Comparison of methods for the Fmoc solid-phase synthesis and cleavage of a peptide containing both tryptophan and arginine

A major side reaction which can occur during the synthesis of Trp-containing peptides is modification of the Trp indole by reactive carbonium ion species released during acidolytic cleavage. [Asn2,Trp4]Dynorphin A-(1-13), a sequence which is very susceptible to Trp modification, was chosen as a model peptide to compare the effectiveness of various methods proposed to minimize Trp modification during Fmoc solid-phase synthesis. The peptide was synthesized with the side chain of Trp unprotected and cleaved by Reagent K [82.5% trifluoroacetic acid (TFA)/5% phenol/5% water/5% thioanisole/2.5% ethanedithiol (EDT)] [King, D.S. et al. (1990) Int. J. Peptide Protein Res. 36, 255-266], Reagent R [90% TFA/5% thioanisole/3% EDT/2% anisole] [Albericio, F. et al. (1990) J. Org. Chem. 55, 3730-3743], TFA containing 20% EDT and 4% water [Riniker, B. & Hartmann, A. (1990) in Peptides: Chemistry, Structure, and Biology (Rivier, J.E. & Marshall, G.R., eds.), pp. 950-952, Escom, Leiden], and TFA containing trialkylsilane, MeOH, and ethylmethyl sulfide [Chan, W.C. & Bycroft, B.W. (1992) in Peptides: Chemistry, Structure, and Biology, Op. cit., pp. 613-614]. Cleavage with Reagent K, Reagent R and TFA containing 20% EDT and 4% water yielded similar results; in addition to the desired peptide, the crude product contained 22-30% of a side product which appeared to result from Trp modification by a Pmc group. Cleavage with the trialkylsilane-containing mixture gave the lowest recovery of the desired peptide and the highest levels of Pmc-containing peptides.(ABSTRACT TRUNCATED AT 250 WORDS)

Urodynamic evaluation in pediatric neurogenic bladder

Urodynamic evaluation in pediatric neurogenic bladder is prerequisite for accurate prediction of prognosis and selection of appropriate treatment modality. We classified normal, hyperreflexic and areflexic bladders by cystometry. Hyperreflexic bladder was subdivided into two groups with or without detrusor sphincter dyssynergia and areflexic bladder into low pressure and high pressure. Among 36 patients with myelodysplasia on whom we performed a videourodynamic study vesicoureteral reflux was found in three of 7 patients with hyperreflexia with detrusor sphincter dyssynergia, two of 6 patients with hyperreflexia without detrusor sphincter dyssynergia and five of 10 patients with areflexia with high pressure. Low pressure areflexic bladder didn't show vesicoureteral reflux. When we evaluated 39 pediatric neurogenic bladder patients with a mean 25.5 follow-up months period, upper tract deterioration was improved and normal findings persisted in all the compliant patients to treatment. In the noncompliant group initial abnormal upper tract findings persisted or aggravated, especially in hyperreflexic bladder with dyssynergia and high pressure areflexic bladder. One of the three hyperreflexic bladders with dyssynergia and two of six high pressure areflexic bladders received augmented cystoplasty. These data show that urodynamic evaluation in pediatric neurogenic bladder provides excellent criteria for selecting high risk groups in pediatric neurogenic bladder.

Aspergillus fumigatus antigen induced eosinophilia in mice is abrogated by anti-IL-5 antibody

A murine model of allergic bronchopulmonary aspergillosis (ABPA), developed by exposure to Aspergillus fumigatus antigens, demonstrated eosinophilia of peripheral blood (PB), bone marrow (BM), and lung. The eosinophilia was abrogated by monoclonal anti-interleukin-5 (IL-5) antibody (TRFK-5) and not by an isotype control antibody (GL 113). Eosinophils in PB were enumerated from stained smears and their relative increase or decrease in cells from BM and lung was determined by an eosinophil peroxidase (EPO) assay (measured in optical density). Intraperitoneal injection of TRFK-5 in mice exposed to A. fumigatus antigen produced a significant reduction in eosinophils (PB 6.6 +/- 1.14% vs. 3.8 +/- 0.8%, P < .01) and EPO production in BM (0.935 +/- 0.03 vs. 0.615 +/- 0.02, P < .001). A similar reduction in EPO production in the lung (0.691 +/- 0.12 vs. 0.495 +/- 0.05, not significant) was also reflected in the histopathology for the different groups of mice. These findings confirming the role of IL-5 in eosinophilia, although not surprising, are significant in elucidating the immunopathogenesis of ABPA in the murine model. We conclude that in this model, eosinophilia may be due largely to the Th2 cytokine -IL-5 induced by A. fumigatus antigens.

