Reirradiation tolerance of the immature rat spinal cord.

The dose dependence and time course of long-term recovery in the cervical spinal cord of 3-week-old rats was investigated, and compared with the recovery in adults rats. At intervals of 1 to 168 days after initial irradiation of the cervical spinal cord at the age of 3 weeks, reirradiation experiments were performed to test the pattern of long-term recovery in immature spinal cord. The single dose ED50 for white matter mediated paresis was about 21 Gy for 3-week-old as well as adult rats, although the latency to paresis development increased from about 90 days in 3-week-old rats to about 250 days in adult rats.

Radiation tolerance and fractionation sensitivity of the developing rat cervical spinal cord.

To investigate the influence of age at irradiation on single dose radiation tolerance and fractionation sensitivity, the cervical spinal cord of rats was irradiated at the age of 1 week and at 15-18 weeks (adult). While the main histological lesions seem to be comparable after irradiation at the two ages, differences were found in single dose tolerance, latency to paresis due to white matter lesions, and fractionation sensitivity. The 50% effect dose (ED50) for single dose irradiation at one week was 19.

Accelerated fractionation radiotherapy for laryngeal cancer, acute, and late toxicity.

The acute toxicity of an accelerated radiotherapy scheme was compared with a conventional schedule. Eighteen patients with squamous cell carcinoma of the larynx were treated with accelerated fractionation radiotherapy. An average reduction of overall treatment time of 11 days was accomplished by giving 2 fractions a day during the last part of the treatment.

Irradiation in vitro discriminates between different O-2A progenitor cell subpopulations in the perinatal central nervous system of rats.

The effects of X irradiation on oligodendrocyte-type-2-astrocyte (O-2A) progenitor cells derived from different regions of the perinatal central nervous system (CNS) of rats were investigated in vitro. The O-2A progenitor cells can differentiate into either oligodendrocytes or type-2 astrocytes. The depletion of these cells could lead to demyelination, seen as a delayed reaction after irradiation of the CNS in vivo.

Temporal sequence of early alterations in rat lung following thoracic X-irradiation.

The temporal patterns of several responses in the lungs of groups of rats administered two different thoracic doses of X-rays (7.5 and 15 Gy) were examined during a time frame within which radiation pneumonitis develops (1-13-week period) in order to assess for potential interrelationships among the responses. Endpoints surveyed included lung gravimetric and volumetric changes, changes in lavaged alveolar macrophage (AM) numbers, interstitial accumulations of mast cells (MC), and alterations in the amounts of lavaged phospholipids (PL), protein (P), and histamine (H).

[The modification of the mechanically loaded periodontium during orthodontically induced tooth movement with nonsteroidal anti-inflammatory agents in an animal experiment].

In a total of 123 female adult Wistar rats the first upper molar was moved by orthodontics for more than 28 days. This orthodontically stimulated tooth movement was influenced by local application of Cu-salicylate, Cu-indomethacin or epsilon-Aminocapronacid. The application of Cu-salicylate and Cu-indomethacin caused reduced tooth movement, a decrease in osteoclasts in the pressure region of the periodontium, and an increase of hydroxyproline in the desmodont.

Non-invasive in vivo localized 1H spectroscopy of human astrocytoma implanted in rat brain: regional differences followed in time.

Human astrocytoma cells were cultured and inoculated into the rat brain. From the pre-clinical to the terminal state, tumour growth was monitored by in vivo MR imaging and by localized water-suppressed 1H spectroscopy (0.12-0.

Radiosensitivity of glial progenitor cells of the perinatal and adult rat optic nerve studied by an in vitro clonogenic assay.

The cellular basis of radiation-induced demyelination and white matter necrosis of the central nervous system (CNS), is poorly understood. Glial cells responsible for myelination in the CNS might be the target cells of this type of damage. Glial cells with stem cell properties derived from the perinatal and adult rat CNS can be cultured in vitro.

Estimation of repair parameters in mouse lip mucosa during continuous and fractionated low dose-rate irradiation.

The present study investigated the effect of fractionated low dose-rate (FLDR) treatments in mouse lip mucosa, a typically early reacting tissue. The relation between dose-rate and fractionation effect has been assessed with various interfraction intervals and dose-rates. A fixed overall treatment time of 10 h has been used for the present continuous and fractionated irradiation experiments with corresponding dose-rates of 3.

An in vitro clonogenic assay to assess radiation damage in rat CNS glial progenitor cells.

Normal glial progenitor cells can be isolated from the rat central nervous system (CNS) and cultured in vitro on a monolayer of type-1 astrocytes. These monolayers are able to support and stimulate explanted glial progenitor cells to proliferate. Employing these in vitro interactions of specific glial cell types, an in vivo-in vitro clonogenic assay has been developed.

DNA strand breaks in human leukocytes induced by chemotherapy and total body irradiation.

