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Biomedical subjects

C Gross

Publications and source records attributed to C Gross.

At least 109 records · Page 6Linked to original sources
PubMed1995

Aortic valve replacement: is the stentless xenograft an alternative to the homograft? Early results of a randomized study.

From November 1992 to October 1993 we randomized 101 patients over 60 years of age undergoing elective aortic valve replacement, with or without concomitant coronary artery bypass grafting, to receive either a cryopreserved aortic or pulmonary homograft (n = 38) or a stentless porcine aortic valve xenograft (Edwards Prima 2500) (n = 63). The majority of all valves (92%) were inserted freehand in the subcoronary position. Six homografts (16%) were implanted as a free-root replacement and two xenografts (3%) were used as a mini root. There were four in-hospital deaths (4%), three in the homograft group and one in the xenograft group (homograft, 7.9% versus xenograft, 1.6%; p = not significant). Forty-one patients were followed at 3- to 6-month intervals for 9 +/- 2 months (3 to 14 months) and valve pathology was assessed routinely by means of color flow Doppler echocardiography. Two patients in the homograft group developed new aortic insufficiency grade II; all others remained with trivial or no valve incompetence. The mean gradient remained unchanged to immediate postoperative measurements (homograft, 5 +/- 1 mm Hg versus xenograft, 11 +/- 4 mm Hg; p < 0.001). Despite a slightly higher transvalvular gradient, xenografts achieved excellent initial results when compared to homografts. Ease of implantation and freedom from thromboembolism indicate that xenografts can be an acceptable alternative to homografts, particularly in older patients with small aortic annuli. Long-term studies assessing the durability of the xenograft are necessary for final evaluation.

Aged↗
PubMed1995

Aortic valve replacement with cryopreserved pulmonary allografts: five years' follow-up.

Excellent clinical results with pulmonary autografts and experimental evidence that pulmonary valves can withstand the higher stress in the systemic circulation led us to use the cryopreserved pulmonary allograft for aortic valve replacement. From September 1988 until March 1993, 126 consecutive patients (61 +/- 10 years; 74 men and 52 women) underwent aortic valve replacement with a cryopreserved pulmonary allograft. All allografts were inserted freehand in the subcoronary position. There were four in-hospital deaths (3.2%), and 1 patient had severe valvular incompetence immediately postoperatively, requiring reoperation after 4 weeks. One hundred twenty-one patients were followed up in 3- to 6-month intervals for 25.3 +/- 16.3 months (range, 6 to 66 months), and valve performance was assessed routinely by means of color-flow Doppler echocardiography. Nine patients (7.1%) died during follow-up. Two patients died of multiple septic emboli during bacterial endocarditis, and 1 patient died of a massive stroke. The other 6 patients died of myocardial infarction (4), respiratory insufficiency due to chronic obstructive lung disease (1), and carcinoma (1). Ninety-four patients (78%) had absent or trivial aortic valve regurgitation. Valvular incompetence class II was present in 3 patients (2.5%), whereas 5 others (4%) demonstrated class II to III. Severe aortic regurgitation (class III or IV) could be detected in 10 patients (8.3%). All underwent reoperation and replacement of the valve with a prosthetic device. Bacterial endocarditis caused graft incompetence in 3 patients, valve degeneration was detected in another 3, and technical mistakes at valve implantation caused valve failure in the other 4.(ABSTRACT TRUNCATED AT 250 WORDS)

Actuarial Analysis↗
PubMed1995

Skin blood flow measurements on the breast areola.

Blood flow and thermally insulated skin temperature were measured in the aerolae of normal breasts by means of the non-invasive transient thermal clearance method. Both parameters showed high variability among different women, but also showed typical dependence on the subject's age: the two parameters were constant up to age 50, and then showed a decrease at higher ages. The decrease can be attributed to the normal decrease of tissue blood flow at higher age and to atrophy of the breast glandular tissue after menopause. Statistically significant higher values of blood flow and insulated skin temperature were found for the left breast relative to the right breast.

Adult↗
PubMed1995

Lysolecithin-induced demyelination in primates: preliminary in vivo study with MR and magnetization transfer.

