Light and electron microscopic studies of phrenic nerves after long-term electrical stimulation

Light and electron microscopic evaluation were carried out on canine phrenic nerves subjected to long-term electrical stimulation. A total of 34 stimulated and 19 control nerves were studied by light microscopy, and 10 stimulated and five control nerves were evaluated by electron microscopy. Except in a few cases in which a higher current was used, the current used for stimulation was between 1 and 2 mA. The pulse width was 150 microseconds. The typical charge per pulse was 0.22 microC and charge density per pulse 1.125 microC/sq cm of real area. The total number of days of electrical stimulation in individual phrenic nerves ranged from 4 to 374. No morphological changes in the phrenic nerve that could be attributed to the electrical stimulation were observed by light or electron microscopic study. There were, however, two phrenic nerves cuffed with bipolar electrodes which showed focal demyelination at the electrode level, but these changes were caused by factors other than the electrical stimulation. The results of the studies have direct clinical implications to long-term stimulation of phrenic nerves.

Ultrastructural findings in experimental Creutzfeldt-Jakob disease in guinea pigs

Brains from six clinically ill guinea pigs from various serial passages infected with brain homogenate from a patient with Creutzfeldt-Jakob disease were studied by light and electron microscopy. There were no appreciable morphologic differences among the animals at different passages. Light microscopy revealed clearing, swelling, and vacuolar changes in neurons and astrocytes. These changes occurred in both perikarya and cell processes. Large isolated vacuoles in the neuropil appeared to develop by progressive fusion between swollen cellular processes. By electron microscopy many neuronal processes contained degenerating organelles, osmiophilic bodies, membranous bodies and approximately 10 mm filamentous structures. In addition, vacuoles and membranous inclusions were seen in some neuronal nuclei, changes which have not been previously observed in spongiform encephalopathies.

Radiation induced sarcomas of bone following therapeutic radiation

Because of new therapeutic trends of multi-modality and the importance of late effects, we have updated our series of radiation induced bone sarcomas seen at Memorial Sloan-Kettering Cancer Center over the past four decades. A total of 37 cases of bone sarcoma arising from normal bone in the irradiated field was analyzed. The median for latent period from irradiation to diagnosis of bone sarcoma was 11 years with a minimum latent period of four years. The median radiation dose for the bone sarcoma was 6000 rad in 6 weeks with a minimum total radiation dose of 3000 rad in 3 weeks. We have found nine patients who developed bone sarcomas in the radiation field after successful treatment of Hodgkin's disease. Criteria for radiation induced bone sarcomas and the magnitude of the risk of bone sarcomas are briefly discussed.

Combination hyperthermia and radiation therapy for malignant melanoma

Since 1975, clinical studies have been carried out to determine whether radiation when combined with localized hyperthermia evokes improved tumor control compared to that achieved with radiation alone. Local tumor hyperthermia was achieved using radiofrequency inductive heating at 27.12 MHz. In bulky lesions (greater than 100 cm3), radiofrequency conductive heating at 13.56 MHz was also used. More than 100 lesions in 38 patients were treated with radiation alone and hyperthermia in combination with radiation. Most lesions were treated either twice a week or once a week, depending on radiation dose fractionation scheme used. The overall result of tumor control rate of the combined therapy is superior to radiation therapy alone (75% versus 46%; P less than 0.01). No enhanced normal tissue morbidity was seen following the combined therapy. The detailed analysis of the treatment results shows that the tumor control rate is dependent on dose per fraction, the total dose, and the initial tumor volume. The radiation alone, at high doses per fraction, was effective in controlling 80% of the lesions, if the tumor volume was less than 10 cm3, compared to 30% when the tumor volumes were larger. The combination therapy, on the other hand, effected 80% local tumor control regardless of the tumor volume. The importance of good thermal distribution within the tumor volume, selective heating of the tumor tissues and the sequence and time interval between the combined therapy is discussed.

Preliminary trial of combination therapy with adriamycin and radiation in sarcomas and other malignant tumors

Based on reports of synergism between adriamycin and radiation therapy in experimental systems, a trial was initiated testing this combination in 53 adult patients with various advanced malignancies, especially sarcomas. Since studies have suggested as selective sensitization of hypoxic cells when this drug is given prior to radiation, an injection of low-dose adriamycin was given 90 min before radiation. This treatment was repeated every 7 days. The combination was most effective in the 30 patients with soft-tissue sarcomas, with 62% of these patients having partial or complete responses. Responses were less good in patients with gastric adenocarcinoma or with other tumors. The toxicity of the combined treatment was moderate. Further trials of this combination are warranted.

