The role of secretory granules in radiation-induced dysfunction of rat salivary glands

To investigate the possible role of secretory granules in radiation-induced salivary gland dysfunction, rats were pretreated with isoproterenol (5 mg/kg intraperitoneally) to degranulate salivary gland acini. At maximal depletion, salivary glands were locally irradiated with a single dose of 15 Gy of X rays. Parotid and submandibular/sublingual saliva samples were collected before and 1-10 days after irradiation. The lag phase, flow rate, concentrations of potassium and sodium, and amylase secretion were determined. Sham-treated, isoproterenol-treated and irradiated animals provided reference data. In the parotid gland, but not in the submandibular gland, protection against radiation-induced changes in flow rate and composition of saliva occurred after pretreatment with isoproterenol. Combining morphological data from a previous study with data from the current study, it is suggested that improvement of parotid gland function is attributed predominantly to a proliferative stimulus on acinar cells by isoproterenol and not to its degranulation effect. After pretreatment with isoproterenol, an earlier expression of radiation-induced acinar cell damage leading to death was observed, followed by a faster tissue recovery. Thus the proliferative stimulus on acinar cells may accelerate the unmasking of latent lethal damage, resulting in the earlier replacement of dead cells by new, functionally intact cells.

The role of secretory granules in the radiosensitivity of rat salivary gland acini--a morphological study

The aim of this study was to investigate the radiosensitivity of salivary gland tissue pretreated with isoproterenol to establish a status of depletion of secretory granules in acinar cells at the time of irradiation. Nuclear aberrations and cell lysis were taken as parameters for cell death. Local X irradiation with a single dose of 15 Gy induced comparable early morphological changes in the rat parotid and submandibular glands. During the first day after irradiation, the most obvious changes were degranulation of serous cells and induction of nuclear aberrations in both the secretory (serous as well as mucous) and intercalated duct compartment. Subsequently, progressive lysis occurred in secretory units but not in intercalated and striated ducts. Recovery of tissue integrity was observed from day 6. Early radiation-induced cell death was not reduced by isoproterenol-induced degranulation of acinar cells before irradiation. Subsequent recovery from radiation damage seemed to occur earlier in parotid glands but not in submandibular glands pretreated with isoproterenol. From the present study it is concluded that the radiosensitivity of serous salivary gland acini is not dependent on the presence of secretory granules at the time of irradiation. There was some evidence for a faster recovery from radiation damage observed after pretreatment with isoproterenol which may be the result of drug-induced stimulation of cell proliferation.

Radiation-induced cell proliferation in the parotid and submandibular glands of the rat

Repopulation of tissues with cells at damaged sites is an important feature in the recovery of radiation-induced tissue injury. To obtain insight into the regenerative process in salivary gland tissue, proliferative activity was measured as a function of time in the different epithelial cell compartments of rat parotid and submandibular glands after local X irradiation with a single dose of 15 Gy. Bromodeoxyuridine-labeling indices were determined before and 10 h and 1, 3, 6, 10, 15, 20 and 30 days after irradiation. In both glands, X irradiation caused cell death and cell cycle delay manifested during the first day. Three days after irradiation, cell proliferation started in the intercalated duct. Six days after irradiation, proliferation was also observed in acinar and granular convoluted tubule cells. The striated ducts showed proliferative activity starting at day 6 (parotid) and day 10 (submandibular), respectively. The results of this study suggest that after 15 Gy of X rays repopulation takes place in all cell compartments. From the present study it cannot deduce if these cells are originating solely from progenitor cells residing in the intercalated duct or if cells of the other compartments are also stimulated. Proliferative activity was found to be higher in the intercalated duct compartment of the parotid gland than of the submandibular gland, which may be related to the suggested greater radiosensitivity and thus a greater demand for cell replenishment in the parotid gland.

Urinary retention in the elderly: a study of 100 hospitalized patients

OBJECTIVE

To estimate the prevalence of incomplete bladder emptying by the elderly and to determine its significance and its relationship to overflow incontinence.

DESIGN

Survey comparing groups with and without incomplete bladder emptying.

SETTING

A geriatric hospital ward.

PATIENTS

One hundred patients who were consecutively admitted, with an average age of 82.6 years.

MEASUREMENTS

A physical examination, perineal examination, micturition assessment, and evaluation of the post-voiding residual urine volume (PRUV) by ultrasonography at day 1 and day 8 following admission. One-channel cystometry and urine cultures were also done. Between-group comparison was performed between groups R (ie, PRUV greater than 50 mL) and C (ie, PRUV less than 50 mL).

