal laparoscopic nephrectomy, we found no significant differences in operative time, estimated blood loss, narcotic usage, hours to oral intake, hospital stay, or activity level at 2 weeks postoperatively. A randomized trial is under way at our institution.

The role of hypoxia and p53 in the regulation of angiogenesis in bladder cancer

PURPOSE

Our previous studies defined thrombospondin-1 (TSP-1) and vascular endothelial growth factor (VEGF) as the primary mediators of angiogenesis in the bladder and the loss of inhibitory TSP-1 as a key event in the transition to an angiogenic phenotype during bladder cancer development. We evaluated the role of p53, which is commonly inactivated in bladder cancer, and hypoxia in the regulation of angiogenesis in the bladder.

MATERIALS AND METHODS

The p53 status was modulated in normal urothelial and bladder cancer cells, and conditioned media was collected under normal oxygen or hypoxic (0.5% O2) conditions. Angiogenic activity was evaluated with the endothelial cell migration assay, and the levels of secreted TSP-1 and VEGF were determined by Western blot analysis and enzyme-linked immunosorbent assay, respectively.

RESULTS

Retroviral mediated expression of the E6 oncoprotein reduced wild-type p53 levels in normal urothelial cells by greater than 90% but did not significantly alter TSP-1 or VEGF levels, while total inductive and inhibitory activities remained unchanged. Adenoviral mediated expression of wild-type p53 was confirmed in 4 bladder cancer cell lines by Western blot analysis for p53 and its downstream effector protein p21 (2.5 to 5.0-fold increase). TSP-1 levels remained unchanged but the levels of secreted VEGF in the high grade UMUC-3 and 253J cell lines were significantly decreased 5 to 50-fold and a corresponding decrease in net angiogenic activity was observed. However, (increased expression) of p53 had no effect on the angiogenic activity of the low grade RT4 or high grade HT1376 bladder cancer cells. Hypoxia converted normal urothelial cell derived conditioned media from anti-angiogenic to angiogenic and increased the angiogenic activity of bladder cancer cell derived conditioned media. This change was due to 2.5 to 6-fold hypoxic up-regulation of VEGF because the expression of inhibitory TSP-1 was not significantly altered.

CONCLUSIONS

Our results suggest that p53 does not regulate angiogenesis in the bladder in the setting of an otherwise normal genome and gene therapy with wild-type p53, which is currently being studied for this cancer, may have only limited effects on angiogenesis. In contrast, hypoxia regulates angiogenesis in this system, primarily through its effects on VEGF.

Biogenic production of cyanide and its application to gold recovery

Chromobacterium violaceum is a cyanogenic (cyanide-producing) microorganism. Cyanide is used on an industrial scale to complex and recover gold from ores or concentrates of ores bearing the precious metal. A potentially useful approach in gold mining operations could be to produce cyanide biologically in relatively small quantities at the ore surface. In this study, C. violaceum grown in nutrient broth formed a biofilm and could complex and solubilize 100% of the gold on glass test slides within 4-7 days. Approximately 50% of the cyanide- recoverable gold could be mobilized from a biooxidized sulfidic-ore concentrate. Complexation of cyanide in solution by gold appeared to have a beneficial effect on cell growth--viable cell counts were nearly two orders of magnitude greater in the presence of gold-coated slides or biooxidized ore substrates than in their absence. C. violaceum was cyanogenic when grown in alternative feedstocks. When grown in a mineral salt solution supplemented with 13.3% v/v swine fecal material (SFM), cells exhibited pigmentation and suspended cell concentrations comparable to cultures grown in nutrient broth. Glycine supplements stimulated production of cyanide in 13.3% v/v SFM. In contrast, glycine was inhibitory when added at the time of inoculation in the more concentrated SFM, decreasing cell numbers and reducing ultimate bulk-solution cyanide concentrations. However, aeration and addition of glycine to stationary phase cells grown on 13.3% v/v SFM anaerobically resulted in rapid production and high concentrations (up to 38 mg l(-1)) of cyanide. This indicates that biogenesis of cyanide may be supported in remote areas using locally produced and inexpensive agricultural feedstocks in place of commercial media.

Solitary fibrous tumor of the prostate a report of 2 cases and review of the literature

We report 2 cases of solitary fibrous tumor of the prostate. Histologically, both tumors demonstrated a multipatterned architecture with varying degrees of collagenization and hemangiopericytoma-like foci, and both were composed of CD34-immunopositive spindled cells that insinuated themselves between strips of collagen. The tumor in case 1 was well circumscribed and showed minimal mitotic activity or pleomorphism, whereas the tumor in case 2 was more cellular, less collagenous, had a more diffuse growth pattern, and exhibited cytologic atypia and high mitotic activity. Prostatic solitary fibrous tumor must be distinguished from other spindle cell tumors reported to occur in the prostate. To our knowledge, these cases represent only the fifth and sixth reported cases of prostatic solitary fibrous tumor.

Contemporary management of renal cell carcinoma with coexistent renal artery disease: update of the Cleveland Clinic experience

OBJECTIVES

To treat concurrent renal cell carcinoma (RCC) and renal artery disease (RAD), which pose an unusual and challenging management dilemma.

