Cell synchrony techniques. II. Analysis of cell progression data

CHO cells which have been sorted by mitotic detachment, centrifugal elutriation and fluorescence activated cell sorting have been followed for up to 14 hr by flow cytometry to examine their progression characteristics. Mathematical modelling techniques were used to provide quantitative estimates of the cell-cycle parameters. Mitotic detachment gives an 11.2-hr cycle time with mean transit times TG1, TS and TG2M equal to 3.2, 5.6 and 2.4 respectively. Cells prepared by central elutriation in an early G1 state have a 14-hr cycle time with TG1, TS and TG2M of 5.7, 6.0 and 2.3 hr. Populations prepared by centrifugal elutriation enriched in early S and late S and G2M have transit times of 2.7, 5.9 and 1.6 hr and 4.9, 6.7 and 2.1 hr with cycle times of 11.2 and 13.2 hr respectively. Cell sorting for a G1 population gives transit times of 9.8, 8.0 and 3.6 for an overall 21.4-hr cycle time.

Diagnosis of posttraumatic stress disorder in Viet Nam veterans: preliminary findings

Sixty-six Viet Nam veterans were evaluated for posttraumatic stress disorder. Several of the DSM-III criteria for the disorder, but no other clinical features, distinguished patients diagnosed as having the disorder from others. The findings tend to validate the DSM-III construct for this disorder.

Cell synchrony techniques. I. A comparison of methods

Selected cell synchrony techniques, as applied to asynchronous populations of Chinese hamster ovary (CHO) cells, have been compared. Aliquots from the same culture of exponentially growing cells were synchronized using mitotic selection, mitotic selection and hydroxyurea block, centrifugal elutriation, or an EPICS V cell sorter. Sorting of cells was achieved after staining cells with Hoechst 33258. After synchronization by the various methods the relative distribution of cells in G1, S, or G2 + M phases of the cell cycle was determined by flow cytometry. Fractions of synchronized cells obtained from each method were replated and allowed to progress through a second cell cycle. Mitotic selection gave rise to relatively pure and unperturbed early G1 phase cells. While cell synchrony rapidly dispersed with time, cells progressed through the cell cycle in 12 hr. Sorting with the EPICS V on the modal G1 peak yielded a relatively pure but heterogeneous G1 population (i.e. early to late G1). Again, synchrony dispersed with time, but cell-cycle progression required 14 hr. With centrifugal elutriation, several different cell populations synchronized throughout the cell cycle could be rapidly obtained with a purity comparable to mitotic selection and cell sorting. It was concluded that, either alone or in combination with blocking agents such as hydroxyurea, elutriation and mitotic selection were both excellent methods for synchronizing CHO cells. Cell sorting exhibited limitations in sample size and time required for synchronizing CHO cells. Its major advantage would be its ability to isolate cell populations unique with respect to selected cellular parameters.

An analysis of repeated sequence heterogeneity

High-resolution thermal denaturation was used to measure the heterogeneity within repeated DNA sequences. An analysis of combined denaturation/redenaturation experiments on mouse satellite DNA suggests the existence of two minor components, one of which does not appear in the prepared EcoRII monomer. The resolving power of the denaturation/redenaturation experiment is estimated and contrasted with that of the reassociation experiment, often used to estimate repeated sequence heterogeneity. A mathematical model of the redenaturation experiment was developed and applied to mouse satellite data; the results suggest that only one-fourth of the mismatched base pairs are energetically significant in the reduction of heteroduplex stability.

Pulmonary embolism secondary to venous thrombosis of the arm

Pulmonary embolism is described as an infrequent complication of axillary and subclavian vein thrombosis. We have reported our recent clinical experience with 14 patients admitted to the Harbor-UCLA Medical Center who had a clinical diagnosis of axillary and subclavian vein thrombosis documented by phlebography of the thrombosed arm. The causes of thrombosis were effort (three patients), trauma (three patients), drug abuse (four patients), underlying neoplastic disease (three patients), and congenital venous malformation (one patient). Pulmonary emboli were diagnosed by arteriogram, ventilation perfusion scans, and arterial blood gas abnormalities in five patients with respiratory symptoms for an incidence of 35.7 percent. Immediate anticoagulation with heparin, then switching to warfarin sulfate after 5 days, was the standard therapy in all patients. Follow-up examinations between 3 and 24 months demonstrated mild postphlebitic syndrome consisting of pain and minimal swelling in two patients. We conclude that pulmonary emboli may be a more frequent complication of axillary and subclavian vein thrombosis than has generally been recognized.

