Osteopenic consequences of botulinum toxin injections in the masticatory muscles: a pilot study.

Patients with temporomandibular muscle and joint disorder (TMJD) increasingly seek and receive treatment for their pain with botulinum toxin (BoNTA; botulinum toxin A). Used intramuscularly in therapeutic doses, it produces localised paresis. Such paresis creates risk of reduced bone mineral density, or 'disuse osteopenia'. Animal studies have frequently used BoNTA as a model of paralysis to induce bone changes within short periods. Osteopenic effects can be enduring in animals but have yet to be studied in humans. This is the first study in humans to examine bone-related consequences of BoNTA injections in the masticatory muscles, comparing oral and maxillofacial radiologists' ratings of trabecular bone patterns in the condyles of patients with TMJD exposed to multiple masticatory muscle injection sessions with BoNTA to a sample of patients with TMJD unexposed to masticatory muscle injections with BoNTA. Cone-beam computed tomography (CBCT)-derived images of bilateral condyles were evaluated in seven patients with TMJD receiving 2+ recent BoNTA treatment sessions for facial pain and nine demographically matched patients with TMJD not receiving BoNTA treatment. Two oral and maxillofacial radiologists evaluated CBCT images for evidence of trabecular changes consistent with osteopenia. Both evaluators noted decreased density in all participants exposed to BoNTA and in none of the unexposed participants (P < 0.001). No other abnormalities associated with reduced loading were detected. These findings need replication in a larger sample and over a longer time period, to ensure safety of patients with TMJD receiving multiple BoNTA injections for their pain.

Immunologic studies in asymptomatic hemophilia patients. Relationship to acquired immune deficiency syndrome (AIDS).

Asymptomatic hemophilia patients receiving Factor VIII concentrate were found to have normal natural killer (NK) cells and B cells, and an inverted T helper/suppressor ratio due to an increase in cells of T suppressor phenotype. In contrast, a hemophilia patient with acquired immune deficiency syndrome (AIDS) exhibited nonfunctional NK cells, low B cells, and an inverted T helper/suppressor ratio due to very low numbers of T helper cells. Hemophilia patients on cryoprecipitate therapy exhibited normal immune parameters. A high percentage of hemophilia patients on both treatments had antibody to hepatitis B virus. The isolated finding of elevated levels of T suppressor cells in hemophilia patients receiving Factor VIII concentrate has not been recognized as an early indicator of impending AIDS, and longitudinal studies will be required to determine its clinical significance.

Effects of low-level X-radiation on 7,12-dimethylbenz[a]anthracene-induced lingual tumors in Syrian golden hamsters.

The effects of repeated low-dose-rate, high-dose-rate X-radiation of the head and neck on lingual tumor induction by 7,12-dimethylbenz[a]anthracene (DMBA) in Syrian golden hamsters were studied. Animals received either topical application as 0.5% DMBA in acetone on the lateral middle third of the tongue three times a week for 15 consecutive weeks, 20-R X-radiation exposures of the head and neck once a week for 15 consecutive weeks, or concurrent radiation and DMBA treatments for 15 consecutive weeks. Animals were examined visually at regular intervals, and all were killed 35 weeks after the start of treatments. All tissues were than examined histopathologically. Animals receiving radiation alone had no detectable changes. Animals receiving DMBA plus radiation had an excess of papillomas compared to animals receiving only DMBA (35% vs. 15%). In addition, an excess of nonlingual oral tumors (lip, gingiva, and floor of mouth) was found in DMBA-treated plus radiation-treated animals versus DMBA-treated animals. These results suggest that repeated, localized, low-level X-radiation exposures enhance chemical tumorigenesis in a variety of oral tissues of Syrian golden hamsters.

7,12-Dimethylbenz[a]anthracene adduct formation with Syrian hamster cheek pouch epithelial DNA: in vitro studies in organ explant culture.