Combination hyperthermia and radiation therapy for malignant melanoma

Since 1975, clinical studies have been carried out to determine whether radiation when combined with localized hyperthermia evokes improved tumor control compared to that achieved with radiation alone. Local tumor hyperthermia was achieved using radiofrequency inductive heating at 27.12 MHz. In bulky lesions (greater than 100 cm3), radiofrequency conductive heating at 13.56 MHz was also used. More than 100 lesions in 38 patients were treated with radiation alone and hyperthermia in combination with radiation. Most lesions were treated either twice a week or once a week, depending on radiation dose fractionation scheme used. The overall result of tumor control rate of the combined therapy is superior to radiation therapy alone (75% versus 46%; P less than 0.01). No enhanced normal tissue morbidity was seen following the combined therapy. The detailed analysis of the treatment results shows that the tumor control rate is dependent on dose per fraction, the total dose, and the initial tumor volume. The radiation alone, at high doses per fraction, was effective in controlling 80% of the lesions, if the tumor volume was less than 10 cm3, compared to 30% when the tumor volumes were larger. The combination therapy, on the other hand, effected 80% local tumor control regardless of the tumor volume. The importance of good thermal distribution within the tumor volume, selective heating of the tumor tissues and the sequence and time interval between the combined therapy is discussed.

Radiofrequency hyperthermia for clinical cancer therapy

Radiofrequency heating by the inductive or capacitive mode has the potential to induce hyperthermia at depth. Progress with the capacitive heating with the use of multiportal electrodes and impedance matching showed promise for improved depth of heating. However, heating of the fatty tissue remains a major obstacle. The inductive modality has been widely used for diathermy, and a modified unit is being used for treatment of superficial tumors. The inductive mode has great promise for heating deep-seated tumors because it is least affected by the tissue inhomogeneities. With radiofrequency heating, temperature measurements between the tumor and the adjacent normal tissue almost always showed a selective heating pattern. Tumor response to the heat alone has been transitory; however, permanent control can be achieved in over 75% when combined with irradiation without an increase in normal tissue complications.

Effects of alpha-adrenoceptor antagonists administered intraventricularly on central hypotensive action of clonidine and on central hypertensive action of methoxamine in rabbits

In urethane-anesthetized rabbits blood pressure was lowered by intraventricular clonidine (30 microgram) and increased by intraventricular methoxamine (1 mg). Clonidine is well known to cause hypotension by acting on central alpha-adrenoceptors. The hypertensive effect of intraventricular methoxamine was not observed in cord-sectioned rabbits, in guanethidine-treated adrenalectomized rabbits and in phentolamine-treated rabbits, indicating the effect was central in origin. These responses to intraventricularly administered clonidine and methoxamine were examined in rabbits pretreated intraventricularly with various alpha-adrenoceptor antagonists believed to exhibit preference for alpha 1- or alpha 2-adrenoceptors in the peripheral tissues. Pretreatment with 250 microgram of yohimbine and with 500 microgram of piperoxan inhibited the clonidine hypotension, but pretreatment even with 2 mg of either of these drugs did not affect the methoxamine hypertension. In contrast, pretreatment with 8 microgram of prazosin inhibited the methoxamine effect, whereas pretreatment even with 1 mg of prazosin did not affect the clonidine effect. Pretreatment with 8 microgram of thymoxamine inhibited the methoxamine effect, while it was necessary to increase the doses for each drug up to 4 to 8 times to oppose the clonidine effect. Pretreatment with 2 mg of labetalol inhibited the methoxamine effect but was ineffective against clonidine. Pretreatment with 500 microgram of phentolamine was effective in antagonizing the clonidine effect but twice the dose was needed to inhibit the methoxamine effect. From the findings that the hypertensive effect of methoxamine and the hypotensive effect of clonidine were inhibited differently by various alpha-adrenoceptor antagonists and that the selectivity of these antagonists for the methoxamine and clonidine effect is similar, respectively, to that for alpha 1- and alpha 2-adrenoceptors in the peripheral tissues, we concluded that the methoxamine hypertension and the clonidine hypotension are due to the stimulation of alpha 1- and alpha 2- adrenoceptors in the brain, respectively.