MAIN RESULTS

The prevalence of PRUV greater than 50 mL was 34%. Group R patients presented with greater dependency; death was the final outcome of hospitalization in 36% of these cases (vs only 9% in group C). A high PRUV was not correlated with urinary tract infection or renal failure, but there was a strong, almost significant trend toward incontinence being more prevalent in R (57%) than in C (38%) (P = 0.06). Group R presented a hypotonic bladder in 45% of cases, evidenced by cystometry, versus 6% in group C.

CONCLUSIONS

In cases with a high PRUV, the utmost caution is necessary both in the diagnosis of overflow incontinence and in establishing a therapeutic approach. Incomplete bladder emptying is associated with a poor prognosis.

Role of lipid peroxidation and DNA damage in paraquat toxicity and the interaction of paraquat with ionizing radiation

Since the introduction of paraquat (PQ) as a herbicide in 1963, there have been many speculations concerning the critical lesion in PQ toxicity. Damage to membrane lipids might be an initial event leading to PQ-induced cell killing. The ability of PQ to induce lipid peroxidation was tested in liver homogenates of the mouse. Lipid peroxidation was indeed induced by PQ and shown to be dose dependent, starting to be significant at 2.5 mM. Subsequently, a possible correlation between lipid peroxidation and PQ-induced cell death was investigated in mouse fibroblasts (LM) and Ehrlich ascites tumour (EAT) cells using a clonogenic assay. It was found that in order to be cytotoxic PQ needs enzymatic activation (incubation at 37 degrees). In both cell lines, PQ-induced cell killing appeared to be dose dependent, starting at a dose of 0.5 mM. Supplementation of LM cells with the antioxidant vitamin E had no effect on PQ-induced cell killing and modification of the membranes of LM cells by incorporation of the polyunsaturated fatty acid 20:4 (arachidonic acid) did not sensitize the cells to PQ toxicity. PQ had no effect on the glutathione (GSH) level in EAT cells and complete GSH depletion by DL-buthionine-(SR)-sulfoximine could not sensitize the cells to PQ toxicity. In LM cells PQ-induced cell killing was enhanced after complete GSH depletion by DEM. This sensitization might, however, be attributed to the binding of DEM to proteins. From these results it seems unlikely that lipid peroxidation is the primary cause for PQ-induced cell killing. Another critical target in PQ toxicity is DNA. This possibility was investigated in EAT cells. PQ was found to induce DNA damage (detected by the alkaline unwinding assay) in the same dose range that caused cell death. A good correlation was obtained for cell killing after PQ treatment and DNA damage measured 2 hr after 37 degrees post-incubation. A proposed possible interaction between PQ and X-rays was also investigated. In EAT cells, X-ray-induced cell death was significantly enhanced by pre-incubation with PQ at doses of 0.5 mM and above. At the level of 10% survival an enhancement factor of 1.6 could be observed by treatment with 1 mM PQ when cell killing by PQ is not taken into account. Induction as well as processing of radiation-induced DNA damage seems to be unaffected by pre-incubation with PQ. The mechanism of radiosensitization by PQ is yet unclear.

Combined subtotal pancreatectomy with selective streptozotocin infusion--a model for the induction of insulin deficiency in dogs

Standardized models of type I diabetes-like insulin deficiency in larger laboratory animals hardly exist. It was therefore investigated whether stable long-term insulin deficiency in dogs can be induced by selective beta-cell destruction in a safe and reliable procedure without damage of other organs. In Beagle dogs, the diabetogenic response to systemic streptozotocin administration (38.5-28 mg/kg b.wt.) was tested. In addition, resection of corpus and cauda pancreatis in combination with selective streptozotocin perfusion (25 mg/kg b.wt.) of the remaining pancreas tissue was evaluated. Whereas systemic streptozotocin administration failed to destroy insulin secretion, but led to a variety of intoxication symptoms even in comparatively low doses (28 mg/kg b.wt.), the latter procedure resulted in a complete and persistent insulin depletion (basal serum immunoreactive insulin less than or equal to 3 microU/ml, no stimulated response) without toxic organ damage or other serious side effects. The dogs developed type I-like diabetes, which required continuous exogenous insulin substitution. From these results, subtotal pancreatectomy with selective streptozotocin perfusion of the remaining pancreas is proposed as a safe model of insulin deficiency in dogs, which should be further evaluated in experimental diabetology.