METHODS

Before June 1998, 48 patients presented with localized RCC and RAD affecting all the functioning renal parenchyma. These patients were grouped into four distinct categories: group 1, a solitary kidney with RCC and RAD (n = 8); group 2, bilateral RCC and coexistent RAD (n = 9); group 3, unilateral RCC and contralateral RAD (n = 15); and group 4, unilateral RCC and bilateral RAD (n = 16). The most common cause of RAD was atherosclerosis (n = 40), followed by medial fibroplasia (n = 5), renal artery aneurysm (n = 2), and arteriovenous malformation (n = 1).

RESULTS

All patients underwent complete surgical excision of RCC. A nephron-sparing operation was performed preferentially (44 patients), and bilateral renal cancer operations were staged. Eleven patients underwent surgical renal vascular reconstruction in conjunction with either partial (n = 9) or radical (n = 2) nephrectomy. In 2 patients, renal revascularization was accomplished by percutaneous transluminal angioplasty before tumor excision. No perioperative deaths occurred. Postoperatively, preservation of renal function was achieved in 47 patients; 1 patient required chronic dialysis. The overall and cancer-specific 5-year patient survival rates in this series were 66% and 90%, respectively. At a mean follow-up of 58 months, 28 patients were alive with no evidence of malignancy. Six patients died of metastatic RCC, and 14 died of unrelated causes with no evidence of malignancy.

CONCLUSIONS

Nephron-sparing surgery combined with selective renal arterial reconstruction can yield gratifying results in this complex patient population.

Clinical aspects of inhaled anticholinergic therapy

Anticholinergic therapy is directed toward muscarinic receptors within the lung. Inhaled quaternary muscarinic antagonists are used because they cause less systemic adverse effects than other types of antimuscarinic drugs. Of the 5 possible muscarinic receptors, the lung contains three: M1, M2, and M3. Antagonism of the M1 and M3 receptors results in bronchodilation, primarily in the larger airways. The efficacy of the antimuscarinic bronchodilators cannot be entirely explained by this mechanism, and there is probably peripheral activity as well. The use of inhaled antimuscarinic drugs is well tolerated, and the efficacy is maintained with chronic use. Although ipratropium is the first-line therapy for symptomatic COPD, it and other similar drugs can also be used to treat other obstructive diseases. Ipratropium is available in an MDI, in solution for small-volume nebulizer, and in combination with albuterol in an MDI. Newer antimuscarinic agents are being developed that are more selective for the M1 and M3 sites and last longer. Research is continuing to better understand the sites of action of these agents as well as to develop even more effective drugs.

Glucose regulates islet amyloid polypeptide gene transcription in a PDX1- and calcium-dependent manner

Islet amyloid polypeptide (IAPP) and insulin are expressed in the beta-cells of the islets of Langerhans. They are co-secreted in response to changes in glucose concentration, and their mRNA levels are also regulated by glucose. The promoters of both genes share similar cis-acting sequence elements, and both bind the homeodomain transcription factor PDX1, which plays an important role in the regulation of the insulin promoter and insulin mRNA levels by glucose. Here we examine the role of PDX1 in the regulation of the human IAPP promoter by glucose. The experiments were facilitated by the availability of a human beta-cell line (NES2Y) that lacks PDX1. NES2Y cells also lack operational K(ATP) channels, resulting in a loss of control of calcium signaling. We have previously used these cells to show that glucose regulation of the insulin gene is dependent on PDX1, but not calcium. In the mouse beta-cell line Min6, glucose (16 mm) stimulated a 3.5-4-fold increase in the activity of a -222 to +450 IAPP promoter construct compared with values observed in 0.5 mm glucose. In NES2Y cells, glucose failed to stimulate transcriptional activation of the IAPP promoter. Overexpression of PDX1 in NES2Y cells failed to reinstate glucose-responsive control of the IAPP promoter. Glucose effects on the IAPP promoter were observed only in the presence of PDX1 when normal calcium signaling was restored by overexpression of the two K(ATP) channel subunits SUR1 and Kir6.2. The importance of calcium was further emphasized by an experiment in which glucose-stimulated IAPP promoter activity was inhibited by the calcium channel blocker verapamil (50 microm). Verapamil was further shown to inhibit the stimulatory effect of glucose on IAPP mRNA levels. These results demonstrate that like the insulin promoter, glucose regulation of the IAPP promoter is dependent on the activity of PDX1, but unlike the insulin promoter, it additionally requires the activity of another, as yet uncharacterized factor(s), the activity of which is calcium-dependent.

Inhibitory effect of pax4 on the human insulin and islet amyloid polypeptide (IAPP) promoters

Pax4 is a paired-box transcription factor that plays an important role in the development of pancreatic beta-cells. Two Pax4 cDNAs were isolated from a rat insulinoma library. One contained the full-length sequence of Pax4. The other, termed Pax4c, was identical to Pax4 but lacked the sequences encoding 117 amino acids at the COOH-terminus. Pax4 was found to inhibit the human insulin promoter through a sequence element, the C2 box, located at -253 to -244, and the islet amyloid polypeptide promoter through a sequence element located downstream of -138. The inhibitory activity of Pax4 was mapped to separate regions of the protein between amino acids 2-230 and 231-349.

