Chemotherapy without irradiation--a novel approach for newly diagnosed CNS germ cell tumors: results of an international cooperative trial. The First International Central Nervous System Germ Cell Tumor Study

PURPOSE

Radiation therapy for CNS germ cell tumors (GCT) is commonly associated with neurologic sequelae. We designed a therapeutic trial to determine whether irradiation could be avoided.

PATIENTS AND METHODS

Patients received four cycles of carboplatin, etoposide, and bleomycin. Those with a complete response (CR) received two further cycles; others received two cycles intensified by cyclophosphamide.

RESULTS

Seventy-one patients were enrolled (45 with germinoma and 26 with nongerminomatous GCT [NGGCT]). Sixty-eight were assessable for response. Thirty-nine of 68 (57%) achieved a CR within four cycles. Of 29 patients with less than a CR, 16 achieved CR with intensified chemotherapy or second surgery. Overall, 55 of 71 (78%) achieved a CR without irradiation. The CR rate was 84% for germinomas and 78% for NGGCT. With a median follow-up duration of 31 months, 28 of 71 patients were alive without relapse or progression. Thirty-five showed tumor recurrence (n = 28) or progression (n = 7) at a median of 13 months. Twenty-six of 28 patients (93%) who recurred following remission underwent successful salvage therapy. Pathology was the only variable predictive of survival. The probability of surviving 2 years was .84 for germinoma patients and .62 for NGGCT. Seven of 71 patients died of toxicity associated with study chemotherapy.

CONCLUSION

Forty-one percent of surviving patients and 50% of all patients were treated successfully with chemotherapy only without irradiation. Chemotherapy-only regimens for CNS GCT, although encouraging, should continue to be used only in the setting of formal clinical trials.

Removal of fibromyomas by laparoscopic surgery after preoperative GnRH analogue--an alternative to abdominal hysterectomy or myomectomy

Nineteen patients with fibromyomas who had been recommended to have a hysterectomy or abdominal myomectomy were referred as they wished to avoid a hysterectomy (14) or laparotomy incision for a myomectomy (5). Following administration of the GnRH analogue goserelin, laparoscopic surgery was performed on all these patients. Hysterectomy was avoided in all but 1 of the 14 patients and laparotomy myomectomy was avoided in 4 of the 5 patients recommended to have these procedures. The combination of a GnRH analogue and laparoscopic-based surgery may be an acceptable alternative to both laparotomy myomectomy and hysterectomy in women with fibromyomas requiring surgery.

The role of monoamine metabolism in oxidative glutamate toxicity

Glutamate kills neuronal cells by either a receptor-mediated pathway or the inhibition of cystine uptake, the "oxidative pathway." Antioxidants can block cell death initiated by either pathway, suggesting that toxicity is dependent on the production of free radicals. We provide evidence that in a neuronal cell line, glutamate toxicity via the oxidative pathway requires monoamine metabolism as a source of free radicals. Glutamate toxicity is inhibited by monoamine oxidase (MAO) type-A-specific inhibitors, but only at concentrations much higher than those required to inhibit classical type-A MAO. Toxicity is not inhibited by MAO type-B-specific inhibitors at any concentration. Furthermore, treatment of cells with agents that block monoamine uptake inhibits glutamate toxicity. These results suggest that an enzyme distinct from MAO is involved in monoamine metabolism and demonstrate a relationship between glutamate toxicity and monoamine metabolism. These data also have implications for the understanding and treatment of neurodegenerative disorders in which glutamate toxicity is thought to be involved.

Underutilization of laparoscopic oophorectomy

The objective of this study was to compare the use and effectiveness of laparoscopic and laparotomy oophorectomy in 3 hospitals in Melbourne. A retrospective analysis was made of medical records of 140 patients having laparoscopic or laparotomy oophorectomy in the Mercy Hospital for Women (41), Monash Medical Centre (37), and Cliveden Hill Private Hospital (62). Both public hospitals used the laparoscopic procedure, 12% and 22% respectively, less often than the private hospital, 94%. The average number of hospital days for procedures completed by laparoscopy was 1.3 and for laparotomy 6.9. Fourteen percent of laparoscopic procedures were converted to laparotomy. Adjusting for this the average hospital stay was 1.6 days of procedures started laparoscopically. Assuming 1,000 oophorectomies are performed each year in Australia of which 80% could be performed laparoscopically, there may be cost savings to health care providers of over $1.5 million. Laparoscopic oophorectomy is a safe, effective and cost-efficient method of removing the ovary and gynaecologists should be encouraged to learn and perform this procedure.