The effects of hyperthermia on fast axoplasmic transport in rat sensory fibers

The fast axoplasmic transport rate increased exponentially with the temperature from 30-45 degrees C. No decline in the fast axoplasmic transport rate was detected during hyperthermic conditions. Hyperthermic conditions induced a decrease in the amplitude of the advancing crest as well as a decline in the slope of the leading edge of the advancing wave in the sciatic nerve. This may suggest that there is a decline in the number of viable fibers transporting the material in these hyperthermic conditions.

Studies in semi-admissible heuristics

The paper introduces three extensions of the A* search algorithm which improve the search efficiency by relaxing the admissibility condition. 1) A* employs an admissible heuristic function but invokes quicker termination conditions while still guaranteeing that the cost of the solution found will not exceed the optimal cost by a factor greater than 1 + . 2) R¿* may employ heuristic functions which occasionally violate the admissibility condition, but guarantees that at termination the risk of missing the opportunity for further cost reduction is at most ¿. 3) R¿*,* is a speedup version of R¿*, combining the termination condition of A* with the risk-admissibility condition of R¿*. The Traveling Salesman problem was used as a test vehicle to examine the performances of the algorithms A* and R¿*. The advantages of A* are shown to be significant in difficult problems, i.e., problems requiring a large number of expansions due to the presence of many subtours of roughly equal costs. The use of R¿* is shown to produce a 4:1 reduction in search time with only a minor increase in final solution cost.

Role of cell-mediated immunity in tumor eradication by hyperthermia

A single hyperthermic treatment (44.5 degrees for 20 min) which results in successful local control of a 7-day intradermally growing fibrosarcoma in intact mice fails to permanently control tumor growth in immunodeficient nu/nu (BALB/c) or immunosuppressed (whole-body radiation, 500 rads) mice. Studies were designed to determine whether humoral or cellular-mediated factors were responsible. Nude mice were reconstituted with either heterozygotic (nu/+) sensitized or nonsensitized splenic T-cells. Similarly, semisyngeneic immunosuppressed BALB/c x C57BL/6 F1 hybrids were reconstituted with homologous sensitized and nonsensitized T-cells or sera prior to hyperthermic treatment of a 7-day intradermal Meth-A implant. Successful local tumor control by hyperthermia was effected in those animals reconstituted with greater than or equal to 1.8 x 10(7) splenic T-cells but not in those with sera. The inhibition of macrophage activity (chronic silica, i.p.) could substitute for whole-body radiation immunosuppression. These studies indicate that a thermally induced tumor cure would appear to be mediated by an activated macrophage-antigen-T-cell interaction which may be dependent on the initial expression of cell-mediated antitumor immunity that may be generated only in response to immunogenic tumors.

Effectiveness of once weekly total skin electron beam therapy in mycosis fungoides and Sezary syndrome

During the past eight years, 137 patients with mycosis fungoides were given total skin electron beam therapy (TSEB) using 2.5 to 4 MeV electrons. A single treatment delivers 400 rads to the entire skin surface, and patients are treated once a week for six to eight consecutive weeks. All have been followed for a median of 18 months (range 6-103 months). Although approximately 80 to 90% of the total population were in the advanced stages of the disease and had been previously treated elsewhere, cutaneous lesions and associated symptoms were effectively controlled. The remission lasted 6 to 103 months (median 19 months) after beginning the therapy for 109 mycosis fungoides patients, who were at risk for 12-103 months (median 24 months). Erythroderma and circulating Sezary cells adversely affected the duration of remission and indicate extracutaneous dissemination. Lymphocyte responsiveness to various mitogens and antigens correlated well with duration of the remission that was obtained from a course of TSEB.

Cutis marmorata telangiectatica with multiple congenital anomalies (van Lohuizen's syndrome)

A 5-year-old Korean boy with diagnosis of cutis marmorata telangiectatica congenita had a bluish-red, widespread livedo network over the entire body surface. There was skin atrophy as well as ulceration and crust over some of the lesions. These abnormalities have been associated with mental retardation with abnormal EEG findings, speech disability, defective growth, cleft palate, presence of simian lines and an increase in the atd angles of both palms, diffuse demineralization of bony structure and weakness of the long extensor muscles of both thumbs. Based on our clinical datas and review of world literature, it would seem to be necessary to change the terminology.

