Radiation therapy toxicities.

Since the infancy of radiology and radiation therapy, reactions to radiation have been noted and followed, and attempts have been made to minimize these reactions. We have turned to radiobiologists to explain these reactions and to radiation oncologists to prevent or decrease the normal tissue effects of radiation therapy. Radiation toxicities are divided into early (acute) and late (chronic) reactions; however, it is important to note that severe toxicities are rare and occur typically in less than 5% of veterinary radiation therapy patients.

Radiation oncology of head and neck tumors.

Malignant tumors of the head and neck region occur commonly in veterinary medicine. Unfortunately, tumors in the head and neck can cause treatment dilemmas because many neoplastic entities at this site are locally aggressive. Additional local therapies such as radiation therapy are becoming commonplace as standardized therapies for many head and neck tumors in veterinary medicine.

The effect of Acemannan Immunostimulant in combination with surgery and radiation therapy on spontaneous canine and feline fibrosarcomas.

Eight dogs and five cats with histopathologically confirmed fibrosarcomas were treated with Acemannan Immunostimulanta in combination with surgery and radiation therapy. These animals had recurring disease that had failed previous treatment, a poor prognosis for survival, or both. Following four to seven weekly acemannan treatments, tumor shrinkage occurred in four (greater than 50%; n = 2) of 12 animals, with tumors accessible to measurement. A notable increase in necrosis and inflammation was observed. Complete surgical excision was performed on all animals between the fourth and seventh week following initiation of acemannan therapy. Radiation therapy was instituted immediately after surgery. Acemannan treatments were continued monthly for one year. Seven of the 13 animals remain alive and tumor-free (range, 440+ to 603+ days) with a median survival time of 372 days. The data suggests that Acemannan Immunostimulant may be an effective adjunct to surgery and radiation therapy in the treatment of canine and feline fibrosarcomas.

Pilot study of the effect of acemannan in cats infected with feline immunodeficiency virus.

Acemannan, a complex carbohydrate shown to stimulate interleukin-1, tumor necrosis factor alpha and prostaglandin E2 production by macrophages, has also demonstrated antiviral activity in vitro against human immunodeficiency virus, Newcastle disease virus and influenza virus. A pilot study was undertaken to determine acemannan's effect in 49 feline immunodeficiency virus (FIV) infected cats with clinical signs of disease (Stage 3, 4 or 5), 23 of which had severe lymphopenia. Cats received acemannan either by intravenous (Group 1) or subcutaneous (Group 2) injection once weekly for 12 weeks, or by daily oral (Group 3) administration for 12 weeks. Upon entry into the study, cats were randomly assigned to one of the three groups. Laboratory analyses were performed at the beginning of the study and at Weeks 6 and 12. Cats were allowed to continue with a predetermined maintenance regimen of acemannan after completing the 12-week study. Thirteen cats died during the course of treatment. Upon necropsy, the most frequent histopathologic findings were neoplastic, kidney and pancreatic disease. Friedman's two-way ANOVA test showed no significant differences in efficacy among groups administered acemannan by the different routes. Therefore, groups were combined and a signed-ranks test was used to determine changes over time. A significant increase was seen in lymphocyte counts (P < 0.001). Neutrophil counts decreased significantly (P = 0.007), as did incidence of sepsis (P = 0.008). When cats entering with lymphopenia were analyzed separately, a much greater increase in lymphocyte counts was noted (235%) compared with non-lymphopenic cats (42%). A survival rate of 75% was found for all three groups. Thirty-six of 49 animals are alive 5-19 months post-entry. These results suggest that acemannan therapy may be of significant benefit in FIV-infected cats exhibiting clinical signs of disease.

A case of murine typhus in Queensland.

OBJECTIVE: To present a case of murine (endemic) typhus, the first to be reported within the last 30 years in Australia. CLINICAL FEATURES: A 17-year-old pregnant woman presented with a viral-like illness and later developed a spotted rash, fever and headache. INVESTIGATION AND OUTCOME: Sera taken on Day 7 and Day 30 of the illness showed seroconversion to Proteus OX19 (Weil-Felix) and to Rickettsia typhi (by immunofluorescence), indicating recent infection with Rickettsia of the typhus group. Her illness was clinically compatible with murine typhus. She responded well to erythromycin and delivered a normal infant at term. CONCLUSION: Infection with Rickettsia typhi (murine typhus) still occurs in Australia. It can be diagnosed by means of specific serological tests for rickettsial disease, which are superior to the non-specific Weil-Felix test.

Fatal arterial gas embolism: detection by chest radiography and imaging before autopsy.