Peritoneal surgery in the treatment of endometriosis--excision or thermal ablation?

Twenty patients with Stage 2 to 4 endometriosis were referred to an Endometriosis Clinic with an average of 3.4 previous medical and surgical treatments. All were treated by peritoneal excision. Follow-up was for 9-36 months and 14 had a further laparoscopy. Seventeen of 20 patients are free of symptoms. In 1 patient recurrence occurred in a separate site and in 2 there were lesions close to the original lesion in the pouch of Douglas and bladder wall. In addition, 1 of the 14 patients having further laparoscopy had mild adhesions. The satisfactory results of the study suggest that a controlled trial comparing peritoneal excision and thermal ablation is worthwhile. There are considerable theoretical advantages in using peritoneal excision rather than peritoneal thermal ablation.

Routine use of ureteric catheters at laparoscopic hysterectomy may cause unnecessary complications

STUDY OBJECTIVE

To test the use of ureteric catheters in preventing ureteric trauma during laparoscopic hysterectomy.

DESIGN

Prospective study of 492 consecutive women.

SETTING

Pelosi Women's Medical Center, New Jersey, and Cliveden Hill Private Hospital, Melbourne, Australia.

PATIENTS

Four hundred ninety-two consecutive women.

INTERVENTIONS

Laparoscopic hysterectomy was performed in all women. Because of the reported increased risk of ureteric trauma during laparoscopic hysterectomy, we passed ureteric catheters in 92 such procedures and ceased the practice with the last 400 when further reports suggested lack of increased risk.

MEASUREMENTS AND MAIN RESULTS

Oliguria and anuria occurred in 7 of 92 patients having ureteric catheterization. No ureteric trauma occurred in 400 patients without ureteric catheterization. The injury rate in this series was significantly lower than in three other series of abdominal hysterectomy.

CONCLUSIONS

As long as surgical techniques incorporate various procedures to avoid ureteric injury, routine ureteric catheterization during laparoscopic hysterectomy is not indicated and may result in unnecessary complications.

Copper and calcium binding motifs in the extracellular domains of fibroblast growth factor receptors

High affinity fibroblast growth factor (FGF) receptors contain a cluster of acidic amino acids in their extracellular domains that is reminiscent of the calcium binding domains of some cell adhesion molecules. Based on this observation, we used a calcium blotting technique to show that FGFR-1 binds calcium and that calcium binding is not observed in a mutagenized form of the receptor that lacks the acidic box region. The acidic box also binds other divalent cations, including copper. This latter interaction appears unique since the binding of copper to FGFR-1 mediates the binding of the receptor to immobilized heparin. While this observation may help explain the angiogenic properties of copper, divalent cation binding to FGF receptors may also mediate the interaction between FGF receptors, cell adhesion molecules and other proteoglycan components of the extracellular matrix.

The role of calmodulin in the gravitropic response of the Arabidopsis thaliana agr-3 mutant