Epidural spinal cord compression from metastatic tumor: results with a new treatment protocol

Eighty-three patients with epidural spinal cord compression, from metastatic cancer were treated with high-dose adrenocorticosteroids and a new radiation fractionation protocol. Only those patients were included who had complete or almost complete block on myelography and who had not received prior radiation therapy to the area of compression. Patients were given 100 mg of dexamethasone intravenously at the time of diagnosis and 500 rads of radiation on each of the first three days. After a four-day rest, radiation therapy was continued at 300 rads to a total dose of 3,000 rads. The effects of this new protocol on the patient's motor abilities did not differ from those of previous protocols, namely, 47 of 83 patients (57%) were ambulatory after treatment, with no responses in patients totally paraplegic before treatment. However, early administration of high doses of dexamethasone substantially ameliorated pain in the majority of patients, with relief often coming within hours after the drug was given. On the basis of these data, we recommend high doses of adrenocorticosteroids combined with radiation therapy for acute treatment of spinal cord compression. The optimum fractionation schedule for radiation therapy is not established.

Selective killing of glucose and oxygen-deprived HeLa cells by hyperthermia

We previously have reported that glucose deprivation specifically enhance cell killing by hyperthermia in the absence of oxygen. The present studies were carried out to evaluate the interplay of glucose and oxygen on cell killing by hyperthermia (37 to 42 degrees) for up to 4 hr under varying concentrations of glucose (0 to 1 mg/ml) and oxygen (0 to 21%). pH 7.4 was maintained in all trials. In the absence of oxygen, enhanced cell killing at 40 and 42 degrees was seen with glucose concentrations below 0.1 and 0.25 mg/ml of media, respectively. In the absence of glucose, enhanced killing was seen when oxygen concentrations were below 1 and 2% at 40 and 42 degrees, respectively. The radiosensitivity of the cells was influenced only by the oxygen concentration during irradiation and not by glucose. These results indicate that oxygen and glucose are important modifying factors of cell lethality by hyperthermia.

Progressive white matter destruction following irradiation of an extracranial neoplasm

Although numerous "cures# have been reported following surgical extirpation of symptomatic foci of cerebral radiation nerosis, delayed progressive white matter destruction and neurological deterioration may occur in some patients who survive for prolonged periods after operation. The postoperative appearance on CT scans of hypodensity within heavily irradiated white matter structures at a distance from the initial radionecrotic focus or operative site suggests continuing radiation-induced tissue injury and a poor prognosis. Anticipated survival as well as administered radiation dose must be taken into account when "safe# radiation thresholds are calculated.

Radiation therapy for brain metastases

We treated 183 patients who had brain metastases with whole-brain radiation therapy (RT) and adrenocorticosteroids utilizing a new high-dose radiation protocol. Treatment produced neurological improvement in 135 patients (74%); there was no change in 37 (20%), and deterioration occurred in 11 (6%). Of those patients who improved, two-thirds maintained neurological improvement for the remainder of their lives or for at least nine months, and one-third relapsed. One-third of those who relapsed improved again with steroids or further RT. Clinical improvement paralleled tumor regression on CT scan. Despite the clinical response, median survival was only twelve weeks; 24% lived six months and 8% lived one year. Death resulted from progressive brain disease in 16% of the patients. Two-thirds of the patients died of advancing systemic disease in the setting of stable, improved neurological function. These data suggest that the majority of patients with brain metastases benefit from RT and that systemic cancer, not central nervous system disease, limits the length of life.

Acute parotitis and hyperamylasemia following whole-brain radiation therapy

Parotitis, an infrequent, previously unreported complication of whole-brain radiation therapy, was observed in 4 patients. The acute symptoms, which include fever, dry mouth, pain, swelling, and tenderness, are accompanied by hyperamylasemia. Among 10 patients receiving whole-brain irradiation, 8 had serum amylase elevations without symptoms. Both acute parotitis and asymptomatic hyperamylasemia result from irradiation of the parotid glands.