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Biomedical subjects

L S Machan

Publications and source records attributed to L S Machan.

At least 19 recordsLinked to original sources
PubMed2001

Complete inhibition of intimal hyperplasia by perivascular delivery of paclitaxel in balloon-injured rat carotid arteries.

PURPOSE: To determine whether perivascular delivery of paclitaxel prevents luminal narrowing after balloon injury by inhibiting intimal hyperplasia. MATERIALS AND METHODS: Immediately after balloon injury of the entire left common carotid artery, three slow-release formulations of paclitaxel or control formulations without drug were applied around a distal segment of the artery. The noninjured right carotid arteries were evaluated as a control. The animals were maintained for 14 and 28 days (n = 5 in each group at each time interval). Histology, immunohistochemistry, and morphometric analysis were performed. RESULTS: Injured nontreated arteries exhibited a pronounced intimal hyperplasia (0.185 +/- 0.01 mm2 at 14 days and 0.189 +/- 0.01 mm2 at 28 days) and a marked reduction in luminal area (44% at 14 days and 43% at 28 days). Medial area and the number of medial cells increased by 44% and 45%, respectively, at 14 days, and by 22% and 37%, respectively, at 28 days. Injured arteries treated with perivascular paclitaxel did not show any intimal hyperplasia, and luminal area was increased in five of six groups and was unchanged in one group. These arteries had an increased medial area but they had fewer medial cells than noninjured arteries. Injured arteries treated with control implants without paclitaxel exhibited intimal hyperplasia and luminal narrowing. CONCLUSION: Perivascular slow release of paclitaxel totally inhibits intimal hyperplasia and prevents luminal narrowing after balloon injury. Because of its efficacy, perivascular paclitaxel represents a possible approach for prevention of restenosis in humans.

Angiogenesis Inhibitors↗
PubMed2001

Treatment of type II endoleaks with Onyx.

Endoleaks are defined as persistent perfusion of an abdominal aortic aneurysm (AAA) after endovascular stent-graft deployment. The authors describe their experience treating six endoleaks with the liquid embolic agent Onyx (ethylene-vinyl-alcohol copolymer). Complete endoleak occlusion was achieved in five of six cases. Follow-up imaging has demonstrated decreased aneurysm diameter in all patients 7-29 weeks (mean = 19.2 weeks) after treatment.

Aged↗
PubMed2000

Paclitaxel loaded poly(L-lactic acid) microspheres for the prevention of intraperitoneal carcinomatosis after a surgical repair and tumor cell spill.

A controlled release delivery system for paclitaxel was developed using poly(L-lactic acid) to provide local delivery to the peritoneal cavity. Microspheres were made in 1-40 and 30-120 microm size ranges. In an in vitro release study, 30-120 microm microspheres loaded with 10, 20 and 30% paclitaxel exhibited a burst phase of release for 3 days followed by an apparently zero-order phase of release. At all loadings, 20-25% of the original load of paclitaxel was released after 30 days. The effect of microsphere size on retention in the peritoneal cavity was assessed. Control 1-40 microm microspheres were injected intraperitoneally in rats. The rats received either insufflation of the peritoneal cavity using 11 mmHg CO2 or no further treatment. After sacrifice, microspheres with diameters less than 24 microm were observed in the lymphatic system after being cleared from the peritoneal cavity through fenestrations in the diaphragm. Insufflation of the peritoneal cavity had no effect on the size of microspheres that were cleared. Efficacy studies were carried out using 30-120 microm microspheres that were of sufficient size to be retained in the peritoneal cavity. In a model of a tumor cell spill after a cecotomy repair, 100 mg of 30-120 microm microspheres containing 30% paclitaxel were effective in preventing growth of tumors in the peritoneal cavity at both 2 and 6 weeks post-surgery. No gross or histologically evident tumor growth was observed on any peritoneal surfaces or in the surgical wound site. Rats receiving control microspheres all showed tumor cell implantation and growth after 2 weeks.

Animals↗
PubMed1999

Post-surgical shunt hepatopulmonary syndrome in a case of non-cirrhotic portal hypertension: lack of efficacy of shunt reversal.