Renal cryosurgery: experimental evaluation of treatment parameters

OBJECTIVES

Cryosurgery represents a minimally invasive alternative for the management of small or equivocal lesions of the kidney. We evaluated the relationship between ultrasonographic appearance and intrarenal temperatures and the effect of renal artery occlusion on the efficacy of the freezing process in a canine model.

METHODS

Ten animals were treated with intraparenchymal cryoablative therapy with (n = 5) or without (n = 5) renal artery occlusion using a rapid freeze technique. Intrarenal temperatures were measured 1.0 cm away from the cryoprobe at various times during the freezing process. The distance from the cryoprobe to the ice ball as monitored by ultrasonography was also determined. The contralateral kidney was removed to facilitate studies of renal function and all animals were killed on day 28 for autopsy and histopathologic examination.

RESULTS

A target temperature of less than -20 degrees C was achieved 3.1 mm behind the ice ball in all animals tested. The ice ball stabilized at a radius of 16 mm with prolonged treatment, suggesting that multiple probes will be required to treat renal lesions greater than 2.5 cm in diameter. Renal artery occlusion did not significantly alter the freezing process and provided no practical advantage. Renal function remained stable (final serum creatinine level 1.5 mg/dL or less) in all but 1 animal in which an obstructive stricture of the ureteropelvic junction developed. Effective tissue ablation was confirmed at the treatment site in all instances.

CONCLUSIONS

Renal cryoablative therapy is a nephron-sparing modality that can be delivered in a safe, efficacious, and reproducible manner. The treatment parameters defined in this study should allow for intelligent patient selection and rational administration of renal cryotherapy.

Molecular mediators of angiogenesis in bladder cancer

Bladder tumors are characterized by markedly increased angiogenesis when compared to the normal urothelium (NU) from which they are derived. Here, we use both cultured cells and immunohistochemistry to demonstrate a primary regulatory role for thrombospondin-1 (TSP-1), a potent inhibitor of angiogenesis, in the development of bladder tumor angiogenesis. Secretions from bladder cancer (CA) cells stimulated endothelial cell migration and corneal neovascularization, whereas those from NU cells were inhibitory. The antiangiogenic activity of NU cells was primarily due to secreted TSP-1 because neutralizing antibodies completely relieved the inhibition. Neutralizing antibodies to several putative angiogenesis inducers identified vascular endothelial growth factor (VEGF) and, to a lesser extent, basic fibroblast growth factor as the primary inducers secreted by bladder cancer cells. The secretion of TSP-1 by low- and high-grade cancer cells was reduced >94% when compared to NU cells, and this loss of inhibitory TSP-1 accounted for the development of an angiogenic phenotype because both NU cells and cancer cells secreted similar levels of total stimulatory activity and VEGF. Immunohistochemistry showed that TSP-1 was significantly reduced in all grades of bladder cancer when compared to NU, whereas VEGF staining remained relatively constant. Taken together, these data suggest that down-regulation of TSP-1 secretion is a key event in the switch from an antiangiogenic to an angiogenic phenotype, which occurs early in the development of bladder cancer.

Advances in angiogenesis research: relevance to urological oncology

PURPOSE

Important advances in angiogenesis research are reviewed along with recent data implicating angiogenesis in the pathogenesis of urological malignancies.

MATERIALS AND METHODS

The current understanding of angiogenesis and its importance in tumor biology is summarized. The rationale for anti-angiogenic therapy is reviewed and the clinical experience with these agents is discussed. An extensive literature search of angiogenesis in urological malignancies was performed.

RESULTS

Quantitative immunohistochemistry for endothelial antigens suggests that, as is the case with many other tumors, induction of angiogenesis contributes to the malignant phenotype of prostate and bladder carcinomas. Anti-angiogenic agents have demonstrated efficacy against urological tumors in experimental systems, and recent data suggest that these agents may also be useful for chemoprophylactic purposes. Putative angiogenesis inducers specific for each of the major urological malignancies have been identified. Quantitation of the expression of angiogenesis inducers and estimation of microvessel density have demonstrated prognostic value for urological malignancies.

CONCLUSIONS

The available data indicate that angiogenesis has an important role in the progression and metastasis of urological malignancies. Preclinical data coupled with experience in other cancers indicate that combining anti-angiogenic therapy with conventional treatment modalities has the potential to improve dramatically our management of these malignancies. Further research will be needed to define the mechanisms controlling angiogenesis in urological malignancies and to determine if any of the angiogenic correlates will be of genuine clinical use. The rapid pace of research in this field suggests that this aspect of tumor biology will soon have an increasingly important role in the evaluation and treatment of urological cancers.

Prospective evaluation of fine needle aspiration of small, solid renal masses: accuracy and morbidity

OBJECTIVES

To determine the accuracy and clinical utility of fine needle aspiration (FNA) of small, solid renal masses.

METHODS

A total of 25 patients with small (less than 5.0 cm), solid, clinically localized renal masses were prospectively identified and evaluated with computed tomography guided FNA with analysis for presence of malignant cells and determination of nuclear grade. The final pathologic findings were used for comparison in each case. All patients had renal cell carcinoma and were managed with radical or partial nephrectomy; 3 had low-grade lesions (Fuhrman's grade 1/4), 2 had high-grade lesions (Fuhrman's grade 4/4), and all other patients had intermediate-grade lesions (Fuhrman's grade 2/4 or 3/4) on final histopathologic assessment.