Calmodulin, a primary plant calcium receptor, is known to be intimately involved with gravitropic sensing and transduction. Using the calmodulin-binding inhibitors trifluoperazine, W7 and calmidazolium, gravitropic curvature of Arabidopsis thaliana (L.) Heynh, ecotype Landsberg, roots was separable into two phases. Phase I was detected at very low concentrations (0.01 microM) of trifluoperazine and calmidazolium, did not involve growth changes, accounted for about half the total curvature of the root and may represent the specific contribution of the cap to gravity sensing. Phase II commenced around 1.0 microM and involved inhibition of both growth and curvature. The agr-3 mutant exhibited a reduced gravitropic response and was found to lack phase I curvature, suggesting that the mutation alters either use or expression of calmodulin. The sequences of wild-type and agr-3 calmodulin (CaM-1) cDNAs, which are root specific were completely determined and found to be identical. Upon gravitropic stimulation, wild-type Arabidopsis seedlings increased calmodulin mRNA levels by threefold in 0.5 h. On the other hand, gravitropic stimulation of agr-3 decreased calmodulin mRNA accumulation. The possible basis of the two phases of curvature is discussed and it is concluded that agr-3 has a lesion located in a general gravity transmission sequence, present in many root cells, which involves calmodulin mRNA accumulation.

Laparoscopic minilaparotomy hysterectomy

A laparoscopic minilaparotomy hysterectomy technique is described. An abdominal elevator allowed the use of an open 2 cm port in the lower abdomen to introduce the finger and instruments used for laparotomy. The technique was developed in 3 patients with moderate to severe endometriosis. The second and third operations were quicker than could be expected by laparovaginal surgery. The use of laparotomy instruments and techniques make the technique easier to learn, cheaper than techniques using disposable products and has the potential to be faster and possibly safer than current techniques. It retains the advantage of laparoscopy surgery, reduced postoperative pain, small incisions and early discharge from hospital.

Excision of endometriosis in the pouch of Douglas by combined laparovaginal surgery using the Maher abdominal elevator

Twenty-one patients with stage 3 or 4 endometriosis in the pouch of Douglas had combined laparovaginal surgery using the Maher abdominal wall elevator. Opening the pouch of Douglas at the beginning of the operation allowed the combined surgery. Instruments were introduced through both the vagina and accessory laparoscopic incision. And a finger was placed in the vagina to palpate and detect abnormal tissue and assist in blunt dissection. The extent of pathologic tissue in the pouch of Douglas was easily identified. This approach allowed flexibility in maximizing the optimum route, vaginal or laparoscopic, to remove the uterus, and facilitated rectal surgery. The alternatives of laparoscopic and laparotomy surgery have limitations compared with combined laparovaginal surgery, particularly deep in the pelvic cavity.

Biopsy diagnosis and conservative surgical treatment of adenomyosis

STUDY OBJECTIVE

To diagnose adenomyosis by vaginal ultrasound and percutaneous or transcervical myometrial biopsy, and use the results to choose treatment and assess prognosis.

DESIGN

Evaluation of 31 consecutive women referred by other physicians.

SETTING

A private gynecologic practice.

PATIENTS

The women had menstrual symptoms that had not responded to medical treatment or uterine curettage.

INTERVENTIONS

Myometrial diagnosis was made by percutaneous ultrasound-guided needle biopsy, by transcervical electrosurgical loop biopsy at the time of endometrial resection, or by needle biopsy at the time of laparoscopy or laparotomy. Endometrial resection was performed in 15 patients, laparoscopic myometrial reduction in 7, and excision of adenomyotic myometrium or localized adenomyoma in 8.

MEASUREMENTS AND MAIN RESULTS

Cure was defined as relief of menorrhagia and dysmenorrhea. Endometrial resection cured menorrhagia in 12 of 15 patients but dysmenorrhea in only 3 of 8; myometrial excision cured 7 of 8, and myometrial reduction 4 of 7 women.

CONCLUSIONS

Vaginal ultrasound combined with transabdominal or transcervical myometrial biopsy established the diagnosis of adenomyosis in all patients. Endometrial resection and myometrial reduction or excision reduced the need for hysterectomy to 30% in these women.

Protein kinase C activation inhibits glutamate-induced cytotoxicity in a neuronal cell line

A neuronal cell line, HT-22, is sensitive to glutamate cytotoxicity via a non-receptor mediated oxidative pathway. 12-O-tetradecanoylphorbol-13-acetate (TPA), an activator of protein kinase C, blocks this glutamate-induced cell death. Down-regulation of protein kinase C eliminates the protection against glutamate cytotoxicity afforded by TPA. The data suggest that protein kinase C activation blocks an early step in the cytotoxic pathway.