Hepatopulmonary syndrome, a consequence of significant liver disease and portal hypertension, is thought to be secondary to the effects of vasoactive substances, normally inactivated in the liver, on the pulmonary vasculature. We report a patient with preserved hepatic function who underwent a decompressive surgical porto-systemic shunt for non-cirrhotic portal hypertension. This patient developed hepatopulmonary syndrome with dyspnoea and oxygen desaturation 2 years post-surgical shunt. Over the next 7 years, the patient's respiratory function became increasingly impaired although hepatic function remained preserved. Because of the hypothesized role of porto-systemic shunting in the aetiology of this syndrome, the surgical shunt was successfully reversed angiographically. No improvement in dyspnoea or oxygen saturation occurred and liver transplantation was undertaken. Six months post-transplant, the patient has decreased his oxygen requirements and is free of dyspnoea. Our experience supports the causal role of porto-systemic shunting in the pathogenesis of hepatopulmonary syndrome but suggests that merely decreasing the extent of porto-systemic shunting is not beneficial. Liver transplantation remains the only reliable therapeutic modality available to these patients.

Adult↗
PubMed1998

Complex uterine surgery: a cooperative role for interventional radiology with hysteroscopic surgery.

OBJECTIVE: To describe the value of concurrent interventional radiology with hysteroscopy for the management of complex intrauterine abnormalities. DESIGN: A new descriptive technique. SETTING: Tertiary care center. PATIENT(S): Three case reports. INTERVENTION(S): Interventional radiology with the placement of guidewires and/or dilatation of resistant structures may assist with hysteroscopic management of complex intrauterine abnormalities or may be a primary therapeutic option. MAIN OUTCOME MEASURE(S): Resolution of dysmenorrhea and restoration of fertility. RESULT(S): The placement of a guidewire into an occluded portion of the intrauterine cavity provides direction and safety for hysteroscopic resolution of the underlying problem. In the last case, placement of the guidewire and passing dilators over the guidewire provided complete treatment. CONCLUSION(S): The uterine cavity or a smaller segment of it may be blocked by occlusive fibrous tissue that is not amenable to standard hysteroscopic dissection. Combining radiologic imaging with hysteroscopic surgery allows visual access to instrumentation and the hidden structures or organs throughout the entire procedure. It adds complexity to the surgery but may allow restoration of function to an organ or structure that is otherwise inaccessible.

Adolescent↗
PubMed1998

The talent endoluminal AAA stent-graft system. Report of the phase I USA trial, and summary of worldwide experience.

In the United States, the Phase I Feasibility Study under IDE G970065 was approved by the Food and Drug Administration on 04/11/97. The approved protocol called for implantation of the bifurcated Talent spring stent-graft system on patients who are high-risk candidates for conventional surgery because of cardio-respiratory, medical, general, or local anatomical reasons which would likely complicate the technical execution of the operation or be accompanied by a high expected mortality rate. Patient enrollment was complete with 16 cases as of September 26, 1997. This was a multicenter experience involving five different sites. This is an ongoing study and patients, of course, will continue to be followed longitudinally. Phase II will likely be approved by the FDA for initiation in January or February of 1998. Standard-risk AAA patients will be entered into the study at this time; comparison with concurrent controls will be used for comparison with conventional surgery.

Adult↗
PubMed1997

Endoscopic transvaginal approach to the rabbit uterine cervix: improvement in the technique of selective tubal catheterization.

RATIONALE AND OBJECTIVES: The authors compared two methods of selective fallopian tube catheterization in female rabbits. METHODS: Technical success rates and procedure times in two groups of animals were compared. Group 1 consisted of 20 female rabbits catheterized with a fluoroscopic technique. Group 2 consisted of 55 rabbits catheterized with a combination of endoscopic and fluoroscopic guidance. RESULTS: The technique used in group 2 allowed a statistically significant reduction in the time required for cervical catheterization and the total procedural time (P < .01). There was a parallel statistically significant reduction in fluoroscopy time (P < .01). Technical success rates and adverse effects were similar for the two techniques. CONCLUSION: The combined endoscopic-fluoroscopic technique requires a shorter time than the established fluoroscopic technique and should be considered for future selective tubal catheterization experiments in rabbits.

Animals↗
PubMed1997

Comparison of two-dimensional time-of-flight dynamic magnetic resonance angiography with digital subtraction angiography in popliteal artery entrapment syndrome.