Studies examined the binding of radiolabeled 7,12-dimethylbenz[a]anthracene (DMBA) to epithelial DNA of hamster cheek pouch (HCP) maintained in organ explant culture. Adduct formation was studied as functions of [3H]DMBA dose, of the time after single [3H]DMBA applications, and of the route by which the DMBA was administered--either topically or in the culture media. Total DMBA-DNA adduct formation [total binding index (TBI)] was determined by DNA-bound 3H activity, and qualitative binding characteristics were further studied by high-pressure liquid chromatography. [3H]DMBA was applied either in the culture media at concentrations of 0.005-0.5 micrograms/ml or topically in mineral oil or ethanol in doses of 0.005-0.5 micrograms to each tissue fragment. Histopathologic changes in DMBA-treated HCP fragments included substantial aberrations in maturation of cornified and keratin layers and focal squamatization and dysplasia of the basal epithelium--considerable tissue necrosis was encountered in the high-DMBA-dose groups. Dose-response data were qualitatively similar among treatment types, with the greatest TBIs in topical ethanol groups and the lowest TBIs in culture medium groups. Kinetics of adduct formation and removal showed a rapid increase in TBIs to peak values at 24-72 hours followed by a biphasic decrease in TBIs, which leveled off at 7%-20% of peak values at 120-240 hours. Chromatographic analyses of selected samples at various times from all treatment groups showed three major peaks that are likely to be the same 1,2,3,4-tetrahydro-3,4-dihydroxy-1, 2-oxide-deoxyribonucleoside adducts observed in other rodent in vivo and cell culture systems. These results are consistent with those of other laboratories studying DMBA-DNA interactions and suggest that in vitro studies of DMBA-treated HCP explants are useful in studying the molecular nature of DMBA-DNA interactions in oral mucosal carcinogenesis.

DNA adduct formation by 7,12-dimethylbenz(a)anthracene in Syrian hamster cheek pouch epithelium in vivo.

Studies examined the in vivo binding of radiolabeled 7,12-dimethylbenz(a)anthracene (DMBA) to hamster cheek pouch epithelial DNA. Adduct formation was studied as functions of [3H]DMBA dose and of the time after single [3H]DMBA applications in mineral oil. Total DMBA-DNA adduct formation was determined by DNA-bound 3H activity, and qualitative binding characteristics were further studied by high-pressure liquid chromatography. Adduct formation 24 h after single [3H]DMBA applications rapidly increased from DMBA concentrations of 0.05-5.0 micrograms. While binding also increased from DMBA concentrations of 5.0-50.0 micrograms, the variability in adduct formation at 50.0 micrograms was considerable. Adduct formation following single 5.0-micrograms [3H]DMBA applications rose slowly to a peak value of 76 pmol DMBA/mg DNA at 36 h. This level decreased very slowly in a biphasic manner through 240 h, at which time the adduct levels were 23% of maximum. Adduct levels of 1.5 pmol/mg DNA were measured as late as 5 wk after a single 5.0-micrograms [3H]DMBA application. Chromatographic analyses of the 24-, 36-, and 96-, and 240-h samples showed three major peaks which are likely to be 1,2,3,4-tetrahydro-3,4-dihydroxy-1,2-oxide-deoxyribonucleoside adducts. While these analyses were limited by the small amounts of radioactivity which could be retrieved from [3H]DMBA-treated pouches, the study suggests that the DMBA-induced hamster cheek pouch carcinoma may be useful in some molecular in vivo studies of chemical-DNA interactions in carcinogenesis.

Anatomical and functional vascular changes in hamster cheek pouch during carcinogenesis induced by 7, 12-dimethylbenz(a)anthracene.