Laparovaginal hysterectomy

The technique and complications of 141 patients having laparovaginal hysterectomy in private practice are reported. Abdominal hysterectomy was avoided in the 110 patients having preliminary laparoscopic surgery for pelvic disease, ovarian removal, or a uterus larger than 12cm. Postoperative morbidity included pulmonary embolus (3), vesicovaginal fistula (2) and pelvic haematoma (4). The frequency of complications was less than that reported after abdominal or vaginal hysterectomy. The surgical technique changed during the series; the operative care of the bladder and ureter requires particular attention. A larger number of patients in a variety of centres require study before the laparoscopic procedure can be determined to be as safe as abdominal or vaginal hysterectomy. The laparoscopic procedure has the potential to replace the majority of abdominal hysterectomies.

Laparoscopic removal of endometriosis in the pouch of Douglas

Twenty-six patients with endometriosis in the pouch of Douglas were treated by laparoscopic excisional surgery; previous medical and surgical therapy had failed in 24 of them. Endometriosis in the pouch of Douglas occurred infrequently in association with bladder or ovarian endometriosis. Coital and rectal pain were markedly reduced or cured 6 months after surgery in all except 2 patients. Laparoscopic surgical excision of endometriosis is indicated when drug or other surgical treatments fail and may avoid the need for hysterectomy in some patients.

Biopsy diagnosis and conservative surgical treatment of adenomyosis

Fifteen patients with dysmenorrhoea and menorrhagia refractory to medical treatment were referred for surgical treatment. Pre-operative diagnosis of adenomyosis was suggested by vaginal ultrasound in 13 patients and was confirmed pre-operatively by myometrial biopsy in 5 and by transcervical myometrial biopsy at the time of endometrial resection in 7. Conservative surgery included endometrial resection (7), myometrial reduction by electrocautery (4), and myometrial excision (3). Marked improvement occurred in 4 of 7 patients after endometrial resection, 3 of 4 after myometrial reduction, and all of 3 having myometrial excision. Diagnosis of adenomyosis is improved by use of vaginal ultrasound and percutaneous or transcervical myometrial biopsy. Conservative surgical procedures including endometrial resection and myometrial reduction or excision may reduce the need for hysterectomy in the presence of adenomyosis.

Laparoscopic culdotomy

Laparoscopic culdotomy has been performed in 32 patients. The indications for the procedure included the removal of organs or tissue excised by operative laparoscopy, excision of vaginal endometriosis involving the pouch of Douglas and drainage of a pelvic haematoma. The surgical technique is described and no complications resulted from this technique. Laparoscopic culdotomy has advantages for the removal of lumps exceeding 1 cm, and for the drainage of a pelvic haematoma or pelvic abscess. It is also an integral step in the removal of infiltrating endometriotic lesions in the pouch of Douglas which are attached to the vagina.

Laparoscopic adnexectomy--indications, technique and results

Laparoscopic adnexectomy was performed successfully in 38 patients in whom the procedure was attempted. Failure may result from inexperience of the surgeon or when preliminary dissection near bowel suggests trauma is likely. The duration of the operation was between 15 and 105 minutes, blood loss was minimal and all but 2 patients were discharged within 24 hours of surgery. Pain was relieved in 33 of 35 patients in whom this was the dominant symptom. In 1 patient a small ovarian remnant implanted on the bladder was removed at subsequent laparoscopy. Preliminary experience of this procedure suggest it may be preferable to laparotomy because of the reduced risk of wound complications, pain, time in hospital and duration of convalescence.

Growth factors and vitamin E modify neuronal glutamate toxicity

The sympathetic nerve cell line PC-12 is killed by glutamate in a concentration-dependent manner. Although glycine and the deletion of magnesium weakly potentiate glutamate toxicity and PC-12 cells express N-methyl-D-aspartate-receptor mRNA, most toxicity is mediated by means of a mechanism independent of typical N-methyl-D-aspartate receptors. Glutamate toxicity is, however, greatly enhanced by prior exposure to nerve growth factor or basic fibroblast growth factor. Glutamate killing is blocked by epidermal growth factor and, to a lesser extent, by vitamin E. These observations show that synergistic interactions between growth factors and excitotoxic amino acids may play critical roles in the developing nervous system and that antioxidants attenuate this toxicity.