OBJECTIVE: To assess dynamic magnetic resonance angiography (MRA) as an alternative to catheter angiography in patients with popliteal artery entrapment syndrome (PAES). PATIENTS AND METHODS: Nine patients with surgically proven PAES underwent provocation digital subtraction angiography (DSA) and 2-dimensional time-of-flight dynamic MRA of the popliteal fossae (total of 17 limbs). Eight normal volunteers also underwent dynamic MRA (total of 16 limbs). Two observers blinded to the surgical findings and the results of DSA independently evaluated the 33 limbs of the 17 subjects on the basis of maximum-intensity projection images and transverse MRA source images. The degree of stenosis was graded and compared with that indicated by DSA. RESULTS: Among the 17 limbs of patients with surgically proven PAES, dynamic MRA suggested the correct diagnosis in 13 (76%) by indicating stenosis greater than 50%. Dynamic MRA indicated stenosis of 1% to 50% for 4 (25%) of the 16 normal limbs and no stenosis in the other 12 normal limbs (i.e., no false positive results). CONCLUSION: Catheter angiography is not necessary if dynamic MRA indicates stenosis of greater than 50% in patients with clinical suspicion of PAES, but is recommended if dynamic MRA indicates stenosis of 1% to 50%.

Adolescent↗
PubMed1994

Photodynamic therapy for atherosclerotic stenoses in Yucatan miniswine.

OBJECTIVE: To determine the feasibility of treating atherosclerotic stenoses with photodynamic therapy (PDT). DESIGN: A prospective study with a 4-week follow-up. SUBJECTS: Twelve Yucatan miniswine, weighing between 25 and 35 kg. INTERVENTIONS: Aortoiliac atherosclerosis was created by a combination of balloon endothelial injury and dietary supplementation with 2% cholesterol and 15% lard for 7 weeks. Then the miniswine were given a porphyrin-type photosensitizer (Photofrin), 2.5 mg/kg intravenously, and treated with 630 nm light through an intravascular, cylindrical, diffusing fibreoptic probe, which was coupled to an argon-pumped dye laser to supply 120 J of laser energy. MAIN OUTCOME MEASURES: Differences in luminal narrowing before and after PDT. RESULTS: Seven miniswine had an increase in luminal diameter, but five had no increase. Microscopy demonstrated a broad range of features in treated vessels, including areas with re-endothelialization and regions of platelet and blood cell adherence with absent or abnormal endothelium. CONCLUSION: Although this study demonstrated resolution in stenoses for some miniswine, questions concerning light dosimetry, mechanism of action and long-term effects remain to be determined.

Animals↗
PubMed1993

Comparison of percutaneous with intra-operative balloon angioplasty for arteriosclerotic occlusive disease.

The purpose of this study was to compare the technical success and short-term outcome of intraoperative balloon angioplasty (IBA) with percutaneous transluminal angioplasty (PTA) in the iliac and femoropopliteal segment. From January 1988 to February 1991, 99 consecutive patients underwent 114 angioplasties in the iliac (37 PTA, 26 IBA) and femoropopliteal segment (15 PTA, 36 IBA). Mean age and sex distributions were similar between the groups. Claudication was the primary indication for both groups. All patients who underwent IBA had another concomitant surgical procedure performed. Immediate technical success for PTA and IBA were 50/52 (96%) and 58/62 (94%), respectively. Cumulative patency up to 12 months following angioplasty of the iliac artery was 94% for PTA and 78% for IBA (P-value NS). For the femoropopliteal segment, 12 month patency results were 100% for PTA and 78% for IBA (P-value NS). Complications requiring surgical intervention occurred in 3 (6%) PTA and 5 (8%) IBA cases. Results from this study indicate that technical success and early patency are similar for PTA and IBA in the iliac and femoropopliteal segments. However angioplasty-related complications were not avoided by performing balloon angioplasty in the operating room.

Aged↗
PubMed1992

Atherectomy. Early use of three different methods.