RESULTS

Overall, 10 aspirations yielded diagnostic malignant cells, and 9 were read as rare as rare atypical cells suspicious for malignancy. The remainder were negative (n = 6). Correlation with final nuclear grade was observed in eight instances and discordance in two instances. Subcapsular hematomas were observed at the time of surgery in 10 patients, but in no instance was the operation adversely affected.

CONCLUSIONS

The diagnostic yield of FNA of small, solid renal masses appears to be too low to justify the potential morbidity of the procedure.

Patterns of tumor recurrence and guidelines for followup after nephron sparing surgery for sporadic renal cell carcinoma

PURPOSE

We delineated patterns of tumor recurrence and developed guidelines for followup after nephron sparing surgery for sporadic renal cell carcinoma.

MATERIALS AND METHODS

Before December 1994, 327 patients underwent nephron sparing surgery for sporadic localized renal cell carcinoma at our clinic. Mean postoperative followup was 55.6 months. The course and outcome for patients with postoperative recurrent renal cell carcinoma were reviewed in detail.

RESULTS

Renal cell carcinoma recurred after nephron sparing surgery in 38 patients (11.6%), including 13 (4.0%) who had local tumor recurrence with (7) or without (6) metastatic disease and 25 (7.6%) who had metastatic disease without local tumor recurrence. Recurrent renal cell carcinoma was detected by associated symptoms in 25 patients and by a followup chest x-ray or abdominal computerized tomography (CT) in 13. The respective incidences of postoperative local tumor recurrence and metastatic disease according to initial pathological tumor stage were 0 and 4.4% for stage T1, 2.0 and 5.3% for stage T2, 8.2 and 11.5% for stage T3a, and 10.6 and 14.9% for stage T3b disease. The peak postoperative intervals until local tumor recurrence were 6 to 24 months (7 of 10 patients with stage T3 renal cell carcinoma) and longer than 48 months (all 3 with stage T2 disease). Patients with isolated local tumor recurrence had better survival compared to those with local tumor recurrence and metastatic disease or metastases only.

CONCLUSIONS

Followup for recurrent malignancy after nephron sparing surgery for renal cell carcinoma can be tailored according to the initial pathological tumor stage. All patients should be evaluated yearly with a medical history, physical examination and select laboratory studies. Patients with stage T1 renal cell carcinoma require no additional monitoring, while those with stage T2 disease should also undergo a yearly chest x-ray and abdominal CT every 2 years. The same recommendations are offered for patients with stage T3 renal cell carcinoma except that abdominal CT should be done every 6 months for the first 2 years postoperatively.

Molecular regulation of intercellular adhesion molecule 1 (ICAM-1) expression in renal cell carcinoma

Intercellular adhesion molecule-1 (ICAM-1) mediates two important functional aspects of tumor biology, namely enhancement of tumor metastasis and mediation of host defense mechanisms such as lymphocyte-mediated tumor cytotoxicity. Since ICAM-1 is expressed by most renal cell carcinomas (RCC), the regulation of ICAM-1 expression is important in understanding the biological behavior of RCC. We report an investigation on ICAM-1 expression and molecular regulation by cytokines and protein kinase C activator on RCC cell lines. Of the various cytokines, tumor necrosis factor alpha (TNF alpha), interferon-gamma (IFN gamma), and phorbol myristate acetate (PMA) strongly upregulated ICAM-1 protein expression on RCC. The kinetics of ICAM-1 message induction was studied by Northern analysis of total RNA extracted from RCC and normal kidney proximal tubular (NKPT) cells. Time course studies showed that ICAM-1 mRNA was upregulated by INF gamma, TNF alpha, and PMA, plateaued after 2 h, and remained increased for up to 24 h. Although ICAM-1 mRNA in NKPT cells was upregulated by these cytokines, their messages returned to basal levels after 24 h. ICAM-1 mRNA stability assays showed that both unstimulated and stimulated RCC cells had very stable ICAM-1 mRNA up to 24 h. In order to investigate whether increased gene transcription contributes to ICAM-1 upregulation, RCC cells were treated with TNF alpha, IFN gamma, or PMA with or without simultaneous addition of actinomycin D. ICAM-1 message induction-blocking studies suggested that primary upregulation of ICAM-1 mRNA may be caused by transcriptional upregulation. These results suggest that long-lasting ICAM-1 message upregulation in response to cytokines or PMA may be due to transcriptional upregulation in the early phase and stabilization of ICAM-1 message in the later phase (after 4 h). These observations suggest that RCC may lack the normal downregulatory mechanisms which control ICAM-1 expression and may explain the high frequency of ICAM-1 expression observed on primary human RCC.

Intraoperative evaluation of renal cell carcinoma: a prospective study of the role of ultrasonography and histopathological frozen sections

PURPOSE

Nephron sparing surgery is being performed increasingly for treatment of renal cell carcinoma, including in select patients with a normal contralateral kidney. The number of tumors in the involved kidney (single versus multiple) and presence or absence of perinephric fat involvement (pathological stage T1 to 2 versus T3A) are important prognostic factors. In a prospective study we evaluated the accuracy of intraoperative histopathological frozen section analysis of renal capsular biopsies for assessing local tumor stage, and the accuracy of intraoperative ultrasonography for assessing tumor focality.

