Biomedical subjects

L G Martin

Publications and source records attributed to L G Martin.

At least 37 records · Page 2Linked to original sources

PubMed1999

The role of education in explaining and forecasting trends in functional limitations among older Americans.

Using the Survey of Income and Program Participation, we document the importance of education in accounting for declines in functional limitations among older Americans from 1984 to 1993. Of the eight demographic and socioeconomic variables considered, education is most important in accounting for recent trends. The relationship between educational attainment and functioning has not changed measurably, but educational attainment has increased greatly during this period. Our analysis suggests, all else being equal, that future changes in education will continue to contribute to improvements in functioning, although at a reduced rate.

Activities of Daily Living↗

PubMed1998

Cost efficacy of duplex surveillance and prophylactic angioplasty of arteriovenous ePTFE grafts.

Poor patency of arteriovenous ePTFE grafts remains a major clinical problem. Prophylactic balloon angioplasty of stenoses has been claimed to prolong graft patency and has been widely introduced into practice. In this manuscript we report the cost incurred in application of such a program involving graft surveillance and prophylactic angioplasty of ePTFE graft stenoses >50% diameter. All patients in a single dialysis unit with ePTFE bridge grafts were subject to a surveillance duplex ultrasound and those with a perigraft stenosis of >50% then underwent angiography. Those patients confirmed to have a stenosis >50% within the graft, were randomized to prophylactic percutaneous transluminal angioplasty (PTA) versus no intervention (observation). Patients were followed every 3 months with ultrasound and those in the treatment group with recurrent stenosis (>50%) were subject to repeat PTA. The outcome was thrombosis. Relevant charges were considered to be: initial duplex screening of the entire ePTFE dialysis group; professional and technical fees for angiography and angioplasty; follow-up duplex scanning; repeat angioplasty; and costs of lytic therapy for an intraprocedure lysis. In the treatment and observation group the 6-month patencies were 69% +/- 7% and 70% +/- 7%, respectively. Twelve-month patencies for the treatment and observation groups were 51% +/- 6% and 47% +/- 4%. There was no significant difference between these two groups (p = 0.97), with an 80% confidence limit for detection of a difference >20%. Cost for duplex screening of all patients in the dialysis unit with ePTFE grafts was $40,440 (@ $337 each x 120 patients). Total charges for initial angiography was $178. Angioplasty charges were $143,040. Cost of the follow-up duplex ultrasound scanning in the treated group was $32,352. Charges for repeat angiograms in those with recurrent stenoses were $83,682 (professional fee $1733 + $229; technical fee + $820; equipment charges x 32 x 0.94). One patient required urokinase therapy for an occlusion following PTA. The overall charge for treating the 32 patients in the treatment arm of this study was $440,834, there was net improvement in patency. A policy of generic graft surveillance and prophylactic is expensive and does not lead to improved patency. Until an effective intervention is defined by prospective randomized trial, surveillance duplex scanning cannot be justified.

Angioplasty, Balloon↗

PubMed1998

Hypercalcemia and hypermagnesemia.

Hypercalcemia and hypermagnesemia occur infrequently in small animal patients. Specific clinical signs usually do not accompany these electrolyte disorders, and their presence is often recognized only after reviewing serum chemistry profile results. The etiologies, clinical signs, and therapies for each electrolyte disorder are discussed in this article. Treatment of these disorders is aimed at correcting the underlying disease process and enhancing the removal of calcium or magnesium from the body. In severe cases, rescue therapies and resuscitative measures are required to stabilize the patient.

Animals↗

PubMed1998

Disruption of the G1/S transition in human papillomavirus type 16 E7-expressing human cells is associated with altered regulation of cyclin E.

The development of neoplasia frequently involves inactivation of the p53 and retinoblastoma (Rb) tumor suppressor pathways and disruption of cell cycle checkpoints that monitor the integrity of replication and cell division. The human papillomavirus type 16 (HPV-16) oncoproteins, E6 and E7, have been shown to bind p53 and Rb, respectively. To further delineate the mechanisms by which E6 and E7 affect cell cycle control, we examined various aspects of the cell cycle machinery. The low-risk HPV-6 E6 and E7 proteins did not cause any significant change in the levels of cell cycle proteins analyzed. HPV-16 E6 resulted in very low levels of p53 and p21 and globally elevated cyclin-dependent kinase (CDK) activity. In contrast, HPV-16 E7 had a profound effect on several aspects of the cell cycle machinery. A number of cyclins and CDKs were elevated, and despite the elevation of the levels of at least two CDK inhibitors, p21 and p16, CDK activity was globally increased. Most strikingly, cyclin E expression was deregulated both transcriptionally and posttranscriptionally and persisted at high levels in S and G2/M. Transit through G1 was shortened by the premature activation of cyclin E-associated kinase activity. Elevation of cyclin E levels required both the CR1 and CR2 domains of E7. These data suggest that cyclin E may be a critical target of HPV-16 E7 in the disruption of G1/S cell cycle progression and that the ability of E7 to regulate cyclin E involves activities in addition to the release of E2F.