Neovascularity of a tracheal prosthesis/tissue complex

Permanent bioincorporation of a microporous tracheal prosthesis will require a stable blood supply to connective tissue supporting an epithelial surface. In experience with over 80 tracheal implants in dogs, we have observed that end-on ingrowth and epithelialization does not occur in the absence of lateral ingrowth, epithelialization is marked by the appearance of a subepithelial network of vessels, and this process must be well advanced by 6 to 8 weeks for long-term stability. These observations were extended by using microangiography to delineate the blood supply of the prosthesis/tissue complex. Six implants of bioelectric polyurethane with 10% gentamicin (3 cm length, 2 cm diameter, 1 to 1.25 mm wall thickness, 60 to 120 mu micropore diameter) were interposed in the dog thoracic trachea and wrapped with an omental pedicle. The aorta was perfused with a barium suspension at elective sacrifice between 10 weeks and 21 months. Radiographs of specimens were correlated with bronchoscopic, gross, and histopathological findings. Neovascularity of the prosthesis/tissue complex can be described in three categories: outer capsule, prosthetic wall, and inner lining. Outer capsule vessels were oriented circumferentially immediately adjacent to the prosthetic wall. They resembled arteries up to 75 mu diameter on microscopy and appeared to develop from the omentum with connections developing to the bronchial circulation. Prosthetic wall vessels up to 75 mu with thin muscular walls were noted to traverse the porous prosthetic wall. The inner lining had a network of subepithelial vessels that connected to the lamina propria vasculature of the native trachea across the anastomoses with vessels up to 120 mu in diameter. We conclude that the omentum provides an immediate blood supply and a base for early connective tissue ingrowth. Epithelialization occurs as early as 3 weeks on the favorable bed, accompanied by vascular connections to the existing lamina propria tracheal vessels. This dual organization of blood supply with connections across the prosthetic wall is probably important to long-term stability of healing.

The effect of antisecretagogues on gastric microflora

We examined the effect of cimetidine in altering gastric microflora in patients undergoing gastric resection for peptic ulcer disease. Ten patients had administration of cimetidine stopped at least six hours before surgery. Their mean gastric pH was 2.02 +/- 1.51, and 0.4 +/- 0.97 organisms were isolated per patient. Ten patients were maintained on a regimen of cimetidine and their mean gastric pH was 5.69 +/- 1.80, with 3.2 +/- 1.62 organisms isolated per patient. We reached the following conclusions: cimetidine alters the gastric pH of preoperative patients; cimetidine therapy is associated with an increase in gastric flora; stopping administration of cimetidine six hours before surgery reacidifies the stomach, decreases the number of organisms isolated from the stomach, and decreases the risk of septic complications.

Cytotoxic effects of vincristine on tumour subpopulations separated from pulmonary nodules

The cytotoxic and stathomokinetic effects of vincristine (VCR) on murine fibrosarcoma (FSa) cells, grown either in vitro as primary cultures or in vivo as micro- or macroscopic pulmonary nodules, were determined and compared. FSa cells were separated and synchronized on the basis of size by centrifugal elutriation. Flow microfluorometry (FMF) was used to determine the cell-cycle parameters and the relative synchrony of the separated populations, thus allowing determination of age-dependent cytotoxicity. The colony-forming efficiencies (CFE) of these cells were determined using a lung colony assay. Synchronized cell population of FSa cells, separated by centrifugal elutriation, were injected into recipient animals and exposed 20 min later to a single dose of VCR to determine their age-specific sensitivity. Under these conditions there appeared to be a suggestion of an enhanced killing of cells enriched in the G2 + M phase. However, following prolonged VCR exposure in vitro (e.g., 2.5 micrograms ml-1; 25 ml for 24 h) to primary cultures of FSa cells or in vivo (e.g., 0.25 mg kg-1 per fraction i.p.; 5 fractions in 24 h) to macroscopic pulmonary tumour nodules, elutriated FSa cell populations most enriched with G1 phase cells exhibited the lowest CFE. If under either condition exposed cells were allowed to recover in the absence of VCR for 24 h prior to their removal and separation, FSa cell survival increased in each of the elutriated populations. In contrast, while G1 enriched cell populations from in vitro exposed cultures still exhibited a significant reduction in CFE, no such age-specific response was observed for in vivo exposed macroscopic pulmonary nodules. The stathomokinetic effect of VCR on FSa cells was also readily observed in vitro using FMF analysis (e.g., an increase of from 20 to 38% in the G2 + M phase compartment). While no such effect was observed in vivo using FMF analysis, cluster of mitotic figures were observed. The mitotic indices (MI) of the in vivo exposed FSa cells increased from 2.5 to 8.4%.