MATERIALS AND METHODS

Intraoperative frozen section biopsies and ultrasonography were compared with information obtained from preoperative computerized tomography (CT), intraoperative inspection of the kidney by the surgeon and permanent histopathological specimens.

RESULTS

We evaluated 99 patients (102 kidneys) with localized sold renal masses undergoing either radical nephrectomy (48) or nephron sparing surgery (54). Final pathological analysis revealed 95 renal cell carcinomas (stage T3A in 24), 6 oncocytomas and 1 angiomyolipoma. Multiple tumors were detected in 18 of 102 kidneys overall. Frozen section analysis identified 87% of the stage T3A lesions with no false-positive results, compared to CT, which only identified 67%. Ultrasonography identified 14 of 18 multifocal tumors (78%) and was not more accurate than the combination of CT and intraoperative inspection. However, during nephron sparing surgery ultrasonography was useful to localize the intrarenal extent of tumors (17 cases).

CONCLUSIONS

Our results clarify the role of intraoperative ultrasonography and frozen section analysis in patients undergoing nephron sparing surgery for renal cell carcinoma. Frozen section analysis may be useful in select patients with small peripheral tumors who are under consideration for elective nephron sparing surgery.

Surgical technique and morbidity of elective partial nephrectomy

Nephron-sparing surgery (NSS) is being increasingly employed for the management of patients with localized renal cell carcinoma (RCC) and a normal opposite kidney. Ideally, such an approach should be reserved for patients in whom the risk of local recurrence and morbidity related to NSS are relatively low. In this article, we will review the technical considerations associated with performing elective partial nephrectomy and discuss the surgical complications specifically related to NSS, with emphasis on prevention, diagnosis, and management. Recent improvements in our technique for performing NSS will be described, and the current data regarding proper patient selection for elective partial nephrectomy will be reviewed.

Open pelvic lymph node dissection for prostate cancer: a reassessment

OBJECTIVES

To provide a risk-to-benefit analysis of open staging pelvic lymph node dissection (PLND) for prostate cancer.

METHODS

The medical records of all patients presenting with prostate cancer from July 1989 to April 1994 were reviewed. A total of 245 patients with clinically localized disease were selected to undergo radical retropubic prostatectomy (RRP) preceded by open PLND. Univariate and multivariate analyses were performed to evaluate the predictive value of the preoperative serum prostate-specific antigen (PSA) concentration, clinical stage, and Gleason score with regard to final nodal status. The cost and morbidity associated with PLND in the setting of RRP was also defined.

RESULTS

Overall, only 16 patients (6.5%) had lymph node metastases. Lymph node involvement correlated significantly with elevated serum PSA values (P = 0.0001), high Gleason score (P = 0.0022), and advanced clinical stage (P = 0.0001). Lymph node metastases were particularly uncommon in patients with nonpalpable tumors (1 of 67 [1.5%]), PSA values less than 10 (2 of 154 [1.3%]), and Gleason score less than 6 (1 of 26 [3.8%]). Overall, 179 patients (73.1%) presented with at least one or more of these favorable characteristics, and only 4 (2.2%) had lymph node involvement. Complications related to the lymphadenectomy occurred in 10 patients (4.1%). The cost per metastasis diagnosed in patients with low-risk characteristics was approximatley $43,600.

CONCLUSIONS

An open staging PLND may no longer be justified on a routine basis in patients undergoing radical retropubic prostatectomy.

Management of local recurrence following radical nephrectomy or partial nephrectomy

Surgical excision remains the preferred form of treatment for isolated local recurrence of RCC. Involvement of contiguous organs is not uncommon for local recurrence after radical nephrectomy, and en bloc excision can be a formidable task. Local recurrence after partial nephrectomy is more likely to occur as an isolated event, and many of these patients can be salvaged with repeat partial nephrectomy or total excision of the renal remnant. Local recurrence appears to be particularly common in patients with VHL disease; repeat surgical excision has yielded encouraging results in this setting. Unfortunately, we still have little to offer patients with local recurrence associated with disseminated disease. Improved forms of systemic or adjunctive therapy will be necessary for the treatment of these patients.

Complications of nephron sparing surgery for renal tumors

The technical results of 259 nephron sparing operations for renal cell carcinoma or renal oncocytoma were reviewed. Local or renal related complications occurred after 78 procedures (30.1%). The incidence of complications was less for operations performed after 1988 (22% versus 37%, p = 0.009) and for incidentally detected versus suspected tumors (p = 0.009). The most common complications were urinary fistula formation (45 operations) and acute renal failure (33). Significant predisposing factors for urinary fistula formation included central tumor location (p = 0.001), tumor size greater than 4 cm. (p = 0.001), the need for major reconstruction of the collecting system (p = 0.001) and ex vivo surgery (p = 0.001). Only 1 urinary fistula required open operative repair, while the remainder resolved either spontaneously (30) or with endoscopic management (14). Significant predisposing factors for acute renal failure included a solitary kidney (p = 0.001), tumor size greater than 7 cm. (p = 0.008), greater than 50% parenchymal excision (p = 0.001), greater than 60 minutes of ischemia time (p = 0.035) and ex vivo surgery (p = 0.001). Acute renal failure resolved in 28 patients, of whom 9 required temporary dialysis, while 5 required permanent dialysis. Overall, 8 complications (3.1%) required repeat open surgery for treatment while all other complications resolved with noninterventive or endourological management. Surgical complications contributed to an adverse clinical outcome in only 7 patients (2.9%). Nephron sparing surgery can be performed safely with preservation of renal function in most patients with renal tumors.