Cells, Cultured↗

PubMed1998

Understanding trends in functional limitations among older Americans.

OBJECTIVES: This report documents trends in functional limitations among older Americans from 1984 to 1993 and investigates reasons for such trends. METHODS: We applied logistic regression to data for noninstitutionalized Americans aged 50 years and older from the Survey of Income and Program Participation. We focused on 4 functional limitation measures unlikely to be affected by changes in role expectations and living environments: reported difficulty seeing words in a newspaper, lifting and carrying 10 pounds, climbing a flight of stairs, and walking a quarter of a mile. RESULTS: We found large declines in the crude prevalence of functional limitations, especially for those 80 years and older. Generally, changes in population composition explained only a small portion of the downward trends. Once changes in population composition and mobility-related device use were considered for difficulty walking, significant improvements in functioning remained for the 65- to 79-year-old group. CONCLUSIONS: Changes in population composition, device use, survey design, role expectations, and living environments do not appear to account completely for improvements in functioning. We infer that changes in under-lying physiological capability--whether real or perceived--likely underlie such trends.

Activities of Daily Living↗

PubMed1997

Prophylactic balloon angioplasty fails to prolong the patency of expanded polytetrafluoroethylene arteriovenous grafts: results of a prospective randomized study.

PURPOSE: Maintenance of hemodialysis access grafts represents an enormous social and clinical problem. Current grafts and graft salvage techniques are inadequate. Consequently, there has been increasing interest in the use of minimally invasive catheter techniques to prophylactically treat stenoses in functioning arteriovenous grafts. Prophylactic balloon angioplasty has been widely suggested as prolonging assisted primary patency. We have performed a prospective randomized trial to compare patients who underwent percutaneous transluminal angioplasty (PTA) for graft stenoses > 50% with a control group that received no intervention. Our hypothesis was that to be efficacious a minimal benefit of 20% prolongation in patency would be necessary. METHODS: Color flow duplex scanning was used to detect > 50% stenoses in functioning expanded polytetrafluoroethylene grafts. Patients were then subjected to confirmatory angiographic evaluation. Those who had angiographic stenoses > 50% were randomized to balloon angioplasty or observation. Patients were followed-up with duplex scanning every 2 months. Statistical analysis was performed using the Kaplan-Meier technique. Although demographically the patient groups were well matched, there were more prior interventions and concurrent central stenoses in the treatment group. Outcomes were graft thrombosis, graft dysfunction that precluded dialysis, and six or more PTA procedures within 18 months. RESULTS: In the treatment and observation groups, the 6-month patency rates were 69% +/- 7% and 70% +/- 7%, respectively. The 12-month patency rates for the treatment and observation groups were 51% +/- 6% and 47% +/- 4%, respectively. There was no significant difference between these two groups (p = 0.97), with an 80% confidence limit for detection of a difference greater than 20%. CONCLUSIONS: This study demonstrates that a generic approach of PTA to treat all polytetrafluoroethylene grafts with stenoses > 50% does not prolong patency and cannot be supported.

Adult↗

PubMed1997

Central venous stenosis in the hemodialysis patient: incidence and efficacy of endovascular treatment.

Central venous stenosis occurs as a complication of central venous catheterization and significantly complicates delivery of dialysis through arteriovenous grafts in the ipsilateral upper limb. This report includes two separate studies. Functioning expanded polytetrafluorethylene grafts have been prospectively evaluated using duplex scanning and angiography performed in all patients with stenoses > 50%. From this, it has been prospectively established that the incidence of unsuspected central venous stenoses in patients with functioning grafts is 29%. In the second part of the report, the authors' experience in the treatment of 25 central venous stenoses with percutaneous angioplasty and stent placement has been retrospectively reviewed. Initial technical success rate was 88%. Primary patency was 84% at 1 month, 42% at 6 months, and 17% at 1 year. Mean primary patency was 5.7 months. Stents were placed in five patients. Prevention of central venous stenosis by avoiding subclavian catheterization is optimal. Balloon angioplasty provides short-term patency, but it is the only option in most cases. The role for endovascular stent placement remains to be defined but early results are not optimistic.