Treatment of artificially-induced pulmonary metastases with fractionated doses of vincristine and/or radiation therapy

The cytotoxic effects in vivo of vincristine (VC), radiation, or both modalities in combination on murine fibrosarcoma (FSa) cells grown as pulmonary tumors were determined. Fourteen days following the i.v. injection of viable FSa cells, recipient mice developed between 100 and 150 visible pulmonary nodules. At that time, tumor-bearing animals were exposed to either single or combined modality treatments, as well as single and fractionated dose regimens. Animals were sacrificed 1 hour after the last treatment. Tumor nodules were excised and made into a single cell suspension and separated on the basis of cell size by centrifugal elutriation. Flow microfluorometry (FMF) was used to determine the cell-cycle parameters and the relative synchrony of the separated populations, as well as the percentage contamination by normal diploid cells in each of the tumor cell populations. Known numbers of viable cells from each elutriator fraction were injected into recipient mice to determine their colony-forming efficiency (CFE). Surviving fractions were determined by comparing the CFEs of treated FSa cells from each of the separated elutriator fractions with those of appropriate untreated controls. Following a single dose of VC (1 mg/kg), populations of cells enriched in late S and G2 + M were the most sensitive. However, following the administration of five doses (0.25 mg/kg each) over a 24 hour period, populations of cells most enriched in G1 cells exhibited the lowest percentage of survivors. A single dose of radiation (1000 rad) was most effective in killing S-phase cells. When administered in five fractions (250 rad per fraction), each separated by a 6 hour interval, no phase-specific sensitivity was observed. The combination of both modalities exhibited a marked schedule dependence, with a single dose (1000 rad) of radiation followed by five doses of VC (0.25 mg/kg) being the most effective treatment protocol observed.

Effects of the xanthine oxidase inhibitor allopurinol on the renal clearance of nitroimidazoles

We have investigated the effects of the xanthine oxidase inhibitor allopurinol on the pharmacokinetics of nitroimidazoles in mice and dogs. Studies in mice showed that at a dose of 32 mg/kg given 30-60 min before, allopurinol had little or no effect on the clearance of misonidazole (MISO) or of the more lipophilic analogue Ro 07-0913, but did increase the blood concentrations of the hydrophilic dealkylation product desmethylmisonidazole (DEMIS). In addition, the clearances of administered DEMIS and the even more hydrophilic analogue SR-2508 were markedly reduced. This dose of allopurinol also caused a considerable fall in the clearances of 51Cr-EDTA and 125I-iodohippurate, normally used to measure glomerular filtration rate and effective renal plasma flow respectively. These data are consistent with a model in which allopurinol inhibits the renal clearance of hydrophilic nitroimidazoles. This leads to an increase in the acute toxicity of DEMIS and, to a lesser extent, of MISO. However, lower doses of allopurinol did not change the pharmacokinetics of MISO or DEMIS. A five-day pretreatment regimen (32 mg/kg/day) followed by a 66-76 hr recovery period was also without effect, thus demonstrating that the inhibition was reversible. Investigations in the dog showed that oral doses of 10-20 mg/kg allopurinol caused no change in the clearance of either 51Cr-EDTA or DEMIS.