Minimally invasive gynaecological surgery

Most gynaecological operations can now be performed laparoscopically. The results for patients are a reduction in pain, less time spent in hospital and in convalescence and cost savings. For some procedures the risk of infection and adhesion formation is also reduced. This pelviscopic surgery requires extra training in special surgical skills to overcome the risks that include incomplete surgery resulting from poor access to a pelvic lesion or trauma to organs as a result of poor technique. Most patients with ectopic pregnancy, pelvic adhesions, endometriosis, ovarian cysts and fibromyomata can be treated by this advanced laparoscopic surgery. Hysteroscopic endometrial resection can replace hysterectomy for most patients with menorrhagia who have a normal size uterus.

Diagnosis and surgical management of endometriomas

Fifty two patients with endometriomas greater than 1 cm were treated by surgical excision either with or without ovarian closure. Diagnosis is reliable when clinical features of the pain, vaginal ultrasound, and laparoscopy, including ovarian mobilization and needling, are considered. Fifty of 52 patients were free of pain after 1 year and 26 (50%) became pregnant within 1 year. A second laparoscopy is justified if pain persists or pregnancy does not occur. Adhesive disease was the most common complication (40%), and persistent or recurrent endometriosis occurred in 15%. Surgery by laparoscopy with drainage and excision of the endometrioma without ovarian sutures may be more effective than excision of the endometrioma and ovarian suture.

Cytomegalovirus infection in cardiac transplant recipients associated with chronic T cell subset ratio inversion with expansion of a Leu-7+ TS-C+ subset

Lymphocyte subsets were analysed in 18 patients during the first 3 years after cardiac transplantation. The patients received Cyclosporin A and prednisolone for maintenance immunosuppression. Serological evidence of active cytomegalovirus (CMV) infection was found in 13 cases (72%), and in 12 of these an inversion usually of the T helper/T suppressor-cytotoxic ratio (TH/TS-C) was detected. T subset inversion usually preceded the diagnostic rise in CMV antibody titre. In 69% of patients with CMV the TH/TS-C ratio remained inverted throughout follow-up (245-951 days). Persistent T subset inversion was not found in all five patients who lacked serological evidence of active CMV. Chronic inversion consisted of an average increase in TS-C of 152% and an average decline in TH cells of 31% as compared to CMV negative patients. The proportion of lymphoid cells reacting with a phenotypic marker for natural killer (NK) cells (Leu-7) was increased by 83%. These alterations were also reflected in the absolute numbers of cells with these markers. Two-colour immunofluorescence analysis revealed that the expanded TS-C population present during chronic inversion was predominantly Leu-7+. As TS-C+ Leu-7+ cells in healthy persons may be hyporesponsive NK cells, a sustained increase in this cell type in allograft recipients could further reduce immunocompetence, thereby predisposing to superinfection or malignancy.

'Rejection or infection' predictive value of T-cell subject ratio, before and after heart transplantation

Peripheral T-cell subsets were monitored in ten heart and two heart-lung recipients pre- and up to one year post-operatively. Prior to transplantation four patients had T-helper/T-cytotoxic suppressor ratios (TH/TS-C) above the range for normal healthy controls and all required treatment for rejection episodes, as compared with three of eight patients whose pre-transplantation ratios were within the normal range. No patient with high TH/TS-C ratios developed cytomegalovirus infection as compared with all of the eight patients with normal ratios. Post-transplantation cytomegalovirus infection was the major cause of alterations in TH/TS-C ratios. T-cell subset inversion always preceded the diagnostic rise in cytomegalovirus antibody titre in both primary and secondary cytomegalovirus infections. Inversion was also noted with Pneumocystis carinii infection. Reversal of the TH/TS-C ratio was due to a major increase in the absolute numbers of TS-C cells and was usually followed by a rise in the number of cells expressing a natural killer cell phenotypic marker (Leu-7). All patients with primary cytomegalovirus and two of four cases with secondary cytomegalovirus retained inversion throughout follow-up and showed significantly increased numbers of TS-C and Leu-7 bearing cells. However, the absolute numbers of TH fell by 200 days after transplantation in all patients irrespective of their TH/TS-C ratio. Although TH/TS-C ratio inversion was a predictor of cytomegalovirus infection, no association was found between changes in T-cell subsets after transplantation and rejection episodes.