The occurrence of DNA strand breaks and/or DNA alkali-labile sites in peripheral blood leucocytes was demonstrated ex vivo in three patients during and after bone marrow ablative chemotherapy and total body irradiation (TBI) with use of fluorometric analysis of the DNA unwinding rate in alkaline solution (FADU assay). DNA damage was apparent after cyclophosphamide administration and after TBI, related to the amount of the applied dose. In vivo repair occurred within 24 hours, although not to pretreatment values.

Radiobiology of pions in comparison with other heavy particles.

Our recent data on late effects of pions in spinal cord, lung and rectum in rodents is presented with reference to other high-LET radiations. Unlike high-LET radiations such as neutrons and neon ions, the RBE for late effects of pions (up to 1.5) is not found to be significantly different from acute effects.

Effects of high dose intraperitoneal cytosine arabinoside on the radiation tolerance of the rat spinal cord.

The effect of intraperitoneal high dose (9 g/kg) Cytosine Arabinoside (Ara-C) on the early delayed radiation response of the rat cervical spinal cord has been studied. When given 2 hrs before irradiation, systemically administered Ara-C significantly reduces the isoeffect doses for the induction of paralysis due to white matter necrosis by a factor of approximately 1.2 for both a single irradiation treatment and for a two fraction irradiation with 24 hr interval.

Tolerance of spinal cord, lung and rectum after fractionated pions and X-rays.

The chronic and late effects of fractionated negative pi-mesons (pions) and X-rays were investigated in rat spinal cord and rectum, and in mouse lung. Range modulated pions with a 6 cm Bragg peak were used at an average dose-rate of 0.2 Gy/min.

Effects of multifraction irradiation on the rat kidney.

Wag/Rij female rats were irradiated to the left kidney with single doses or 2, 4, 10, 20, or 40 equal dose fractions. The right kidney was removed 4 weeks after the last fraction. The kidney function was determined using three different parameters.

Radiation tolerance of the rat rectum to fractionated X-rays and pi-mesons.

A 2.5 cm segment of the rectum of female F344 rats was irradiated with up to 10 fractions of X-rays or pions. Transient signs of acute proctitis were followed by chronic rectal injury starting at about 2 months.

Late effects of fractionated pi-mesons compared to X rays on mouse lung.

Early and late delayed effects of up to 20 fractions of pions and X rays were investigated in the mouse lung. The whole thorax of female CD-1 mice was irradiated under Ethrane/O2 anesthesia. Respiration rate was measured by whole body plethysmography at biweekly to monthly intervals.

From 2 Gy to 1 Gy per fraction: sparing effect in rat spinal cord?

Recently published results, from this group, on rat cervical spinal cord, a late responding tissue, indicated no further sparing with lowering the fraction size from 2 to 1.8, 1.5, and 1.

Interaction of cisplatin and x-rays in rat kidney.

Cisplatin was administered as a single iv dose of 5 mg/kg in WAG/Rij female rats at intervals of 7 days or 30 minutes before or 7 days after graded irradiation of the left kidney. The unirradiated right kidney was removed 4 weeks after the x-ray treatment. Kidney function was determined by measuring urine osmolality and plasma urea.

Unilateral kidney irradiation and late retreatment with cis-dichlorodiammineplatinum (II): functional measurements with 99mtechnetium-dimercaptosuccinic acid.

A rat model was used to study renal function after unilateral kidney irradiations. The left kidney was irradiated with a single dose (6-14 Gy), 2 equal sized fractions (10-16 Gy total dose) or 4 equal sized fractions (12 to 21 Gy total dose). At regular time intervals after treatment, the left kidney function was assessed with the use of 99mTc-Dimercaptosuccinic acid for a period of about 1 year.

Interaction of cis-diamminedichloroplatinum and renal irradiation on renal function in the young and adult rat.

The interaction between single low doses of cis-diamminedichloroplatinum(II) (c-DDP) and renal irradiation (7.5, 10, 12.5 Gy) on renal function and systolic blood pressure (SBP) was investigated in young (3-4 weeks old, BW 45-65 g) and adult rats (over 12 weeks old, BW 230-290 g).

Hypertension after bilateral kidney irradiation in young and adult rats.

The mechanism of a rise in blood pressure after kidney irradiation is unclear but most likely of renal origin. We have investigated the role of the renin-angiotensin system and dietary salt restriction in the development of systolic hypertension after bilateral kidney irradiation in young and adult rats. Three to 12 months after a single X-ray dose of 7.

Is the rate of repair of radiation-induced sublethal damage in rat spinal cord dependent on the size of dose per fraction?

In the present study the possible dependency of the kinetics of repair of sublethal damage in rat spinal cord on the fraction size has been further investigated. A wide range of sizes of dose per fraction (1.7-17.

Radiation nephropathy in young and adult rats.

The effects of bilateral kidney irradiation were compared in young and adult rats. During a 1 year period after a single dose of 0, 7.5, 10, 12.