Angioplasty, Balloon↗

PubMed1997

Oncogenesis of mammary glands, skin, and bones by polyomavirus correlates with viral persistence and prolonged genome replication potential.

A correlation between polyomavirus-induced oncogenesis and viral persistence on the one hand and/or prolonged genome replication potential on the other was established with respect to their respective organ distributions. Prolonged replication potential is defined as the capacity of a genome to replicate in a given organ from the time of infection up to the onset of oncogenesis. This conclusion was derived following intraperitoneal infection of BALB/c mice with wild-type strain A2. Viral genomes were used as parameters of persistence and replication and were detected by Southern blotting and PCR analysis. The major tumor target organs (mammary gland, skin, and bone), which have not been previously analyzed for persistence, were compared with other, non-tumor-prone organs (kidney, liver, lung, spleen, and salivary gland). A progressive loss of viral genomes was observed in all tissues as a function of time postinfection; however, genomes were shown to persist through 20 weeks postinfection in the mammary glands, skin, and bones to an extent similar to that in the previously described kidneys (D. J. McCance, J. Virol. 39:958-962, 1981; W. P. Rowe, J. W. Hartley, J. D. Estes, and R. J. Huebner, Natl. Cancer Inst. Monogr. 4:189-209, 1960). Thus, tumors arise among organs that sustain a persistent infection, but not all such organs develop tumors (e.g., the kidney). The capacity of organs to support de novo replication at various ages, including the age reached when the first tumors are detected, was also determined using a 3-day infection period for ages between 0 and 7 weeks. For all organs tested, a higher level of genomes was observed in organs of mice infected as neonates than in those infected after the age of 3 weeks. However, marked organ-specific differences were seen in the degree and timing of loss of replication. In particular, viral genome replication, although reduced, was maintained in the mammary glands, skin, and bones of adult animals, in contrast to the kidneys. We conclude that organ-specific oncogenesis correlates with two organ-specific parameters: persistence of viral genomes and prolonged viral genome replication potential. This may reflect a requirement for continued viral genome replication and/or gene expression for tumorigenesis. In turn, these parameters may be linked to the tissue-specific continued capacity for cellular division.

Animals↗

PubMed1996

Transjugular intrahepatic portosystemic shunt for the management of severe venoocclusive disease following bone marrow transplantation.

Hepatic venoocclusive disease (VOD) is a common, life-threatening complication of bone marrow transplantation (BMT). Portal hypertension is usually present and accounts for many of the clinical manifestations of this syndrome. We describe the results of transjugular intrahepatic portosystemic shunt (TIPS) for the management of VOD after BMT TIPS was performed in six patients with histologically confirmed VOD who had progressive jaundice and ascites. Portal hypertension was improved by TIPS in all patients (mean portal pressure gradient before TIPS, 20.2 +/- 4.6 vs. 6.7 +/- 1.9 mm Hg post-TIPS, P < .004). Three patients who underwent TIPS late in the course of VOD did not demonstrate any clinical improvement after TIPS and expired within 2 weeks of the procedure. The remaining three patients had less advanced disease and demonstrated decreases in serum bilirubin, improvement in coagulopathy, and decreased ascites after TIPS. Two patients subsequently expired, one with persistent histological changes of VOD. The lone survivor continues to do well with resolution of ascites, jaundice, and coagulopathy as of her last outpatient visit. TIPS was an effective method for portal decompression in patients with VOD after BMT, and was associated with clinical improvement in some patients. However, these effects may be transient and may not improve overall survival.

Adult↗

PubMed1995

Third degree atrioventricular block and acquired myasthenia gravis in four dogs.

Third degree atrioventricular block was diagnosed in 4 dogs with acquired myasthenia gravis (serum acetylcholine receptor antibody titer > 0.6 nmol/L). All 4 dogs had megaesophagus. Two dogs also had mediastinal thymomas, which were resected. One dog with thymoma received a permanent pacemaker at the same time that it underwent thymectomy; the other did not develop third degree atrioventricular block until 3 months after thymectomy. Both dogs with thymoma died of severe aspiration pneumonitis within 3 months after surgery. The third dog received a permanent pacemaker and was treated with pyridostigmine bromide, but also died of aspiration pneumonitis 1 month after the pacemaker was implanted. The fourth dog was treated with prednisolone and pyridostigmine bromide and improved, but did not become clinically normal. Because third degree atrioventricular block as well as myasthenia gravis can cause signs of weakness, acquired myasthenia gravis should be considered in dogs with idiopathic cardiac conduction disturbances. Likewise, an ECG should be evaluated in dogs with acquired myasthenia gravis.