Intercellular adhesion molecule-1 expression by bladder cancer cells: functional effects

The role of intercellular adhesion molecule-1 (ICAM-1) and its ligand, leukocyte function-associated antigen-1 (LFA-1), in the interaction between bladder cancer cells and lymphokine activated killer (LAK) cells was investigated. Expression and modulation of ICAM-1 by cytokine treatment was assessed by immunocytometry and Northern blot analysis. Four of five human bladder cancer cell lines expressed ICAM-1 constitutively and responded to cytokine stimulation. Expression of ICAM-1 was upregulated most consistently by treatment with interferon-gamma (IFN gamma) and tumor necrosis factor-alpha (TNF alpha), cytokines that are released into the urine after intravesical BCG treatment. In contrast, interleukin-1 and phorbol myristate acetate exhibited variable effects on ICAM-1 expression, and interferon-alpha had no effect. The adherence of LAK cells to bladder cancer cell monolayers and LAK cell-mediated cytolysis were then studied. Monoclonal antibodies to ICAM-1 and LFA-1 significantly decreased the binding of LAK cells to the cell lines that express ICAM-1 (37 to 75% reduction, p < 0.05), and cytokine treatment (IFN gamma, TNF alpha) of these cells enhanced ICAM-1 dependent adherence (18 to 39% increase, p < 0.05). In contrast, these manipulations had no effect on the binding of LAK cells to the UMUC3 cell line, which does not express ICAM-1. Monoclonal antibodies to LFA-1 decreased LAK cell mediated cytolysis of the bladder cancer cells from 27 to 65% (p < 0.05), but anti-ICAM-1 antibodies were much less effective (0 to 25% decrease in cytolysis). Cytokine treatment (IFN gamma, TNF alpha) of the tumor cells did not significantly increase LAK cell-mediated cytolysis, despite upregulation of ICAM-1. These data demonstrate that ICAM-1 plays a role in the binding of LAK cells to bladder cancer cells but is only marginally involved in the process of LAK cell-mediated cytolysis. These findings suggest that adhesion molecules may be important mediators of the immune response to bladder cancer after intravesical BCG therapy.

Percutaneous management of transplant ureteral fistulas: patient selection and long-term results

Of 24 renal allograft recipients with urinary extravasation 14 (58%) with ureteral fistulas were selected for percutaneous management in an attempt to obviate secondary operative intervention. The initial procedure in all cases was placement of a percutaneous nephrostomy tube with subsequent internal or internal/external stenting. With a mean followup of 47 months, the percutaneous management proved definitive in 5 patients (36%) and palliative in 1 (7%). The other 8 patients (57%) subsequently required open operative intervention. With this study, we conclude that percutaneous techniques can provide long-term definitive management for at least some transplant ureteral fistulas. However, even in a highly selected group of patients success rates will be limited.

Management of renal cell carcinoma with coexistent renal artery disease

Coexistence of renal cell carcinoma and renal artery disease is an unusual and challenging problem. From 1969 to 1991, 34 patients presented with localized renal cell carcinoma and renal artery disease affecting all of the functioning renal parenchyma. These patients represented 4 categories: 1) a solitary kidney with renal cell carcinoma and renal artery disease (5), 2) bilateral renal cell carcinoma and coexistent renal artery disease (5), 3) unilateral renal cell carcinoma and contralateral renal artery disease (13), and 4) unilateral renal cell carcinoma and bilateral renal artery disease (11). Atherosclerosis was the most common cause of renal artery disease (30), followed by medial fibroplasia (2), renal artery aneurysm (1) and arteriovenous malformation (1). A total of 23 patients (68%) presented with azotemia (serum creatinine 1.5 mg./dl. or more) and 11 (32%) presented with hypertension. All patients underwent complete surgical excision of renal cell carcinoma. A nephron sparing operation was performed preferentially (30 patients) and bilateral renal cancer operations were staged. Eight patients underwent simultaneous partial (6) or radical (2) nephrectomy and surgical renal revascularization. There were no operative deaths. Postoperatively, preservation of renal function was achieved in 33 patients and 1 required chronic dialysis. At mean followup of 47 months 23 patients (68%) were alive with no evidence of malignancy and 2 were alive with recurrent renal cell carcinoma. Three patients died of metastatic renal cell carcinoma, while 6 died of unrelated causes. All of the latter 6 patients were free of renal cell carcinoma at death. Nephron sparing surgery combined occasionally with renal arterial reconstruction can yield gratifying results in this complex patient population.