Cultural and noncultural factors as determinants of caregiver burden for the impaired elderly in South Korea

This study investigated the determining variables of caregiver burden in caring for impaired older relatives in South Korea. Economic factors, daily caregiving hours, and caregiver's health status emerged as the most important determinants of caregiver burden in Korea. Though not a powerful predictor, caregivers' congruency with the traditional caregiver selection norms remained a statistically significant predictor of certain dimensions of caregiver burden.

Experimental results using nafamostat mesilate as anticoagulant during extracorporeal lung assist for 24 hours in dogs

We report on the experimental application of nafamostat mesilate (NM, 6-amidino-2-naphthyl p-guanidinobenzoate dimethanesulfonate, FUT), a new anticoagulant, to extracorporeal lung assist (ECLA) with an artificial membrane lung. Venovenous ECLA, from the jugular vein to the femoral vein, was performed with a hollow-fiber membrane lung at a blood flow rate of approximate 82 ml kg-1 min-1 for 24 h in 7 dogs under anesthesia and hypoventilation. Heparin (10 U ml-1 in a priming lactated Ringer solution of 140 ml, and 200 U kg-1) was administered before blood access cannulation. After start of ECLA, however, no heparin was used, and nafamostat mesilate was continuously infused into the drainage line of the bypass circuit to control activated coagulation time (ACT) at about 150 to 200 s. To maintain the prolonged ACT, 8.0 +/- 1.7 mg kg-1 h-1 of NM was required. Arterial blood pressure and pulse rate decreased significantly. Though fibrin monomer test revealed hypercoagulability after 6 h of ECLA, platelet counts did not significantly decrease. Total blood loss remained less than 40 g. The artificial membrane lung sustained a good gas exchange and low flow resistance throughout ECLA. Macroscopic examination revealed small spotty thrombi in the artificial lung but no major pathologic changes of the visceral organs in the all dogs at autopsy. High-dose NM administration could control blood coagulation and decrease blood loss during ECLA for 24 h without deterioration of the artificial lung and systemic complication other than mild hypotension and bradycardia.

[A patient with severe ventricular tachycardia who was saved by prolonged extracorporeal lung and heart assist]

A 47-y-o man had been suffering from cardiac failure due to refractory ventricular tachycardia (VT) after myocardial infarction. He underwent resection of the left ventricular aneurysm and cryocoagulation of the arrhythmogenic foci. On the 2nd post-operative day, VT often recurred in spite of repeated cardioversion and drug therapy, and threatened his life, even under IABP. Therefore, a veno-arterial bypass route was made and extracorporeal lung and heart assist, ECLHA, was started with a heparin bonded Maxima lung on the following day. Even under ECLHA, VT continued to recur. Cryocoagulation of the VT foci was tried again, without immediate success. A record high dose of beta-blockers, given under the circulatory support by ECLHA, stopped VT on the following day. The patient was weaned from the ECLHA circuit 12 days after the first operation, then from IABP on the 14th day. During the 10 day course of surgeries and ECLHA, the patient had almost 100 defibrillations. But for ECLHA, we may say that the patient couldn't have survived two open heart surgeries, administration of a great amount of beta-blockers, and repeated cardiac arrest without neurological sequelae.

Gas-exchange function of a preprimed pediatric oxygenator stored for one year for emergency cardiopulmonary bypass

To save priming time and perform more rapid initiation of emergency cardiopulmonary bypass for acute cardiopulmonary failure, an extracorporeal circuit with a hollow-fiber oxygenator (EL-2000 for pediatric use; Kurary Co. Ltd., Osaka, Japan) was preprimed, and the gas-exchange function was evaluated after 1 year of storage. EL-2000 has a dense polyolefin membrane with a surface area of 0.3 m2. When the bypass flow rates were 250, 500, 1,000, and 1,500 ml/min with 100% oxygen at the same flow rate as the bypass blood flow (namely, V/Q = 1) to the oxygenator, oxygen transport rates of the stored oxygenator were 19.6 +/- 0.3, 38.3 +/- 0.41, 64.4 +/- 0.9, and 76.4 +/- 2.7 ml/min (n = 5, mean +/- SD), respectively. PCO2 differences between pre- and postoxygenator blood (delta PCO2) were 18.6 +/- 1.4, 12.0 +/- 1.6, and 4.4 +/- 1.2 mm Hg at V/Q = 1 and the same bypass blood flow rates, respectively, excluding 1,500 ml/min, the data for which were excluded because of preparatory failure. PCO2 removal indices (defined as the ratio of delta PCO2 to PCO2 in preoxygenator blood) were 0.45 +/- 0.03, 0.29 +/- 0.12, and 0.10 +/- 0.03, respectively. Though the evaluation was done using only a single oxygenator, we feel strongly that the gas-exchange function of the preprimed dense-membrane hollow fiber oxygenator will be preserved even after 1 year of storage.