Noninvasive evaluation of peripheral vascular disease using transcutaneous oxygen tension

Transcutaneous oxygen tension (PtcO2) was used for noninvasive determination of blood supply in 25 patients evaluated for peripheral arterial disease. PtcO2 values were compared with segmental Doppler pressure, pulse volume recording, pulse reappearance time, and angiography in patients being evaluated for wound healing problems, amputations, and peripheral bypass procedures. PtcO2 was measured using a heated (45 degrees C) Clark polarographic electrode to quantitate the oxygen which diffuses from the dermal capillaries to the skin surface. Control PtcO2 values recorded over the chest or shoulder taken while patients were breathing room air were 78 +/- 8 mm Hg. PtcO2 values greater than 50 mm Hg predicted success for levels of amputation and for wound healing without reconstructive procedures; values of 40 mm Hg or less were associated with continued wound problems and complication after amputation. Increased PtcO2 values after vascular reconstruction of the legs predicted improved clinical status on follow-up examinations up to 6 months. PtcO2 predicted the extent of vascular disease as well as the other noninvasive tests and angiography. We conclude that (1) PtcO2 tension is a simple, accurate, noninvasive method to determine the appropriate level of amputation, wound healing potential, and effectiveness of bypass procedures, and (2) PtcO2 values correlate well with angiography and noninvasive evaluations.

Legionella pneumophila in cooling water systems. Report of a survey of cooling towers in London and a pilot trial of selected biocides

Fourteen recirculating cooling water systems were surveyed during the summer, 1981, to see what factors might influence the prevalence of Legionella pneumophila. The effect on the organism of three anti-microbials was studied, each in two systems, by intermittent treatment at two week intervals. L. pneumophila was isolated from six of the 14 cooling systems at the beginning of the trial but by the end was present in ten. An association was found between the presence of the organism and the concentration of dissolved solids, and chlorides and the pH. There also appeared to be associations with exclusion of light and higher water temperatures. Repeated tests on eight untreated systems showed that two were consistently infected, three became and remained infected, one was infected on a single occasion and two were never infected with L. pneumophila. Treatment of a contaminated system, either with a 10 p.p.m mixture of a quaternary ammonium compound and tributyltinoxide or slow release chlorine briquettes (maximum recorded free chlorine level 1.2 p.p.m.), did not eliminated legionellae. Treatment of two infected towers with a chlorinated phenol (100 p.p.m.) eliminated legionellae for at least three days, but after 14 days the organism was again found.

A comparison of mathematical methods for the analysis of DNA histograms obtained by flow cytometry

Twelve methods for analysing FCM-histograms were compared using the same set of data. Some of the histograms that were analysed were simulated by computer and some were taken from experiments. Simulated data were generated assuming synchronously growing cell populations and (i) measurement coefficients of variation (CV) from 2 to 16%; (ii) constant measurement CV or VC's increasing from G1 to G2 phase, and (iii) varying fractions of cells in each phase. Simulated data were also generated assuming synchronous cell populations in which a block in early S phase was applied and released. DNA histograms were measured for L-929 cells at various times after mitotic selection. Labelling indices were also measured for these cells at the same time. The fractions of cells in the G1, S, and (G2 + M) phases were calculated by each analytical method and compared with the actual fractions used for simulation, or in case of experimental data, with autoradiographic results. Generally, all methods yielded reasonably accurate fractions of cells in each phase with relative errors in the range of 10-20%. However, most methods tended to overestimate G1 fractions and underestimate S fractions. In addition, variations in the shape of the S phase distribution often caused considerable errors. Phase fractions were also calculated for histograms of kinetically perturbed populations, simulated as well as experimental. The errors were only slightly larger than for histograms from asynchronously growing cell populations.

Effect of suture technique on arterial anastomotic compliance

To determine the immediate effect of running and interrupted suture on anastomotic compliance, catheters were positioned in both femoral arteries of ten dogs for pressure measurement and introduction of an electromagnetic rheoangiometry loop probe. Changes in the area of the loop allowed simultaneous determination of the static and pulsatile internal diameter of the vessel when the loop was in an externally induced magnetic field. After dynamic diameter compliance (Cd) of the undisturbed femoral arteries was obtained, they were exposed, stripped of their adventitia, and divided. They were subsequently anastomosed with 6-0 polypropylene suture using a running anastomosis for one femoral artery and an interrupted anastomosis for the other; Cd was then measured 1 cm proximal to the anastomoses, at the anastomoses, and 1 cm distal to the anastomoses. The Cd significantly decreased with both running and interrupted anastomoses; running anastomoses showed significantly greater decrease in compliance than did interrupted.