Combined radical retropubic prostatectomy and proctosigmoidectomy for en bloc removal of locally invasive carcinoma of the rectum

A novel technique of combined radical retropubic prostatectomy and restorative proctosigmoidectomy is described, and indications and expected complications are discussed. It is offered as an alternative to total pelvic exenteration for patients with carcinoma of the rectum exhibiting isolated extension to the prostate gland or seminal vesicles. This procedure obviates the need for urinary and fecal diversion and provides excellent exposure for optimal rectal dissection. Thus, it offers the opportunity for improved functional results without compromising the principles important for local tumor control.

Delayed allograft autotransplantation after excision of a large symptomatic renal artery pseudoaneurysm

Pseudoaneurysm formation, which occurs infrequently in the renal transplant patient, can have a catastrophic outcome. We report a case of a large, symptomatic transplant renal artery pseudoaneurysm that was treated by excision with extracorporeal vascular repair and delayed allograft autotransplantation. We review the management of transplant renal artery pseudoaneurysms and the role of delayed autotransplantation in complex reconstructive renal surgery.

Initiation of chondroitin sulfate biosynthesis: a kinetic analysis of UDP-D-xylose: core protein beta-D-xylosyltransferase

The nature of the primary signals important for the addition of xylose to serines on the core protein of the cartilage chondroitin sulfate proteoglycan has been investigated. The importance of consensus sequence elements (Acidic-Acidic-Xxx-Ser-Gly-Xxx-Gly) in the natural acceptor was shown by the significant decrease in acceptor capability of peptide fragments derived by digestion of deglycosylated core protein with Staphylococcus aureus V8 protease, which cleaves within the consensus sequence, compared to the similar reactivity of trypsin-derived peptide fragments, in which consensus sequences remain intact. A comparison of the acceptor efficiencies (Vmax/Km) of synthetic peptides containing the proposed xylosylation consensus sequence and the natural acceptor (deglycosylated core protein) was then made by use of the in vitro xylosyltransferase assay. The two types of substrates were found to have nearly equivalent acceptor efficiencies and to be competitive inhibitors of each other's acceptor capability, with Km = Kiapparent. These results suggest that the artificial peptides containing the consensus sequence are analogues of individual substitution sites on the core protein and allowed the kinetic mechanism of the xylosyltransferase reaction to be investigated, with one of the artificial peptides as a model substrate. The most probable kinetic mechanism for the xylosyltransferase reaction was found to be an ordered single displacement with UDP-xylose as the leading substrate and the xylosylated peptide as the first product released. This represents the first reported formal kinetic mechanism for this glycosyltransferase and the only one reported for a nucleotide sugar:protein transferase.

The measurement of nonelastic work of breathing using a commercially available respiratory integrator

The authors compared real-time, breath-by-breath work of breathing (WOB) measurements made with a Hewlett-Packard 8815A respiratory integrator with nonelastic WOB values obtained by planimetry of pressure-volume tracings. They measured WOB while normal subjects breathed through a low-resistane mouthpiece. The integrator-derived values for WOB correlated well with planimeter-derived values (r = 0.97). Valid measurements of nonelastic WOB can be made at the bedside in realtime using the Hewlett-Packard 8815A without the addition of custom-built circuitry or hardware.

Deglycosylation of chondroitin sulfate proteoglycan and derived peptides

In order to define the domain structure of proteoglycans as well as identify primary amino acid sequences specific for attachment of the various carbohydrate substituents, reliable techniques for deglycosylating proteoglycans are required. In this study, deglycosylation of cartilage chondroitin sulfate proteoglycan (CSPG) with minimal core protein cleavage was accomplished by digestion with chondroitinase ABC and keratanase, followed by treatment with anhydrous HF in pyridine. Nearly complete deglycosylation of secreted proteoglycan was verified within 45 min of HF treatment by loss of incorporated [3H]glucosamine label from the proteoglycan as a function of time of treatment, as well as by direct analysis of carbohydrate content and xylosyltransferase acceptor activity of unlabeled core protein preparations. The deglycosylated CSPG preparations were homogeneous and of high molecular weight (approximately 370,000). Comparison of the intact deglycosylated core protein preparations with newly synthesized unprocessed precursors (apparent Mr approximately 360,000) suggested that extensive proteolytic cleavage of the core protein did not occur during normal intracellular processing. Furthermore, peptide patterns generated after clostripain digestion of core protein precursor and of deglycosylated secreted proteoglycan were comparable. With the use of the clostripain digestion procedure, peptides were produced from unlabeled proteoglycan, and two predominant peptides from the most highly glycosylated regions (the chondroitin sulfate rich regions of the proteoglycan) were isolated, characterized, and deglycosylated. These peptides were found to follow similar kinetics of deglycosylation and to acquire xylose acceptor activity comparable to the intact core protein.