Two recent cases are reported from north Queensland of deaths from massive arterial gas embolism occurring in tourists scuba diving on the Great Barrier Reef. The diagnosis was established in each case by an external examination of the body, followed by a plain erect chest radiograph soon after death and before autopsy; in one of the cases it was further confirmed before autopsy by computed tomography (CT) of the head, neck and thorax. The diagnosis was also supported by analysis of a diving profile, inspection and investigation of diving equipment, and autopsy. In the light of previously published advice and reports, the experience gained from these two cases now dictates that investigation of an unexplained death occurring after exposure to, and change from, hyperbaric or hypobaric conditions, should begin with plain erect chest radiography on the body before autopsy. Combining this with a pre-autopsy supine chest film before standing the body erect, and CT scanning of the head, neck and chest, is also recommended.

Target cell and mode of radiation injury in rhesus salivary glands.

Morphological alterations of parotid and submandibular salivary glands of rhesus monkeys were studied 1-72 h and 16-40 weeks postirradiation (PI) with single photon doses of 2.5-15.0 Gy, or 10.2 Gy given in 6 fractions. Acute degeneration and necrosis of serous cells in both parotid and submandibular glands were clearly expressed by 24 h PI and occurred in a dose-related fashion. In submandibular glands, doses of 12.5 or 15.0 Gy damaged mucous cells, but to a considerably lesser extent than the serous cells in the same glands. No significant sparing was evident with dose fractionation. These observations demonstrate the unique sensitivity of serous cells which appear to undergo interphase cell death after irradiation. The results also show that late atrophy was the direct result of acute loss of serous acini and reflects a lack of regeneration of acinar cells receiving acute injury.

Unique radiosensitivity of serous cells in rhesus monkey submandibular glands.

The saliva of patients undergoing radiation therapy for head and neck cancer contains increased acidic mucosubstances associated with a reduced serous component. To assess the morphologic features of the acute radiation damage in serous versus mucous acinar cells, the mixed serous/mucous submandibular glands of 18 rhesus monkeys were studied 1-72 hours after irradiation with single doses of 2.5-15.0 Gy. Selective degeneration and necrosis of serous cells was observed with doses of 2.5-7.5 Gy. Doses of 10.0-15.0 Gy caused widespread destruction of whole serous acini, but only isolated mucous cells were affected. The lesions were clearly expressed by 24 hours. Transient exudation of neutrophils was replaced by plasma cells and lymphocytes. Examination at 16, 22 and at 40 weeks revealed that late atrophy was caused solely by loss of serous acini in glands treated with 7.5 and 10.0 Gy. Although both serous and mucous acini were reduced in glands treated with 12.5 and 15.0 Gy, the atrophy was mainly due to loss of serous acini. The finding that serous cells are more vulnerable to radiation injury than mucous cells provides a morphologic explanation for early and late changes in saliva composition after salivary gland irradiation.

Acute and late radiation injury in rhesus monkey parotid glands. Evidence of interphase cell death.

Acute and chronic salivary gland dysfunction are common sequelae of radiotherapy for head and neck cancer; but the associated morphologic changes, especially of the acute damage, have received relatively little study. For investigation of the morphologic characteristics of acute radiation injury to parotid glands, rhesus monkeys were studied 1-72 hours after parotid irradiation with single doses of 2.5-15.0 Gy. The acute damage from all doses was clearly expressed by 24 hours. Histologically, parotid glands irradiated with 2.5 or 5.0 Gy had random degeneration and necrosis of the serous acinar cells. Doses of 7.5-15.0 Gy produced widespread degeneration along with necrosis of whole acini. Serous cell damage was accompanied by neutrophilic inflammation that subsided after 24 hours to become replaced by plasma cell and lymphocytic infiltrates. Parotid glands receiving 7.5-15.0 Gy were atrophic at 16-22 weeks after irradiation and showed no recovery by 40 weeks. Although parotid acinar cells are well-differentiated nondividing cells, these observations show that they express lethal radiation injury in interphase within hours of receiving a radiation dose as low as 2.5 Gy. This is unlike most mammalian cells that express radiation injury during mitosis. Chronic atrophy is a consequence of this direct, irreversible, and early injury, rather than the result of radiation-induced changes in the vasculature.

Surgical and microscopic anatomy of parotid and submandibular salivary glands of rhesus monkeys (Macaca mulatta).

Wedge biopsy of the caudal borders of the parotid or submandibular salivary glands of rhesus monkeys avoids major nerves, ducts, and blood vessels. This is a minor surgical procedure that provides adequate material for in vitro studies and causes no significant postoperative complications. Gross and light microscopic anatomy of the rhesus and human salivary glands are similar. We have concluded that rhesus monkeys are good models for human salivary diseases, including radiation sialoadenitis.