Biological properties of the human colonic adenocarcinoma cell line SW 620 grown as a xenograft in the athymic mouse

The biological and cell kinetic properties of the poorly differentiated human colonic adenocarcinoma cell line SW 620 grown as xenografts in BALB/c athymic mice are described. The SW 620 cells consistently produced tumors when inoculated i.v., i.p., and s.c. The lowest cell inoculum requirements were seen i.p. where 10(7) cells produced a 100% incidence. Intravenous inocula (10(5) to 10(8) cells) produced microscopic lung colonies within 30 days, becoming macroscopic nodules after 60 days. Subcutaneous tumors exhibited a marked Révész effect, using a thromboplastic brain extract which increased both tumor incidence and growth rate. All SW 620 xenografts presented a poorly differentiated morphology with extensive necrotic foci. No metastatic involvement was noted in any murine tissues. No demonstrable levels of carcinoembryonic antigen were present in the sera of animals bearing s.c. xenografts greater than 5.0 cu cm. Early SW 620 xenografts (0.3 to 0.6 cu cm) exhibited a characteristically human cell kinetic profile (Tc congruent to 34 to 43 hr; Ts congruent to 22 hr), with a growth fraction of 30.5% as measured by the primer-available DNA polymerase-index and a high cell loss factor (45%). Among late xenografts (1.1 to 1.6 cu cm), the kinetic events noted were an increase in the Tc, cell loss and, unexpectedly, an increase in the primer-available DNA polymerase index. A colony formation assay was established with the use of mechanical mincing plus collagenase (150 IU/ml; 37 degrees; 30 min), which produced a mean plating efficiency of 33.6 +/- 7.2% (S.E.) for s.c. xenografts (range, 14.6 to 51.0%). The SW 620 xenograft model possesses the biological and cell kinetic profile of many human colonic adenocarcinomas in situ. These properties, coupled with the capacity for large-scale xenograft production, should provide a clinically relevant model for the screening of potential antitumor agents and procedures.

Quiet Zone Within a Seismic Gap near Western Nicaragua: Possible Location of a Future Large Earthquake

A 5700-square-kilometer quiet zone occurs in the midst of the locations of more than 4000 earthquakes off the Pacific coast of Nicaragua. The region is indicated by the seismic gap technique to be a likely location for an earthquake of magnitude larger than 7. The quiet zone has existed since at least 1950; the last large earthquake originating from this area occurred in 1898 and was of magnitude 7.5. A rough estimate indicates that the magnitude of an earthquake rupturing the entire quiet zone could be as large as that of the 1898 event. It is not yet possible to forecast a time frame for the occurrence of such an earthquake in the quiet zone.

Histopathologic observations after short-term implantation of two porous elastomers in dogs

This report describes the effects of pore size and material on soft tissue ingrowth of two medical-grade elastomers. Using the replamineform process, silicone rubber (SR) and bioelectric polyurethane (BEP) were rendered microporous with essentially the same microstructural pore configuration. Implants were prepared in each material having five pore size ranges: 18-25 microns, 30-45 microns, 75-95 microns, 60-120 microns, and 120-180 microns. Implants 1 cm X 1 cm X 1 mm were harvested at 1, 2, 4 and 12 weeks following subcutaneous implantation in mongrel dogs. Ingrowth of the 18-25 microns and 30-45 microns implants in both polymers consisted of histiocytes and dispersed fibrocytic proliferation during the first two weeks. By 12 weeks, the fibrocytic component had increased, but histiocytes remained the principal component of ingrown tissue. In contrast, initial ingrowth of the 75-95 microns, 60-120 microns and 120-180 microns implants showed increased fibrocytic proliferation and minimal histiocytic reaction. By 12 weeks, ingrowth into the larger-pore implants had progressed to broad bands of well organized collagenous stroma. Differences in the rate of tissue ingrowth were found to be related to both material and pore size. Less than 15% of the void spaces were infiltrated by 4 weeks in 18-25 microns and 30-45 microns SR implants, although this increased to approximately 50% by 12 weeks. In contrast, the 3 larger-pore SR implants and all pore sizes in the BEP implants were almost completely ingrown by 4 weeks.