Anatomical and functional vascular changes during hamster cheek pouch carcinogenesis were studied by light microscopy; scanning electron microscopy of vascular casts; transmission electron microscopy of cheek pouch capillaries; and fractional distributions of 51Cr-erythrocytes, 125I-human serum albumin, and 86RbCI which were used to determine vascular volume, permeability, and perfusion. Histopathological changes and focal capillary changes in vascular casts were measured quantitatively by an image analyzer. Male Syrian hamsters received 0.5% 7,12-dimethylbenz[a]anthracene (DMBA) in mineral oil for 11 weeks and were sacrificed at periodic intervals from 2 to 20 weeks after initial treatment. Simple hyperplasia was first seen at Week 1. The area of hyperplastic epithelium, expressed as percentage, increased to about 60% by Week 8 and then decreased to 30% at Week 20. Dysplastic foci were first seen at Week 2. The percentage of the area of dysplasia increased with time to 41% at Week 20. Squamous cell carcinomas occurred from Week 10, increased with time, and were found in all animals at Week 20. Vascular cast diameters of normal-looking capillaries were larger during than after DMBA treatment. Type 3 vascular proliferations were found beneath dysplasia and cancer. Capillaries beneath simple hyperplasia and type 3 capillaries beneath dysplasia and cancers were dilated but not fenestrated. Changes in vascular volume were independent of changes in permeability and perfusion and also occurred in contralateral untreated pouches of treated animals. While 86Rb values initially correlated with 125I values, the 86Rb values were unstable in intermediate and later time periods. Changes of vascular volume were accompanied initially by the presence of DMBA and were coincident with increased areas of dilated capillaries beneath simple hyperplasia and later with areas of type 3 capillary proliferation beneath dysplasia and cancer. Changes of vascular permeability were related to inflammation indices throughout the study. DMBA may lastingly alter capillary endothelium in a manner which allows or aids in its subsequent dilatory and proliferative responses to angiogenic stimulation from malignant tumors, and possibly from premalignant or malignantly transformed cells.

Possible mechanistic roles of anatomical and functional vascular changes in rat urinary bladder carcinogenesis induced by N-butyl-N-(4-hydroxybutyl)nitrosamine.

Anatomical and functional vascular changes during rat urinary bladder carcinogenesis were studied by scanning electron microscopy of vascular casts, transmission electron microscopy of bladder capillaries, and fractional distributions of 51Cr-erythrocytes, 125I-human serum albumin, and 86RbCl which were used to determine vascular volume, permeability, and perfusion. Histopathological changes and focal capillary changes in vascular casts were measured quantitatively by an image analyzer. Male Wistar rats received 0.05% N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN) in their drinking water for 8 weeks and were then maintained on tap water without BBN for an additional 32 weeks. Simple hyperplasia was first seen at Week 2. The percentage of the area of hyperplastic epithelium increased to about 95% by Week 8 and then decreased to 4 to 6% at Weeks 20 or 40. Papillary or nodular hyperplasia was first seen at Week 6. The percentage of the area of papillary or nodular hyperplasia increased with time to 31.0% at Week 40. Papillary transitional-cell carcinomas were found from Week 20, increasing with time, and their incidence was 100% after Week 35. Vascular cast diameters of normal-looking capillaries were larger during than after BBN treatment. Type 3 vascular proliferations were found beneath papillary or nodular hyperplasia and cancer. Capillaries beneath simple hyperplasia and type 3 capillaries beneath capillary or nodular hyperplasia and cancers were fenestrated and dilated. Changes in vascular volume were independent of changes in permeability and perfusion. Best-fit curve analyses showed the maximum vascular volume at 8 weeks and minimum at 25 weeks, and the permeability maxima at 4 and 25 weeks with minima at 15 and 32 weeks. While 86Rb values correlated 125I values (r = 0.58), they were unstable in intermediate time periods. Changes of vascular volume were coincident initially with increased areas of dilated capillaries beneath simple hyperplasia and later with areas of type 3 capillary proliferation beneath papillary or nodular hyperplasia and cancer. Changes of vascular permeability were related to inflammation indices throughout the study. Increases in permeability were coincident with fenestrated capillaries beneath simple hyperplasia in early stages, and subsequently with fenestrated type 3 capillaries beneath papillary or nodular hyperplasia and cancer. BBN appears to cause alterations in vascular volume via induction of capillary dilation and also possibly by enhancing the responsiveness of host endothelium to angiogenic stimulation from neoplastic or preneoplastic tissues.

99MTc-diphosphonate bone imaging and uptake in healing rat extraction sockets.

Clinically positive bone scans of the jaws may result from a variety of benign dental conditions. An experimental system for studying radionuclide imaging and uptake in the jaws of rats was developed. Sequential 99mTc-diphosphonate bone scans and radionuclide uptake determinations were performed on rats after standardized extractions of their mandibular left first molars. Positive bone scans were seen 4-16 days after molar extraction, and increased radionuclide uptake was found in the healing extraction wounds 4-42 days after the extraction. Conventional radiography and histology fail to show unusual bony architecture in extraction sockets at such times. These results correlate with clinical findings in patients and suggest that human beings may have positive bone scans for several months after dental extraction.