PURPOSE: To study bystander demyelination in multiple sclerosis with an experimental in vivo model of toxic demyelination. METHODS: Toxic demyelinating lesions were created in two monkeys by injection of lysophosphatidylcholine in the centrum semiovale. Follow-up was done clinically and with serial MR studies, including T2-weighted and gadolinium-enhanced T1-weighted images and measurement of magnetization transfer ratio, until the animals were killed at days 14 and 34, respectively. Light and electron microscopy analysis was compared with MR data. RESULTS: Interval measurement of magnetization transfer ratio during the course of the experiment revealed a maximum decrease at day 7 to day 8, associated with the greatest clinical manifestations. The lowest values of magnetization transfer ratio correlated with histopathologic findings of myelin and axon destruction. Magnetization transfer ratio measurements appear to be sensitive to macromolecular destruction and specifically to membrane disorganization. At no time was gadolinium enhancement observed in this model of toxic demyelination. CONCLUSION: Preliminary results of this study indicated that magnetization transfer is a good technique to follow in vivo matrix destruction in brain parenchyma lesions. The results suggest also that phases of toxic demyelination in multiple sclerosis might not show gadolinium enhancement. Differentiation between demyelinating activity and associated inflammation in multiple sclerosis lesions should be considered in further in vivo work.

Animals↗
PubMed1995

[Heart surgery in the elderly].

The number of octogenarian patients undergoing an open heart procedure in our unit is the fastest increasing group of patients. Between June 1985 and July 1994 112 octogenarians (mean age 81.7 years, 60 males, 52 females) underwent cardiac operations. The postoperative course was uneventful in 90 patients (80.4%). The perioperative mortality rate was 8.9% (10 patients). Mortality was lowest in the group receiving aortic valve replacement, with one death out of 30 patients (3.3%). The cause of death was left- or biventricular heart failure in more than half of the fatalities. Postoperative complications included: AV-block III (n = 1), postoperative bleeding (n = 2), unstable sternum (n = 3), acute cholecystitis (n = 1), low cardiac output syndrome (n = 1), stroke (n = 1), pneumothorax (n = 2) and urinary tract infections (n = 1). We consider open heart procedures in octogenarians, despite a mortality rate of 8.9%, as justified. According to the severity and course of clinical symptoms and the type of surgery required, selection of patients for operation should be decided on at an early stage of the disease. Not only life expectancy increases, but there is also a significant increase in life quality for these patients.

Aged↗
PubMed1994

Determination of intrinsic transcription termination efficiency by RNA polymerase elongation rate.

Transcription terminators recognized by several RNA polymerases include a DNA segment encoding uridine-rich RNA and, for bacterial RNA polymerase, a hairpin loop located immediately upstream. Here, mutationally altered Escherichia coli RNA polymerase enzymes that have different termination efficiencies were used to show that the extent of transcription through the uridine-rich encoding segment is controlled by the substrate concentration of nucleoside triphosphate. This result implies that the rate of elongation determines the probability of transcript release. Moreover, the position of release sites suggests an important spatial relation between the RNA hairpin and the boundary of the terminator.

Base Sequence↗
PubMed1994

[Use of autologous femoral vein in superior vena cava thrombosis. Case report and review of the literature].

We report on a 52-year old male patient who underwent implantation of an insulin pump because he had diabetes and in whom superior vena cava syndrome developed as a long-term complication. After unsuccessful lysis therapy superficial femoral vein was implanted to form a bypass from the internal jugular vein to the right atrium. The postoperative course was uneventful from the aspects of both the bypass and the leg after explantation of the superficial femoral vein. The bypass is still patent 7 months after the operation, and the patient has no symptoms. Autogenous superficial femoral vein can be used successfully in the reconstruction of large venous vessels. It should be the graft of choice for young patients with benign diseases. We compare our result and those obtained with different substitutes described in the literature that have been used for reconstruction in superior vena cava syndrome.

Femoral Vein↗
PubMed1994

Mycotic aneurysms of the thoracic aorta.