A rapid automated stathmokinetic method for determination of in vitro cell cycle transit times

To provide a rapid method for examining cell cycle dynamics, we utilized continuous exposure of Chinese hamster ovary cells and human colon cancer cells to colcemid to block cycling cells in metaphase, suppressing re-entry into G1. Changes in cell cycle compartment distribution were monitored by DNA flow cytometry. Analysis of the rate of G2 + M compartment accumulation after addition of colcemid permitted calculation of all cycle transit parameters. These compared favorably with data in the same cell lines determined by the fraction of labeled mitoses technique. Serial assessment of DNA flow cytometry after addition of colcemid permits rapid quantitation of cycle traverse rates.

Organ distributions and clearance studies of 99mtechnetium-labeled Corynebacterium parvum in patients with leukemia

The clearance, metabolism and localization of Corynebacterium parvum (C. parvum) labeled with 99mtechnetium (99mTc) given intravenously was studied in various leukemia patients to develop the method and to evaluate reticuloendothelial systems (RES) function. A computer program was utilized to characterize the clearance. C. parvum 0.05 mg was labeled aseptically with 10 mCi of 99mTc with a reducing agent. It was injected intravenously over 5 s and clearance was characterized over the next 60 min. The low dose of C. parvum did not cause any symptoms. The blood or plasma clearance time (t 1/2) was in the range of 0.65 to 1.96 min, in eight patients. By whole body imaging, the distribution of C. parvum was found mainly in the liver, and to a much lesser extent in the spleen, lungs, and bone marrow. Nonparticulate 99mTc (which was not sedimented by centrifugation of blood samples at 3000 rpm for 30 min) appeared rapidly in the blood after i.v. injection accounting for more than half of the radioactivity in a few minutes. In vitro incubation of 99mTc labeled C. parvum with saline, whole blood, serum or leukocytes revealed that the release of free 99mTc resulted from the combined action of serum and leukocytes. The rapid clearance will limit the utility of this preparation in characterizing RES function in man and its modification by disease or therapy.

Use of mini-microaggregated albumin to study reticuloendothelial system (RES) function in C. parvum-treated animals

Mini-microaggregated albumin colloid (particle size less than 80 A) and microaggregated albumin colloid (particle size 500-1000 A) made from human serum albumin were conjugated with 99mtechnetium and used to study reticuloendothelial system (RES) function in animals treated intravenously with C. parvum. The uptake in blood, liver and spleen were studied in untreated mice and in mice at various times after treatment with 150 or 300 micrograms of C. parvum. The blood clearance of these materials was studied in rabbits before and at various times after treatment with 0.5 mg/kg of C. parvum. In mice, 80 A-microaggregated albumin was cleared significantly faster from the blood and localized to a greater extent in the liver and spleen after C. parvum treatment. There was a positive correlation between the increased organ weight induced by C. parvum and the accelerated clearance of 80 A-microaggregated albumin. The 80 A-microaggregated albumin was also cleared more rapidly from the blood of rabbits after C. parvum treatment. These studies suggest that 80 A-microaggregated albumin labeled with 99mTc is a useful tool for study of RES function in animals and because of its relatively long t 1/2 may also be useful for studies of human RES function.

Pacemaker-induced ventricular tachycardia in patients with acute inferior myocardial infarction

We analysed a group of 35 consecutive patients with acute myocardial infarction-23 of the inferior, 12 of the anterior wall-who needed temporary pacing for bradycardiac arrhythmias. We observed in three patients ventricular tachycardias induced by pacemaker stimuli falling onto the vulnerable part of the cardiac cycle due to improper sensing. All three had an inferior myocardial infarction involving the right ventricle. Because the pacemaker electrode in this condition lies in the vicinity of the infarcted myocardium sensing problems occur more frequently and re-entry tachycardias can be triggered more easily. It represents a possible risk of pacemaker treatment in his group of patients who, on the other hand, often need cardiac pacing in the acute phase following the development of transient AV-block.

Cycle-dependent anticancer drug cytotoxicity in mammalian cells synchronized by centrifugal elutriation

The cycle-dependent cytotoxicity of seven chemotherapy agents was compared with the use of subpopulations of Chinese hamster ovary cells separated into the various phases of the cell cycle by centrifugal elutriation. The proportion of cells killed by either beta-cytosine arabinoside or hydroxyurea agreed well with the proportion of S-phase cells in the treated subpopulations. Cell-cycle survival patterns were also determined for bleomycin (BLM), adriamycin (ADR), cis-diamminedichloroplatinum (II) (cis-DDP), Asaley, and Yoshi 864. Three of the agents (cis-DDP, Asaley, and Yoshi 864) had similar cell-cycle survival patterns in that they all preferentially killed cells in the G1 phase. In contrast, BLM preferentially killed cells in G2+M phase, whereas ADR was most cytotoxic to cells in middle to late S-phase. This investigation demonstrated that separation of cultured mammalian cells into the various cell-cycle phases by centrifugal elutriation allows the rapid determination of the phase-dependent cytotoxic effects exerted by chemotherapy agents.