Improvement of reduced left ventricular diastolic compliance in ischemic heart disease after successful coronary artery bypass surgery.

To determine the effects of myocardial revascularization on decreased left ventricular diastolic compliance consequent to chronic stable coronary artery disease, 15 patients with patent coronary artery bypass grafts (Group I) were compared with 8 patients with occluded grafts (Group II) studied before and after operation. In addition, eight normal patients served as controls. Left ventricular diastolic compliance was assessed by: (1) total observed diastolic compliance: stroke volume (V) related to left ventricular diastolic pressure (P) change (deltaV/deltaP) normalized for end-systolic volume; (2) left ventricular stiffness index of passive elastic modulus (a equals slope of deltaP/deltaV related to mean left ventricular diastolic pressure); and (3) fractional pattern of left ventricular filling. All patients had normal sinus rhythm and none had preoperative or postoperative mitral regurgitation. The two groups with coronary disease were well matched preoperatively for ventricular function, volumes, mass, segmental contraction and compliance. Ejection fraction increased in Group I (0.56 preoperatively to 0.65 postoperatively, P less than 0.05) but was unchanged in Group II (0.63 To 0.61, P greater 0.05). Postoperative indexes of left ventricular compliance improved in Group I: (1) 0.110 to 0.150 (P less 0.05); (2) 0.030 TO 0.019 (P less 0.05); and (3) 37 to 30 percent filling during last one third of diastole (P less 0.05). These indexes were unchanged postoperatively in Group II: (1) 0.109 to 0.102 (P greater 0.05); (2) 0.033 to 0.039 (P greater than 0.05); and (3) 36 to 41 percent (P greater 0.05). Compliance indexes were not altered (P greater 0.05) in a subset of seven patients in Group I with preoperative or intercurrent myocardial infarction. Thus, this investigation demonstrates the relatively reversible nature of abnormal left ventricular compliance after successful coronary artery bypass surgery in certain patients with ischemic heart disease.

Single, split and fractionated dose X-radiation-induced malignant transformation in A31-11 mouse BALB/3T3 cells.

Studies were conducted to determine the effects of a single, split and fractionated doses (separated by 1-h intervals) of 100 rad of X-irradiation on the morphological transformation of BALB/c 3T3 clone A31-11 mouse fibroblasts grown in media containing calf serum. Both spontaneous and radiation-induced transformation levels were lower for these cells grown in the cell-serum containing media than previously reported for these cells grown in fetal calf serum containing media. In the studies reported here, cells were irradiated either as density-inhibited plateau phase cultures or as low density cultures at 10-14 h after being reseeded from confluent dishes. We observed that a 4-fraction 100-rad dose resulted in a reduced yield of transformants compared to a single dose of 100 rad when plateau phase cultures were utilized for the radiation exposures, but not in low density cultures in which the cells were allowed to proliferate during the radiation exposures, these results suggest that the growth phase of the cells can play a major role in determining the yield of transformants induced by fractionated doses of radiation. It is noteworthy that, for the other data obtained in these studies, in none of 12 different experimental points (involving 5 separate experiments) did a fractionated dose protocol result in a reduced yield of transformants when compared to a single dose protocol.

Identification and quantification of human kidney atrial natriuretic peptide receptors.