Animals↗

PubMed1994

Hematologic emergencies.

The most common life-threatening hematologic emergencies include hemorrhage and severe anemia. Successful treatment of these conditions depends on the emergency veterinarian having a thorough understanding of the possible etiologies of these conditions, and a systematic approach to diagnosis and therapy. Use of blood component therapy can be a life-saving technique in these patients. The goal of this article is to familiarize the emergency veterinarian with a systematic approach to the diagnosis and treatment of hematologic emergencies.

Anemia↗

PubMed1994

Transjugular intrahepatic portal systemic shunt for the management of symptomatic cirrhotic hydrothorax.

OBJECTIVE: To investigate the safety and effectiveness of performing transjugular intrahepatic portal systemic shunt (TIPS) for the management of symptomatic cirrhotic hydrothorax in patients with advanced cirrhosis. METHODS: TIPS was performed by standard technique after portal vein patency had been established by ultrasound. Portal-hepatic vein pressure gradient was determined before and after placement of the shunt. A portal-hepatic vein gradient of less than 12 mm Hg was the treatment goal. RESULTS: Five patients underwent TIPS placement over an 11-month period. Despite use of diuretics, the patients had required a median of seven thoracenteses (range 2-11) for control of symptoms preceding placement of the shunt. A TIPS was placed without serious complications in all five patients. In two patients, insertion of the shunt was associated with no further need for thoracentesis. The other three patients had recurrent need for thoracentesis. These three patients were found to have occluded shunts which were rendered patent by angioplasty and/or urokinase. Subsequently, two required no further thoracentesis, whereas, in the other patient, the need for thoracentesis was decreased dramatically. CONCLUSIONS: TIPS appears to be a safe and useful technique for the management of patients with symptomatic cirrhotic hydrothorax that is refractory to medical therapy. Recurrence of the pleural effusion after placement of TIPS may be an indication of shunt occlusion.

Adult↗

PubMed1993

Local infusion of fibrinolytic agents for acute renal artery thromboembolism: report of ten cases.

Management of acute renal artery occlusion remains a therapeutic challenge. We report our experience with 10 cases of acute renal artery occlusion treated primarily by local infusion of fibrinolytic agents. Renal artery occlusion occurred as a result of thrombosis of a stenosed vessel in three cases, from renal artery embolism in two cases, as a complication of percutaneous transluminal angioplasty in four cases, and in association with aortic occlusion in one case. Flank pain was present in all cases and hematuria in four cases. Acute renal failure was seen at the time of presentation in four cases (one case from bilateral occlusion and three cases from an associated nonfunctioning contralateral kidney). Diagnosis was confirmed by renal isotope scanning and arteriography in all cases. All patients were treated by selective infusion of streptokinase or urokinase into the occluded renal arteries. In five cases this was combined with balloon catheter angioplasty. Therapy was initiated within 24 hours from the onset of symptoms in three cases, within 3 days in four cases, within 6 days in two cases, and after 5 weeks in one case. Successful revascularization was initially achieved in 7 of the 10 cases by arteriographic criteria. Rethrombosis occurred in one patient after 3 days and fibrinolytic therapy was repeated successfully. Renal function was restored in one of the four patients presenting with acute renal failure. One complication necessitating resection occurred as a result of fibrinolytic therapy in the form of acute mesenteric embolism with descending colon infarction. No major bleeding complications were encountered and there were no deaths in this group of patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗

PubMed1993

Effects of sex steroids on myocardial anoxic resistance.

Eight treatment groups of CD strain castrate male or female rats were injected daily with cottonseed oil (sham), testosterone propionate (50 micrograms/100 g body wt), estradiol benzoate (7 micrograms/100 g body wt), or a combination of both steroids dissolved in cottonseed oil. These physiologic replacement dosages of sex steroids, determined by bioassay procedures, were injected in a 0.1-ml bolus of cottonseed oil daily (intraperitoneally) for 16 weeks. Myocardial anoxic resistance was quantified by means of an in vitro right ventricular strip preparation that evaluated the ability of the isolated right ventricle to maintain contractions in response to electrical pacing at 1 Hz after 10 min of anoxia. While this parameter was elevated 2- to 3-fold in the estrogen-treated groups of male and female castrates compared with the sham (oil)-injected groups, neither testosterone treatment alone nor combination steroid treatment produced anoxic resistance values that differed significantly from those of the sham-injected animals. Thus, although estrogen alone may afford anoxic protection to the myocardium, testosterone is able to abolish this hormone-induced protection.

Analysis of Variance↗

PubMed1993

Polytetrafluoroethylene aorta-vena cava graft for hemodialysis: report of a case.