Arterial catheter embolization followed by surgery for large chemodectoma

We report on the first successful preoperative arterial catheter embolization of a large neck chemodectoma followed by its surgical removal. A 21-year-old man presented with a large mass in the right neck diagnosed 5 years previously by biopsy as a chemodectoma. The patient previously had refused therapy. Because of concern over the large size of the mass and increasing difficulty in swallowing, he agreed to undergo therapy. The patient underwent selective occlusion of the occipital and posterior auricular arteries and the thyrocervical trunk using Ivalon sponge emboli injected through a No. 5 Fr Hanafee catheter. A postembolization arteriogram showed 90% occlusion of tumor vascularity and 30% decrease in size of the tumor. This was followed by removal of the tumor surgically. A review of the difficult management of the patient is presented, and implications for future use of the combined procedures are discussed.

Impotence is not always psychogenic. Newer insights into hypothalamic-pituitary-gonadal dysfunction

The concept that impotence is psychogenic in 95% of cases is reconsidered. Screening serum testosterone levels of 105 consecutive patients with impotence showed that 37 patients had previously unsuspected disorders of the hypothalamic-pituitary-gonadal axis. Twenty patients had hypogonadotropic-hypogonadism, seven had hypergonadotropic-hypogonadism, eight had hyperprolactinemia, and two had occult hyperthyroidism. Once the specific defect was defined, appropriate therapy was instituted, and potency was restored in 33 patients. Screening serum testosterone levels is useful in identifying hypothalamic-pituitary-gonadal dysfunction in patients with impotence.

Pharmacokinetic and tumour-penetration properties of the hypoxic cell radiosensitizer desmethylmisonidazole (Ro 05-Ro-9963) in dogs

The hypoxic cell radiosensitizer desmethylmisonidazole (1-(2-nitroimidazol-1-yl)-2,3-propandiol; Ro 05-9963; DEMIS) was administered to 4 dogs at doses of 50 and 200 mg/kg by both oral and i.v. routes. The resulting plasma, cerebrospinal fluid and urinary concentrations were measured by HPLC analysis; various pharmacokinetic parameters were obtained and compared with similar data for the parent compound, misonidazole (MISO), in the dog.Because of its shorter half-life (2·1 h) the total tissue exposure for DEMIS was only half that for a similar dose of MISO, whereas peak plasma concentrations were 60% higher than those for MISO. Cerebrospinal fluid penetration by DEMIS was limited because of the drug's reduced lipophilicity, and the total cerebrospinal-fluid exposure to the drug during the first 5 h after drug administration was about half that previously recorded for MISO.Urinary excretion accounted for 75% of the i.v. dose of unchanged DEMIS, whilst less than 20% of MISO is excreted via this route.DEMIS was also administered to 6 dogs bearing spontaneous tumours at a dose of 150 mg/kg i.v., and the resulting concentrations were recorded in serial biopsies over a 5h period.Mean tumour/plasma ratios ranged between 56 and 90%, and were very similar to those previously observed for MISO in canine tumours. Peak DEMIS tumour concentrations, however, occurred rapidly after dosage (15-20 min) and were as much as twice those for MISO, although they declined rapidly from their initial concentration.We conclude in the light of the reduced tissue exposure, particularly of the nervous tissue, and the improved tumour concentrations, that DEMIS may prove to be a potentially less toxic alternative to MISO.