The authors report their initial experience in 52 patients with three different techniques of peripheral artery atherectomy--the Tracwright (Kensey), used in 19 patients, the Simpson AtheroCath, used in 19 patients and the transluminal extraction catheter, used in 14 patients. The indications for atherectomy were claudication in 42 (80%) and limb-threatening ischemia in 10 (19%). There were no deaths. Complications included three arterial perforations, one thrombosis and one groin hematoma requiring operative evacuation. There were no distal embolizations. Atherectomy was initially unsuccessful in 15 (29%) patients. For the successfully completed procedures, the 1-year primary patency rates were as follows: Tracwright (Kensey) catheter 56%, Simpson catheter (63%) and transluminal extraction catheter (0%). Use of subsequent nonoperative procedures on recurrent stenoses produced secondary patency rates of 77% for the Tracwright (Kensey) technique, 80% for the Simpson catheter technique and 78% for the transluminal extraction catheter technique. The authors conclude that their early results justify further evaluation of these three techniques. Use of the transluminal extraction catheter is associated with higher rates of occlusion and restenosis.

Aged↗
PubMed1989

Bladder outflow tract obstruction and urinary retention from benign prostatic hypertrophy treated by balloon dilatation.

Forty-eight men with urodynamically proven bladder outflow tract obstruction (BOO) and 19 with retention secondary to benign prostatic hypertrophy were treated by balloon dilatation of the prostate as out-patients; 31 were dilated with 20 mm and 36 with 25 mm balloons. Of the 48 men with BOO, 37 had repeat cystometrograms at intervals ranging from 3 to 11 months after dilatation and 33 (89%) remained obstructed by urodynamic criteria. Of 6 who only had a peak flow rate assessment, 5 had a flow less than 12 ml/s. Of the 19 patients in retention only 3 were able to void and all are obstructed. Symptoms of hesitancy, poor stream, frequency and nocturia were improved in less than 50% of patients. No reliable correlation was found between objective response and balloon size, length of time of dilatation, prostate size or morphology, detrusor pressure or stability, or post-dilatation urethrogram appearances. Balloon dilatation to 25 mm is not adequate therapy for bladder outflow tract obstruction or urinary retention from prostatic hypertrophy.

Catheterization↗
PubMedDate not supplied

Salpingitis isthmica nodosa: technical success and outcome of fluoroscopic transcervical fallopian tube recanalization.

PURPOSE: To evaluate the technical success and outcome of fallopian tube recanalization (FTR) in salpingitis isthmica nodosa (SIN). METHODS: SIN is a well-recognized pathological condition affecting the proximal fallopian tube and is associated with infertility and ectopic pregnancy. We reviewed the presentations, films, and case records of all patients attending for FTR for infertility from 1990 to 1994. Technical success and total, intrauterine, and ectopic pregnancy rates at follow-up were determined. RESULTS: SIN was observed in 22 of 349 (6%) patients. FTR was attempted in 34 tubes in these 22 patients. Technical success was achieved in 23 of 34 (68%) tubes affected by SIN. In 5 of the 11 failed recanalizations, failure was due to distal obstruction. At least one tube was patent on selective postprocedural salpingography in 17 of 22 (77%) patients. There were no recorded perforations or complications. At follow-up (mean 14 months), total, intrauterine, and ectopic pregnancy rates were 23%, 18%, and 4.5%, respectively. CONCLUSION: FTR in SIN is technically successful and, compared with previously reported results in unselected infertility patients, is associated with only a slightly less favorable intrauterine pregnancy rate and a comparable ectopic pregnancy rate. The findings of SIN at FTR should not discourage attempted fluoroscopic transcervical recanalization.

Adult↗
PubMedDate not supplied

Tubal sterilization by means of selective catheterization: comparison of a hydrogel and a collagen glue.

PURPOSE: To test, in an animal model, two potentially suitable materials for nonsurgical selective tubal sterilization. MATERIALS AND METHODS: A hydrogel that forms an in situ plug by phase inversion of a polymer solution was placed in four rabbit fallopian tubes, and a proprietary collagen glue was placed into three rabbit fallopian tubes by means of transvaginal fluoroscopic fallopian tube catheterization. As controls, 11 tubes were catheterized without sterilization material injection. The rabbits were bred, and the presence of embryos was confirmed with palpation and at autopsy. Histologic analysis was performed. RESULTS: The short-term contraception rate was 100% in the hydrogel group, 33% in the collagen glue group, and 0% in the control group (P < .001 hydrogel group, P not significant in collagen group). Inflammation was minimal in the three groups (P not significant). CONCLUSION: The collagen glue had an insufficient contraceptive effect and should be abandoned. The hydrogel used proved effective and biocompatible, and long-term studies of this compound are warranted.

Acrylonitrile↗