Between February 1982 and December 1992 we operated on five patients (three men, two women; aged 40 to 70 years) with mycotic aneurysms of the thoracic aorta. One patient had an aneurysm of the ascending aorta, once the aortic arch and in three cases the descending thoracic aorta were involved. In four of the five patients, excision of the aneurysm and in situ reconstruction of the aorta with a Dacron graft was performed, one patient required a Dacron graft repair and aortic valve replacement. We employed deep hypothermia with circulatory arrest (2), extracorporeal circulation (1), an axillofemoral shunt (1) and a centrifugal pump (1) for cerebral and spinal cord protection. One patient died 4 months postoperatively, the other four patients were without recurrent graft infection and are free of symptoms between 20 months and 5 years postoperatively.

Adult↗
PubMed1994

The octogenarians--a new challenge in cardiac surgery?

The per- and early postoperative outcomes of 75 consecutive octogenarians (38 male, 37 female, mean age 81.7 years) who underwent open heart surgery were analysed to identify independent variables of risk factors influencing morbidity and mortality. There were 48 coronary bypasses. 20 valve replacements, and 7 combined procedures. Multivariate analysis revealed that functional class (New York Heart Association), operative procedure, aortic cross clamp time, total bypass time, and age are independent predictors for morbidity and mortality (p < 0.05). There were 6 postoperative deaths (8%). Postoperative complications included haemorrhage (2), stroke (1), unstable sternum (2), acute cholecystitis (1), pneumothorax (2), and urinary tract infection. It is concluded that octogenarians may benefit from open heart surgery at an acceptable risk.

Aged↗
PubMed1994

Acute and long-term effects of subthalamic nucleus stimulation in Parkinson's disease.

In animal models of Parkinson's disease (PD), it is postulated that the excessive output from the subthalamic nucleus (STN) plays a critical role. Selective lesions or high frequency electrical stimulation of the STN can alleviate parkinsonian symptoms in MPTP-treated monkeys. We decided to carry out STN stimulation in patients suffering from severe akinetic forms of PD. After approval of the institutional ethical committee, we operated on a parkinsonian patient aged 51, suffering for 8 years from a strongly disabling akinetorigid form of PD, complicated by an on-off effect (Hoehn and Yahr stage 5 in the worst-off motor phase). Stereotactic surgery was done on one side under local anesthesia. The theoretical target was chosen according to stereotactic atlases, based on ventriculographic landmarks such as anterior and posterior commissures (AC and PC). The final position of the chronic electrodes was optimized using electrophysiological recording and stimulation along with clinical assessment and surface EMG of agonist and antagonist muscles of the examined limbs. A spontaneous increase in neuronal activity was recorded in an area located 2-4 mm under the level of the intercommissural plane, 10 mm from the midline, at mid-distance between AC and PC. Within the same place, a 130-Hz stimulation induced acute and reversible akinesia alleviation mainly on the contralateral limbs, comparable to that obtained with dopaminergic drugs. No dyskinesia, such as hemiballism, was induced by introduction of electrodes or by stimulation. Then a long-term quadripolar DBS Medtronic electrode was inserted in this area. Studies of the effects of chronic stimulation were extensively performed to determine the best spatiotemporal and electrical stimulation variables.(ABSTRACT TRUNCATED AT 250 WORDS)

Electric Stimulation Therapy↗
PubMed1994

Coronary disease and tracheal stenosis with tracheo-oesophageal fistula: a combined surgical procedure.

A patient with coronary disease class III of the New York Heart Association and tracheal stenosis with a tracheo-oesophageal fistula, which developed after long-term intubation, is described. As both conditions were symptomatic, an aortocoronary double bypass was combined with resection of the trachea and closure of the fistula. Postoperative recovery was uneventful and the patient is symptom-free after 3 years.

Adult↗
PubMed1993

Reversal of rigidity and improvement in motor performance by subthalamic high-frequency stimulation in MPTP-treated monkeys.