In children with chronic renal failure, vascular access for hemodialysis is difficult because of the small size of the vessels and the requirement for substantial blood flow through the fistula or graft. As the child grows older, the ease of constructing a satisfactory access usually increases as the vessels increase in size. Unfortunately, this increased ease is often offset by the paucity of suitable access sites because the larger peripheral sites have already been used with only transient success. We report a child with chronic renal failure since 1 month of age with no peripheral sites available because of prior failed procedures who underwent placement of polytetrafluoroethylene limbs to the aorta and vena cava at the age of 6 years. He has continued on hemodialysis for the past 4 1/2 years with this technique of vascular access.

Animals↗

PubMed1992

Nonoperative management of visceral aneurysms and pseudoaneurysms.

During the period from 1975 to 1991, 41 patients with 60 visceral artery aneurysms were treated at the Affiliated Hospitals of Emory University. The total included 13 patients in whom 16 aneurysms were treated primarily by transarterial embolization. There were seven hepatic artery aneurysms, three splenic artery aneurysms, three gastroduodenal artery aneurysms, two left gastric artery aneurysms, and one right gastroepiploic artery aneurysm. Average age of these patients was 50 years; there were eight males and five females. Seven patients presented with gastrointestinal bleeding, and two patients presented with abdominal pain. In four patients, the aneurysm was an incidental finding. Etiology of the true or false aneurysms consisted of pancreatitis in two patients, trauma in three patients, connective tissue disease in one, and was unknown in the remainder. Embolization was performed in seven cases with Gianturco coils and Gelfoam, with coils alone in four, with Gelfoam alone in four, and with detachable balloons in one instance. Complete occlusion was achieved initially in 13 cases. Recanalization occurred in two patients over a mean follow-up period of 8.6 months, requiring re-embolization in one patient, whereas the other patient was managed expectantly. In three cases, embolization was unsuccessful: two cases required surgical correction, and one case was managed expectantly. Only one complication was related to the embolization procedure, which was a common hepatic arterial dissection that proceeded to the formation of a false aneurysm. Embolization as the primary treatment modality for visceral artery aneurysms should be considered in patients with the following diagnoses: pseudoaneurysms associated with pancreatitis, intrahepatic aneurysms, most splenic artery aneurysms, and gastric, gastroduodenal, and gastroepiploic aneurysms. The procedure has a low risk and may obviate a difficult surgical procedure, but it does not preclude surgical intervention should the need arise.

Adolescent↗

PubMed1992

Long-term results of angioplasty in 110 patients with renal artery stenosis.

Percutaneous transluminal renal angioplasty (PTRA) is generally considered of little benefit in the treatment of ostial renal artery stenosis. This report contains long-term follow-up (> 12 months in all patients; mean follow-up, 38 months) for 110 patients who underwent PTRA for treatment of ostial renal artery stenosis. There was no significant difference in patient benefit related to bilaterality or multiplicity of lesions treated or to renal function before angioplasty (P > .1). Although there was no statistically significant difference in benefit among groups of patients who received treatment, certain trends were apparent. The least benefit occurred in patients with insulin-dependent diabetes and those with symptoms or history of vascular disease in another organ system. Treatment of lesions with proportionately larger balloons did not result in greater benefit. Restenoses were redilated in 16 patients for whom initial treatment failed. Eleven of these were ostial restenoses. The ostial stenosis in one patient was redilated a second time. At the end of follow-up, primary, secondary, and tertiary clinical benefits were 48%, 57%, and 58%, respectively. This was not statistically different (P = .14) from a control group of 94 patients with nonostial stenoses who had 68% long-term benefit. The authors conclude that ostial renal artery stenosis is not a contraindication to PTRA, and balloon angioplasty can play an important role in blood pressure control in this patient population.

Adult↗

PubMed1992

Living arrangements of elderly Japanese and attitudes toward inheritance.

Using data from the 1988 Mainichi Newspaper/Nihon University National Family Survey, we analyzed the living arrangements and attitudes toward inheritance of Japanese aged 60 and over. Logit analysis indicates that living arrangements are influenced by gender, age, marital status, education, urban residence, and number of living children. Log-linear modeling of inheritance attitudes shows that living with married children, lower educational attainment, and living in a traditionally agricultural area are associated with favoring bequests to eldest sons, as opposed to bequests to all children equally or to whoever takes care of the elderly person. The results are consistent with modernization theory of gerontology and convergence theory of family sociology in that elderly persons with more "modern" characteristics are more likely to depart from prewar ideals of living with married children and preferring bequests to eldest sons only.

Aged↗