Mouse cytoskeletal gamma-actin: analysis and implications of the structure of cloned cDNA and processed pseudogenes

The nucleotide sequence corresponding to almost the whole of a mouse gamma-cytoskeletal actin mRNA was determined from overlapping cloned DNA copies derived from brain mRNA. Several gamma-actin processed pseudogenes were isolated from a library of cloned DBA mouse genomic DNA, and the nucleotide sequences of these were determined and compared with that of the cDNA. This showed that two of these pseudogenes had arisen from a gene duplication or amplification event, and indicated that they had subsequently undergone partial correction against one another. The relative ages of the pseudogenes were estimated on the basis of their percentage divergence from the cDNA sequence and these were compared with an estimation based on the number of presumed silent mutations in the cDNA since each pseudogene had arisen. Consistent results were obtained, except in the case of one pseudogene which also showed an anomalous regional distribution of differences from the cDNA sequence. One way of accounting for the features of this anomalous pseudogene is by postulating that it is derived from a second functional gene for gamma-actin, different from that represented by the cDNA described here.

[1-year prognosis of syncope and brief loss of consciousness in patients over 65. A multicenter study of 188 cases]

The one-year outcome of syncope and transient loss of consciousness was studied prospectively in 188 patients aged over 65 admitted to internal medicine departments. Thirty-seven patients (19.6 p. 100) died. This mortality rate at one year was 2.34 times higher than that of a non-hospitalized french population of the same age group (standardized mortality ratio, SMR = 2.34, P less than 0.001). The frequency of sudden death (7 cases) was much higher than that observed in the reference population (0.05 expected deaths, P less than 0.0001). Overmortality was clearly apparent in groups with an initial diagnosis of heart disease (SMR = 2.36, P less than 0.01) or neurological disease (SMR = 4.25, P less than 0.001). The relapse rate was 28 p. 100 globally and up to 43 p. 100 in cardiac patients. In the group with iatrogenic symptoms treatment was appropriately corrected in 86 p. 100 of the patients, and none of these relapsed. One year after the initial episode 11 p. 100 of the surviving patients had been institutionalized.

The ABO and Rhesus groups in the north of Nigeria

ABO and Rhesus blood group data were analysed from 43187 blood donors belonging to 34 ethnic groups, predominantly from northern Nigeria. This is the largest series to be reported on from the whole of West Africa. Group O was found in 46.6% of all those examined, but the numbers varied from 33.13% to 64.35% in different ethnic groups. Group A was found in 23.05% and Group B in 25.95%, but again there was much variation in the distribution of the blood groups in different ethnic groups. There was an overall frequency of 3.64% of Rhesus negatives, ranging from 1.4% to 8.72% in different ethnic groups. The results provide basic but useful information concerning many ethnic groups whose blood groups have not previously been reported.

[Prenatal diagnosis of a severe heart defect (author's transl)]

Report of the case of a 22 year old primigravida. At 37 weeks gestation an ultra-sound examination was carried out because of fetal bradycardia. An atrial septal defect was found with a complete atrial ventricle canal. (AV canal). These findings were corroberated at autopsy in addition a polyspienic syndrome with multiple thoracic and abdominal malformations was found. The antepartum diagnosis permitted a team approach to the case. The infant was immediately transferred to the cardiac centre where a pace maker was placed and angiography carried out. Ante-partum ultra-sound diagnosis of congenital heart disease permits optimal neonatal treatment.

Dyscalculia and elements of the developmental Gerstmann syndrome in school children

Fourteen (14) dyscalculic school children were drawn from a larger population of learning-disabled children. The subjects were divided into two groups, those with normal-or-better reading ability and those with dyslexia equal in degree to their dyscalculia. Both groups showed a variety of behavioral deficits in addition to those comprising Gerstmann's syndrome and were notably poor in auditory and visual discrimination and motor coordination. Good readers showed severely-impaired ability to make right-left discriminations, while the poor readers were average in this ability. Poor readers showed marked impairment of word fluency and hand writing, while good readers were average in this regard. The dyscalculia and reading deficits reported here appear unrelated to central-language impairment. Subjects with all four elements of the developmental Gerstmann's syndrome did not constitute an homogeneous behavioral group and were found among samples of both good and poor readers. The pattern of behavioral deficits shown by these subjects suggests cerebral impairment rather than slow maturation as a probable etiology. While the DGS is not useful as a behavioral description, its value as a possible localizing neurological sign cannot yet be ruled out.