The present study determined 125I-label atrial natriuretic peptide (ANP) binding sites in human kidney glomerular and papillary membranes. The membranes were prepared from non-malignant renal tissue obtained at nephrectomy of patients with renal carcinoma. To evaluate the proportion of ANP receptor classes ANP-R1 (ANPR-A, -B) versus ANP-R2 (ANPR-C), competitive binding studies were performed using [125I]-ANP in the presence of increasing concentrations of ANP or an internally ring-deleted analog, des(Gln116, Ser117, Gly118, Leu119, Gly120)ANP(102-121), called C-ANP, which binds selectively to ANPR-C receptors. Analysis of the competitive binding curve with ANP in glomerular membranes suggested the presence of one group of high-affinity receptors with dissociation constant Kd = 26 +/- 12 pmol/l and density Bmax = 101 +/- 47 nmol/kg protein. A decrease of 10-30% in Bmax with no change in Kd was obtained in the presence of excess (10(-6) mol/l) C-ANP, suggesting the existence of a small amount of a second class of receptors, the ANPR-C class. The densities of ANPR-A, -B versus ANPR-C receptors in human glomeruli, calculated from competitive inhibition experiments, were 75 +/- 42 and 22 +/- 16 nmol/kg protein (N = 8). Autoradiography of the sodium dodecyl sulfate polyacrylamide gel electrophoresis under reducing conditions showed two bands: a highly labeled 130kD band and a weakly labeled 66 kD band, both displaced by ANP. Only the 66-kD band was displaced by the C-ANP analog. Human papilla membrane, as shown by competition binding studies and SDS gel electrophoresis, presented only one class of receptors with Kd = 40 +/- 23 pmol/l (mean +/- SD, N = 3) and Bmax = 17 +/- 6.3 nmol/kg protein.(ABSTRACT TRUNCATED AT 250 WORDS)

Venous aneurysm, arterial dysplasia, and near-fatal hemorrhages in neurofibromatosis type 1.

Venous aneurysms are rare and usually develop following trauma. This report describes an aneurysm of the internal jugular vein that was associated with dysplasia of the cervical arteries, in a patient with neurofibromatosis type 1 (NF1). The finding of neurofibromatous tissue in the wall of the aneurysm as well as in small veins, suggested that the venous aneurysm was caused by the neurofibromatous invasion. No features of the dysplasia encountered in arteries of NF1 lesions were observed in the aneurysm or veins. During and after surgical excision of the aneurysm, the patient developed massive hemorrhages that required two reexplorations and evacuations of cervical hematomas. During surgeries, the bleeding was difficult to control because of excessive friability of the blood vessels. We suggest that the increased vascular fragility in this patient was caused by the NF1-associated arterial dysplasia and by the neurofibromatous venous invasion. Despite the vascular invasion by tumor, there is no evidence of malignancy or malignant transformation in this NF1 patient after a 10-year follow-up.

Rapid overdrive pacing of refractory tachyarrhythmias in patients after open-heart surgery.

The efficacy of rapid ventricular pacemaker overdrive in the treatment of supraventricular and ventricular tachyarrhythmias is presented as a new approach to the management of these rhythm disorders inpatients after cardiac surgery. This mode of therapy is exemplified in the control of heart rate and return of normal sinus rhythm in patients with both types of tachyarrhythmias refractory to conventional antiarrhythmic agents. In addition, the pathogenesis and mechanisms of pacemaker overdrive in termination these rhythm disturbances are delineated.

Coagulation and fibrinolytic changes in evolving acute myocardial infarction treated by high-dose, brief-duration intracoronary or intravenous streptokinase.

Twenty-two patients were infused with 240,000 units streptokinase during a 60-minute period into the ostium of the infarct-related coronary artery (IC), and 23 patients were infused with 1,500,000 units streptokinase intravenously (IV) over 45 minutes; all infusions occurred within 12 hours of the patients' onset of chest pain. Thereafter, heparin was infused for 10 days. Serial coagulation and fibrinolytic parameters were studied over 46 to 72 hours after the streptokinase infusion. A generalized fibrinolytic state was produced in both groups as evidenced by a fall in fibrinogen and plasminogen levels, prolongation of thrombin and reptilase clotting times, a rise in fibrinogen degradation products, and a shortening of the euglobulin lysis time. Recovery to preinfusion levels was similar in both groups of patients. Hemorrhagic complications requiring blood replacement occurred in 7/23 (30%) treated IC, and 4/23 (17%) in the IV group.

The measurement of fibrinogen by the DuPont aca and Dade methods in patients receiving streptokinase infusions.