A Comprehensive Preseason Fitness Evaluation for Professional Baseball Players

In brief: Preseason health and fitness evaluations were performed on 40 professional baseball players to assess level of conditioning, potential for injury, and health-related lifestyle habits. Group means for coronary risk profile, muscular endurance, flexibility, and maximum aerobic capacity were normal, but screening identified many players with problems or potential problems. Test findings resulted in at least one training or life-style recommendation in every player tested. This information provides a comprehensive physiological profile of one professional baseball team. Further research is needed to define sport-specific testing for the professional baseball player.

Does indomethacin cause extension of intracranial hemorrhages: a preliminary study

Thirty-six infants who had an intracranial hemorrhage (diagnosed by cranial ultrasound) within four days after delivery (mean age 2.4 +/- 0.9 (SD) days), were reexamined at three- to seven-day intervals for extension of their intracranial hemorrhage. Seventeen infants had a patent ductus arteriosus and were treated with indomethacin after the initial intracranial hemorrhage was diagnosed. The age for starting indomethacin was 3.8 +/- 1.1 days. Nineteen infants did not have a patent ductus arteriosus and did not receive indomethacin. Both the indomethacin-treated and nontreated groups were similar in birth weight, gestational age, Apgar scores, gender, incidence of respiratory distress, as well as the location and the degree of hemorrhage in the initial scans. Only one of 17 (6%) infants who received indomethacin v tow of 19 (11%) infants who did not receive it, had extension of their initial intracranial hemorrhage. Although indomethacin may alter platelet function, it does not appear to cause extension of a preexisting intracranial hemorrhage.

Structural changes in membranes produced by the binding of small amphipathic molecules

In their interactions with membranes, amphipathic small molecules exhibit detergent-like properties. At sufficiently high concentrations (above their critical micelle concentrations, if they form micelles), they substantially dissolve membranes. At lower concentrations, between maximally antihemolytic and lytic, we show here that the amphipaths significantly perturb membrane structure. Each of six small-molecule amphipaths was shown by hygroscopic desorption filtration to induce the extraction of small but significant amounts of membrane components, partly in the form of vesicular fragments, from red blood cell membranes. These extracts were enriched in the lipid to protein ratio as compared to the intact membrane, and the protein composition was highly unrepresentative. A similar set of extractions from sarcoplasmic reticulum membranes was induced by the six amphipaths. We conclude that small-molecule amphipaths, at concentrations lower than lytic, promote gross redistributions of components in the plane of a membrane that result in the observed extractions.

A 200-kd protein isolated from the fascia adherens membrane domains of chicken cardiac muscle cells is detected immunologically in fibroblast focal adhesions

On the premise that the fascia adherens of cardiac muscle cell intercalated disk membranes is a structure that is closely homologous to the focal adhesions formed by fibroblasts, a fascia adherens preparation was isolated from chicken cardiac muscle, and was analyzed for its protein composition. A prominent 200-kilodalton (kd) protein was purified from the fascia preparation and shown to be antigenically unrelated to several previously characterized cytoskeletal proteins, including cardiac myosin and vinculin. With monospecific antibodies to the 200-kd protein, an identical or closely similar intracellular protein was shown to be associated with the focal adhesion plaques of fibroblasts.