In Parkinson's disease the loss of dopaminergic neurons in the substantia nigra is associated with global disorganization of basal ganglia activity and, in particular, with increased activity of the excitatory glutamatergic neurons of the subthalamic nucleus. Recent experimental studies have shown that parkinsonian symptoms can be alleviated by selective lesioning of the subthalamic nucleus in monkeys treated with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). We measured the effect of high-frequency stimulation of the subthalamic nucleus in two unilaterally MPTP-treated monkeys in order to determine whether it was possible to obtain reversible, gradual and controllable functional impairment of this structure. Clinical, mechanographic and electromyographic results demonstrate that this technique can alleviate parkinsonian rigidity and bradykinesia without causing dyskinesia or hemiballismus. This study supports the hypothesis that the subthalamic nucleus and its excitatory projections have an important role in the mechanisms sustaining the expression of parkinsonian motor changes, and suggests that high-frequency stimulation of the subthalamic nucleus could be included in treatment for parkinsonism.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗
PubMed1993

Effects of nimodipine on posttraumatic spinal cord ischemia in baboons.

Posttraumatic ischemia appears to be largely responsible for the extension of lesions in acute injury of the spinal cord. In the present study, we have evaluated the putative improvement of axonal function by the calcium channel blocker nimodipine after acute trauma of the spinal cord. Three techniques were used: (1) spinal cord blood flow (SCBF) using a scanographic technique with stable xenon, (2) somatosensory evoked potentials (SEPs), and (3) magnetic resonance imaging (MRI). Thirteen baboons were used in this study. Acute trauma was achieved by compression of the spinal cord at level L1 by applying pressure for 5 sec with an inflated balloon catheter injected with Ringer's solution. Following the injury, one group (n = 5) received a saline infusion (placebo) for seven days, and a second group (n = 8) received a nimodipine infusion (0.04 mg/kg/h) during the same period of time. SCBF and SEP were first recorded prior to trauma. SCBF, SEPs, and MRI were then recorded on the day of the injury and eight days prior to histologic examination of the spinal cord. In these studies nimodipine significantly improved SCBF. The decrease in SCBF observed at day one and day eight following trauma was significantly reduced in the treated group. Two baboons in the treated group also showed improvement of axonal function as assessed by SEP. No significant difference was observed with MRI, however, histologic study revealed that the lesions were significantly smaller in the treated group. Based on these observations we conclude that a week of nimodipine treatment following spinal cord injury enhances SCBF, limits the size of the spinal cord lesion, and perhaps improves functional recovery.

Animals↗
PubMed1993

Presence of a specific antiestrogen binding site on human follicular thyroid carcinoma cell line (UCLA RO 82 W-1): inhibition by an endogenous ligand present in human serum.

A receptor for antiestrogens, distinct from the estrogen receptor, has been identified in several tissues including the MCF-7 breast cancer cell line. Estrogen receptors have also been found in normal and pathological thyroid tissue homogenates. We demonstrate the presence of an antiestrogen binding site (AEBS) on a pure human follicular thyroid carcinoma cell line (UCLA RO 82 W-1) using a 3H-tamoxifen (3H-TAM) binding assay. The binding of 3H-TAM to the AEBS was determined after preincubation (30 min) of the cells with excess 17 beta-estradiol (2 mumol/L). Specific and saturable binding of 3H-TAM to the cells was observed. Displacement of the tracer from its binding site was dose dependent. Scatchard analysis revealed a dissociation constant (Kd) of 73 nmol/L, indicating a binding site with moderate affinity and capacity (72 pmol/10(6) cells). Using this assay we were also able to demonstrate the presence of an endogenous ligand for the AEBS in ethanol extracts of human serum. Cell growth and 3H-thymidine incorporation by the follicular thyroid carcinoma cells were inhibited when the cells were exposed to TAM (1.5 mumol/L). In conclusion, TAM is able to bind to a specific receptor on this follicular thyroid carcinoma cell line, and a natural circulating ligand present in ethanol extracts of human serum interferes with its binding.

Adenocarcinoma, Follicular↗
PubMed1993

Cardiac angiosarcoma--a diagnostic dilemma.

A 25-year-old man suffering from sudden onset of haemoptysis after 1 week of orthopnoea, fatigue and general weakness was admitted to a cardiology department in Vienna. No diagnosis was made. Four weeks later cardiopulmonary resuscitation and pericardiocentesis were necessary because of cardiac tamponade. Although all modern imaging procedures were performed, a diagnosis of rapidly progressive primary cardiac angiosarcoma could not be established. Definitive diagnosis was established only after exploratory median sternotomy. The patient exhibited no response to chemotherapy. He died 5 days after surgery as a result of respiratory failure.

Adult↗