To assess the discrepancies noted in fibrinogen measurement by the DuPont aca and Dade methods, nine patients receiving streptokinase (SK) by either the intracoronary (IC) (240,000 IU/60 minutes) (two patients) or intravenous (IV) (1,500,000 IU/45 minutes) routes (seven patients) for acute myocardial infarctions were studied over 48-72 hours. All nine patients showed a rapid and profound fall in fibrinogen to unrecordable levels (30 mg/dL) by the Dade method. Three patients showed a similar response to unrecordable levels (less than 50 mg/dL) with the DuPont aca method. Six others had less of a decrease with the DuPont aca method compared with the Dade method. One patient showed a gradual fall by the DuPont aca method to reach 60% of the preinfusion level at 30 hours, whereas the minimal value by the Dade method, 81% of the preinfusion level, was reached within 12 hours. There was no difference in fibrinogen levels by the Dade method after absorption of heparin-like activity with triethylamino ethyl (TEAE) cellulose. Fibrinogen degradation products (FDPs) were elevated in all patients post-SK infusion. These studies show that fibrinogen estimation by DuPont aca and Dade methods may yield discrepant results in approximately 66% of patients treated with SK. This may have some clinical relevance to clinicians who rely on the DuPont aca fibrinogen estimation to monitor effectiveness of SK therapy.

Wide variation in serum anion gap measurements by chemistry analyzers.

The traditional anion gap [AG = Na-Cl-(total CO2)] mean value of 12 mEq/L was established during the 1970s with analyzer methods that are no longer used widely. No studies have systematically compared mean AG values from analyzers in current use. We used data from healthy subjects obtained from 27 clinical laboratories, 5 manufacturers, and 8 publications to compute mean AG values from 1970s analyzers and 8 current analyzers. We also compared mean AG values by evaluating Na, Cl, and total CO2 data from the College of American Pathologists Chemistry Surveys (1990-1996). Data from healthy subjects showed that overall mean AG values of the 9 analyzers ranged from 5.9 to 12.4 mEq/L. The pooled (i.e., average) AG SD was 2.3 mEq/L. We then used the data of the Surveys and the mean value from 1 analyzer to compute predicted mean values for the other 7 current analyzers. Almost all mean AG values predicted from the Surveys agreed (within 1.5 mEq/L) with mean values from healthy subjects. These results show that mean values of analyzers vary widely, indicating that analytic bias strongly influences the AG. The results should be a useful guide for the AG measurements that can be expected from different analyzers.

Low level X-radiation effects on carcinogenesis by 7,12-dimethylbenz(a)anthracene in Syrian hamster cheek pouch epithelium: acute vs fractionated radiation dose studies.

Studies examined the effects of acute and fractionated low to moderate level X-ray exposures on hamster cheek pouch carcinogenesis in vivo by 7,12-dimethylbenz(a)anthracene (DMBA). Animals were grouped by treatment as follows: acute doses of 0.85-3.40 Gy X rays; 17 once weekly doses of 0.01-0.20 Gy X rays (fractionated radiation); topical DMBA for 10 weeks; DMBA plus fractionated radiation starting together; DMBA plus acute radiation in Week 1 or 10 of DMBA treatments; and sham irradiation, DMBA vehicle, or anesthesia controls. After 44 weeks, hamsters were sacrificed, and their cheek pouches were excised, serially sectioned, and examined by light microscopy for histopathology. No histologic changes were observed in radiation-only hamsters. Carcinoma incidences in DMBA-only groups ranged from 45 to 60%. Carcinoma incidences were greater in groups receiving DMBA plus fractionated radiation than in groups receiving either acute radiation + DMBA or DMBA alone. Carcinoma incidences in acute radiation plus DMBA groups were lower than those in DMBA-only groups. These results suggest complex interactions between radiation and DMBA, perhaps with radiogenic cell killing being a principal factor in acute radiation + DMBA groups, and reciprocal additive or synergistic effects of radiation and DMBA on cancer induction and manifestation in fractionated radiation + DMBA groups.

Low-level X-radiation effects on functional vascular changes in Syrian hamster cheek pouch epithelium during hydrocarbon carcinogenesis.