Analysis of lectin-specific cell surface glycoprotein on neuroblastoma cells

The binding sites for the lectins wheat germ agglutinin, Ricinus communis agglutinin and concanavalin A on mouse neuroblastoma cell membranes were identified using SDS-gel electrophoresis in combination with fluorescent lectins. Ricinus communis agglutinin and wheat germ agglutinin were found to bind almost exclusively to a single polypeptide with an apparent molecular weight of 30 000. Concanavalin A labeled over 20 different polypeptides, most with molecular weights greater than 50 000. However, when the neuroblastoma cells were treated with concanavalin A so as to internalize all the concanavalin A binding sites visible at the level of the fluorescent microscope and the purified plasma membranes analyzed for their concanavalin A binding polypeptides, only four of the 20 glycopolypeptides were missing or significantly reduced in amount. Thus, these four high molecular weight concanavalin A-binding polypeptides appear to be the major cell surface receptors for concanavalin A. Binding studies with iodinated concanavalin A indicated that these polypeptides represented the high affinity concanavalin A binding sites (Kd = 2 . 10(-7) M). Low affinity concanavalin A binding sites were present on the cell surface after internalization of high affinity concanavalin A binding sites.

Differences in the redistribution of concanavalin A and wheat germ agglutinin binding sites on mouse neuroblastoma cells

Concanavalin A (Con A), wheat germ agglutinin (WGA), and Ricinus communis agglutinin (RCA) bound with either 125I, fluorescent dyes, or fluorescent polymeric microspheres were used to quantitate and visualize the distribution of lectin binding sites on mouse neuroblastoma cells. As viewed by fluorescent light and scanning electron microscopy, over 10(7) binding sites for Con A, WGA, and RCA appeared to be distributed randomly over the surface of differentiated and undifferentiated cells. An energy-dependent redistribution of labeled sites into a central spot occurred when the cells were labeled with a saturating dose of fluorescent lectin and maintained at 37 degrees C for 60 min. Reversible labeling using appropriate saccharide inhibitors indicated that the labeled sites had undergone endocytosis by the cell. A difference in the mode of redistribution of WGA or RCA and Con A binding sites was observed in double labeling experiments. When less than 10% of the WGA or RCA lectin binding sites were labeled, only these labeled sites appeared to be removed from the cell surface. In contrast, when less than 10% of the Con A sites were labeled, both labeled and unlabeled Con A binding sites were removed from the cell surface. Cytochalasin B uncoupled the coordinate redistribution of labeled and unlabeled Con A sites, suggesting the involvement of microfilaments. Finally, double labeling experiments employing fluorescein-tagged Con A and rhodamine-tagged WGA indicate that most Con A and WGA binding sites reside on different membrane components and redistribute independenty of each other.

Alterations in chromatin of cells infected with RNA tumor viruses

Chromatins were isolated from murine leukemia or sarcoma virus infected lymphocyte-like TB cells and compared by immunological and biochemical methods. Chromatin from virus infected cells did not fix complement as well as uninfected cell chromatin suggesting that conformational changes had occurred in chromatin from virus infected cells. This alteration was detected within 24 hours after infection. Infected cell chromatins, examined by electrophoretic methods after radiolabeling displayed alterations in nonhistone proteins, whereas the histones appeared unaltered. The non-histones were synthesized in greater amounts in infected compared to normal cells, particularly a 60,000 D protein, while the amount of histone did not vary. The above changes should not have been due to cell growth or cycle variations, for the cells had similar growth rates and were harvested from the same stage of cell confluency during exponential growth to ensure uniformity of culture conditions.

A change in the internal affinity of LK goat red-cell sodium pumps induced by high pH

The K inhibition of ouabain-sensitive ATPase activity of LK goat red cell membranes is greatly reduced at high pH. This effect is reversible, and specific, since the apparent affinities for ATP, ouabain or external K do not alter. Anti-L-treated membranes show a similar alkali-induced affinity change, but have a lower pH optimum.

Stoichiometry and accessibility of histone 3 sulfhydryl groups in chromatin subunits

The accessibility of the sulfhydrl groups of histone 3(H3) in chromatin subunit particles has been investigated by reaction with p-hydroxymercuribenzoate. The resuls indicate that the carboxy-terminal regions of H3 are buried in the native particle, and suggest the presence of 2 mol of H3 per chromatin monomer.