The penetration of misonidazole into spontaneous canine tumours

The hypoxic cell-radiosensitizing drug misonidazole (1-(2-nitroimidazol-1-yl)-3-methoxypropan -2 -ol, Ro 07-0582, MIS) was administered at a dose of 150 mg/kg i.v. to 6 dogs bearing spontaneous tumours, and the resulting tumour concentrations were measured to HPLC analysis. In 4 dogs it was possible to obtain serial biopsy specimens up to 5 h. With the exception of a brain tumour, the tumour concentrations ranged between 47% and 95% of the plasma concentration, most of the values falling within the range 50--70%. Concentrations in the brain tumour were markedly lower. Barbiturate anaesthesia was necessary for the removal of the serial biopsy specimens, and the effects of sodium pentobarbitone anaesthesia on the pharmacokinetics of MIS were investigated in 2 dogs. After barbiturate anaesthesia peak plasma concontrations were raised and the availability of MIS was increased, although the biological half-life remained unaltered. The metabolism of MIS to the O-demethylated metabolite, Ro 05-9963, was delayed initially. The concentrations of MIS AND Ro 05-9963 in cerebrospinal fluid were also recorded in these dogs; MIS concentrations were found to approach those of the plasma, whereas the metabolite concentrations were considerably lower (0--58% of the plasma concentration).

In vivo comparison of replamineform, Silastic, and bioelectric polyurethane arterial grafts

The replamineform process allows fabrication of microporous prostheses with control of both pore diameter and structural geometry by means of a variety for biomaterials. Tubular prostheses 3 cm long, 6 mm inside diameter, and 1 mm wall thickness were made of Silastic or Bioelectric Polyurethane (BEP) with use of a template of the echinoderm Heterocentrotus mammillatus. Pore diameter of the prosthesis wall was 18 to 25 mu. Light and scanning-electron microscopy of grafts removed between 1 and 32 weeks demonstrated that organization and endothelialization of neointima were similar for both polymers, being complete by 4 to 8 weeks. However, the character of prosthesis wall ingrowth was strikingly different: the microporous lattice of BEP was completely ingrown early, but was apparently fragmented by continued granulomatous inflammation by 32 weeks, while Silastic generated minimal inflammatory response and slower fibrous tissue and capillary ingrowth. Thus, with Silastic and BEP, similarities in neointima organization appeared independent of distinct differences in wall ingrowth. The replamineform process is a unique means of studying surface healing and wall ingrowth of different biomaterials as microporous vascular prostheses in a controlled fashion.

Uniform microporous biomaterials prepared by the Relamineform technique

The Replamineform process provides a technique for fabricating microporous ceramic, metal and polymer biomedical implant materials. A range of pore sizes can be made in the same material, thus allowing independent study of the effect of pore size and biomaterial on incorporation of implants. This new family of biomaterials shows promise for helping to determine the optimum characteristics to enhance tissue regeneration.

"Cytogenetic" studies of spermatids of mice carrying Cattanach's translocation by flow cytometry

The DNA content of spermatids of mice carrying Cattanach's translocation has been measured with high precision by flow cytometry. The observation that the two peaks of DNA content in the haploid region of the DNA histograms represent X- and Y-bearing spermatids was tested and confirmed. Using flow cytometry, the difference in DNA content between the X and Y chromosomes in these mice was measured to be 5.2 +/- 0.1% of the total haploid genome as compared to 3.4 +/- 0.1% in normal mice. These results demonstrated the precision of flow cytometry for cytogenetic studies. Additional information on spermatogenesis in mice bearing Cattanach's translocation was obtained and showed a gradual loss of cells during spermatogenesis in those bearing the balanced form of the translocation.

T-lymphocyte heterogeneity in the rat: separation of functional subpopulations using a monoclonal antibody

W3/25 antibody is the monoclonal product of a hybrid cell resulting from the fusion of a mouse myeloma cell line with spleen cells from a mouse immunized with rat thymocytes. Pure clones have been derived, and segregants free of parental myeloma chains have been isolated. Previous studies have shown that this antibody recognizes a subpopulation of T cells among rat thoracic duct lymphocytes. In the work reported here, three T-cell functions were assayed after separating rat thoracic duct lymphocytes on the fluorescence-activated cell sorter on the basis of labeling with W3/25 antibody. Two of the functional activities appeared to be completely segregated by this procedure. Thus, helper cell activity for an anti-hapten plaque-forming cell response was confined to the labeled population, whereas the allogeneic suppressive effect produced in a parental vector F1 adoptive transfer was mediated by cells in the unlabeled fraction. The third function, graft-versus-host activity, was almost entirely contained within the labeled subpopulation. It is concluded that the antigenic determinant recognized by the monoclonal antibody W3/25 is a differentiation marker for T-cell functional subpopulations.