Effects of repeated low-level X radiation on functional microvascular changes in hamster cheek pouch epithelium during and following carcinogenesis by 7,12-dimethylbenz[a]anthracene (DMBA) were studied. Prior studies showed enhancement of such carcinogenesis by repeated 20 rad head and neck X-radiation exposures, and it was proposed that one possible mechanism was radiogenic alteration of the functional microvasculature in a manner which favored subsequent tumor development. Hamsters were treated with either radiation, DMBA, radiation + DMBA, or no treatment. Animals were sacrificed at 3-week intervals from 0 to 39 weeks after treatments began. Pouch vascular volume and permeability changes were studied by fractional distributions of radiotracers and were analyzed by a variety of statistical methods which explored the vascular parameters, treatment types, elapsed time, presence of the carcinogen, and histopathologic changes. All treatments resulted in significant changes in vascular volume with time, while only DMBA treatments alone resulted in significant changes in vascular permeability with time. Prior to the appearances of frank neoplasms, volumetric changes in DMBA only and radiation only groups were similar, while volume changes in DMBA + radiation groups increased slowly to a peak later than in other groups and then declined steadily to levels similar to the radiation only group. As in prior studies, there were significant vascular volume differences between DMBA and DMBA + radiation groups of tumor-bearing cheek pouches. DMBA maxima were significantly higher than those of DMBA + radiation. Radiation significantly affected DMBA-associated vascular volume and permeability changes during carcinogenesis. Several possible explanations for the relationship of these changes to the enhancement of DMBA carcinogenesis include: radiation blocking normal capillary proliferative and/or dilatory responses to inflammation secondary to neoplastic changes; radiation-induced focal increases in the pericapillary connective tissue histohematic barrier, stimulating angiogenesis but reducing nutrient diffusion; radiation exposures sensitizing vascular endothelium to subsequent angiogenic stimulation from premalignant tissues; DMBA vascular and epithelial effects partially or completely blocking radiation effects on epithelial and/or endothelial cells; and radiation damage to vessel walls partially or fully inhibiting normal physiologic mechanisms of repairing DMBA damage to the vessels.

Mutation spectrum in gamma-irradiated shuttle vector replicated in ataxia-telangiectasia lymphoblasts.

Cells from ataxia-telangiectasia (AT) patients are hypersensitive to the lethal effects of ionizing radiation. To assess radiation mutagenesis in these cells, the SV40-based shuttle vector, pZ189, was used to analyze gamma-ray-induced mutations following the plasmid's replication in AT lymphoblasts. Progenies from the AT line GM2783 exposed to 50 Gy showed a mutation frequency of 7.6 x 10(-3), 63-fold over background; surviving plasmids were 3.4% of control. Both values were essentially the same as those of irradiated plasmids replicated in a normal lymphoblast line, GM606. In addition, pZ189 exposed to 25 Gy of gamma radiation and replicated in another normal lymphoblast line and in cells of two additional AT lymphoblast lines showed similar mutation frequencies and percentages of surviving plasmids. Qualitative comparison of plasmid mutations from AT and normal cells showed no significant differences, indicating that the damaged DNA was repaired with similar fidelity in AT and normal cells. These studies suggest that there is no correlation between the enhanced sensitivity of AT cells to killing by ionizing radiation and gamma-radiation-induced mutagenesis of plasmid DNA processed in these cells.

The euglobulin lysis time test: an ineffectual monitor of the therapeutic inhibition of fibrinolysis.

In two clinical situations associated with hyperfibrinolysis the administration of antifibrinolytic drugs resulted in clinical haemostasis. The dilute clot lysis time and fibrin plate activity test but not the euglobulin lysis time reflected this control of excessive fibrinolysis by the antifibrinolytic drugs. The inhibition by epsilon-amino-caproic acid (EACA) of hyperfibrinolysis induced in vitro was reflected by the dilute clot lysis time but not by the euglobulin lysis time. Paper chromatography of the supernatant and euglobulin fractions as prepared for the euglobulin lysis time test from plasma with added EACA demonstrated that some 85% of the EACA was present in the supernatant, normally discarded during the test. Similarly, cellulose-acetate electrophoresis of the supernatant and euglobulin fractions from plasma containing Trasylol demonstrated the drug in the supernatant only. These findings indicate that when acetic acid is added to plasma containing EACA or Trasylol only a small proportion of the drug is precipitated with the euglobulin fraction. The euglobulin lysis time is thus an inaccurate index of the neutralization of hyperfibrinolysis by antifibrinolytic drugs.