Continuous transtracheal oxygen delivery during cardiopulmonary resuscitation. An alternative method of ventilation in a canine model

Adequate oxygenation of apneic subjects can be maintained by constant flow transtracheal oxygen (TTO), but this method alone is associated with hypercapnia. The "bellows" effect of external chest compressions (ECC) might prevent this problem if the airway were kept open by TTO. In dogs, we investigated the utility of TTO delivered at 15 L/min by a percutaneously placed intratracheal catheter, plus ECC (TTO/ECC) as an alternative method of ventilation during CPR. TTO was applied to anesthetized, paralyzed dogs in normal sinus rhythm (NSR) at various rates of ECC and during ventricular fibrillation (VF) at an ECC rate of 80/min. During NSR and VF, hypercapnia did not develop and arterial oxygen saturations were maintained above 90 percent. During NSR, the PaCO2 decreased and the pH increased as the ECC rate increased. For many of the animals, coronary perfusion pressure remained above 20 mm Hg during VF, suggesting that these animals could be resuscitated to NSR. In another phase, after 15 min of VF using TTO/ECC, seven of nine animals were defibrillated. We conclude that ventilatory and hemodynamic support adequate to permit successful resuscitation to NSR is provided by the combination of TTO/ECC to apneic dogs during VF.

Comparison of standard weaning parameters and the mechanical work of breathing in mechanically ventilated patients

Standard bedside criteria of respiratory mechanical capability and the mechanical work of spontaneous breathing were measured in 17 mechanically ventilated patients. Eleven patients were extubated within 24 hs of study and required only a brief period of mechanical ventilation (group 1). Group 2 consisted of six patients requiring more prolonged ventilator support. Group 1 patients met three of four bedside criteria; seven patients met all four. Five of six patients in group 2 also satisfied three of four standard criteria while ventilator-dependent, whereas only two patients satisfied all four when successfully weaning. As group 2 patients progressed from unsuccessful to successful weaning there was no consistent improvement in bedside criteria; however, measures of work did significantly improve. Hence, satisfaction of bedside mechanical weaning criteria is associated with weaning success in patients requiring brief mechanical ventilation. In patients requiring prolonged ventilation, work may be a better indicator of successful weaning.

Kinetics of intracellular processing of chondroitin sulfate proteoglycan core protein and other matrix components

Pulse-chase labeling techniques are used in conjunction with subcellular fractionation and quantitative immunoprecipitation to define the kinetics of intracellular translocation and secretion of proteoglycan core protein, along with link protein and type II collagen. In embryonic chick chondrocytes the core protein is processed very rapidly, exhibiting a t 1/2 in both the rough endoplasmic reticulum and golgi region of less than 10 min. Link protein appears to be processed as rapidly as the core protein, but the kinetics of type II collagen secretion is 3-4 times slower. These results are consistent with possible segregation and coordinate intracellular processing of link protein and core protein, macromolecules which are known to associate extracellularly. In contrast, rat chondrosarcoma chondrocytes translocated and secreted the core protein much more slowly (t 1/2 = 40 min) than the chick cells, perhaps due to the significantly reduced levels of galactosyltransferase I observed in the transformed chondrocytes.

Evaluation of whole blood theophylline enzyme immunochromatography assay

A new whole blood enzyme immunochromatographic (EIC) theophylline assay was evaluated in 18 low (25 to 37 percent) and 15 high hematocrit (49 to 56 percent) samples. A good correlation was observed between EIC and fluorescence polarization methods for plasma samples (r = 0.95). However, comparison of results between EIC whole blood and plasma values demonstrates a significant proportional bias that is inversely related to the sample's hematocrit. The EIC method for whole blood samples may substantially underestimate theophylline levels in polycythemic patients with theophylline values near or above the toxic range and underestimate levels in those with anemia, if a correction is not made for the sample's hematocrit. A correction formula to approximate plasma theophylline concentrations from whole blood measurements is described.

A comparison of albuterol and metaproterenol nebulizer solutions

Metaproterenol (15 mg) and albuterol (5 mg) solutions were each nebulized and delivered to 20 patients with reversible airway obstruction utilizing intermittent positive pressure ventilation in a double-blind comparison. Ten subjects were randomly assigned to each group and they were examined at the start (day 0) and at the end of the study (day 7). There were no significant differences observed between the spirometric responses or the untoward effects of the two groups to either agent. Albuterol and metaproterenol, when administered by intermittent positive pressure ventilation, are essentially equivalent in terms of the magnitude and duration of the response.

Dose-response study of nebulized bitolterol mesylate solution in asthmatic patients

Bitolterol mesylate, a new beta 2 adrenergic bronchodilator, is a "pro-drug" which is activated by esterases in the lung. In order to determine the optimal bronchodilator dose of bitolterol, six doses, (0.5 mg, 1.0 mg, 1.5 mg, 2.0 mg, 2.5 mg and 3.0 mg), were administered by closed-port, intermittent-flow nebulization (CPIF) to asthmatic patients on different days. For most patients, the onset of bronchodilator activity (FEV1 increase of at least 15 percent above baseline) occurred within 5 minutes and lasted at least 8 hours. Maximum mean increases in FEV1 were 46-50 percent at the 1.0 mg to 3.0 mg doses. Beyond the 1.0 mg dose, there was no significant improvement in bronchodilator effect, but adverse effects, particularly tremor, increased at higher doses. The optimal dose of bitolterol administered by CPIF was determined to be 1.0 mg which is similar to the dose of bitolterol recommended for use by metered-dose inhaler (MDI) which is 0.7 mg to 1.1 mg. If continuous-flow nebulization is used, two-three times more drug may be needed for a comparable effect. Bitolterol appears to be a safe, effective and long-lasting bronchodilator when administered by jet nebulization.