A murine model of allergic bronchopulmonary aspergillosis with elevated eosinophils and IgE

A model of allergic bronchopulmonary aspergillosis was developed by exposing BALB/c mice to Aspergillus fumigatus (AF) Ag. Animals immunized intranasally (i.n.) with soluble AF Ag produced low levels of serum IgE compared to animals given alum precipitated AF Ag i.p. The latter treatment also produced higher levels of serum IgG1 and AF-specific IgG1 than soluble AF given i.p. or i.n.. Blood and lung eosinophilia was detected in mice repeatedly exposed to AF by i.n. but not in the groups injected i.p. Particulate AF Ag-induced striking blood and lung eosinophilia and elevated levels of serum IgE in mice preexposed to AF Ag. The results indicate that route of inoculation and physical nature of Ag determine the immune response and can be manipulated to obtain enhanced IgE, eosinophils, or both in the animal model.

A murine model of allergic bronchopulmonary aspergillosis with elevated eosinophils and IgE

A model of allergic bronchopulmonary aspergillosis was developed by exposing BALB/c mice to Aspergillus fumigatus (AF) Ag. Animals immunized intranasally (i.n.) with soluble AF Ag produced low levels of serum IgE compared to animals given alum precipitated AF Ag i.p. The latter treatment also produced higher levels of serum IgG1 and AF-specific IgG1 than soluble AF given i.p. or i.n.. Blood and lung eosinophilia was detected in mice repeatedly exposed to AF by i.n. but not in the groups injected i.p. Particulate AF Ag-induced striking blood and lung eosinophilia and elevated levels of serum IgE in mice preexposed to AF Ag. The results indicate that route of inoculation and physical nature of Ag determine the immune response and can be manipulated to obtain enhanced IgE, eosinophils, or both in the animal model.

Incidence estimation of genitourinary cancer in Korea

A nation-wide study was performed to estimate the incidence of bladder, kidney, renal pelvis and ureter, prostate, testicular and other genitourinary cancer among Koreans in Korea using medical records of the inpatients of the beneficiaries of the Korea Medical Insurance Corporation (KMIC) from Jan. 1, 1989 to Dec. 31, 1989. The crude incidence rate of bladder cancer (ICD-9 188) is estimated to be 4.43 and 0.98 per 100,000 in males and females, respectively. Around 1,093 new cases of bladder cancer (895 male and 198 female) are estimated to occur in a year. The adjusted rate for the world population is 7.76 in males and 1.19 in females which is similar to that of Japanese in Osaka and Chinese in Shanghai, but lower than in American whites and blacks. The crude incidence of kidney, renal pelvis and ureteral cancer (ICD-9 189) is estimated to be 1.61 and 0.87 in males and females, respectively. Around 507 new cases of kidney, renal pelvis and ureteral cancer (332 male and 175 female) are estimated to occur in a year. The adjusted rate for the world population is 2.69 in males and 1.04 in females. In the prostate (ICD-9 185), the crude incidence rate of cancer is estimated to be 1.36. Around 274 new cases of prostate cancer are occurring in a year. The adjusted rate for the world population is 2.98 which is similar to the Chinese rate. The incidence of genitourinary cancer continuously increases with age.

Structural analysis on the single-stranded genomic DNAs of the virus newly isolated from silkworm: the DNA molecules share a common terminal sequence

Recently, a parvo-like virus was newly isolated from silkworm larvae and the two viral DNAs (VD1 and VD2) with different electro-mobilities were identified. We cloned the viral DNAs in a plasmid pUC119 and demonstrated that these two DNAs were not a bimorphic molecules though they shared a common terminal sequence of 53 nucleotides. In addition, the sequence at the 5' terminus of each strand of the viral DNA was located in inverted form at its 3' terminus. On the other hand, the nucleotide sequences of VD1 and VD2 were different from that of the Bombyx densovirus (Ina isolate) DNA.

MR imaging characteristics of noncancerous lesions of the prostate

Radical prostatectomy specimens from 53 men with clinical stage A or B prostate cancer were retrospectively reviewed and compared with correlative axial T2-weighted magnetic resonance (MR) images obtained just before surgery. Non-cancerous lesions were evaluated for signal intensity and location. Focal high-signal-intensity areas (n = 72) were present in 81% of patients. The 26% of lesions seen in the central gland all correlated with cystic atrophy. Of the 53 lesions seen in the peripheral prostate, 47 (89%) were cystic atrophy without associated cancer, four (7.5%) cystic atrophy with cancer, and two (3.8%) focal inflammation. Focal low-signal-intensity areas (n = 42) were present in 60% of patients. Of the 31% of lesions in the central prostate, one-fifth correlated with benign prostatic hyperplasia (BPH) and four-fifths with fibrous tissue. Of the 69% of peripheral lesions, 83% corresponded to fibrous tissue, 10% to BPH, and 7% to normal tissue. Mixed lesions (n = 42) were present in 64% of patients; 86% of these were located centrally and 14% peripherally. All mixed central lesions were BPH; the peripheral lesions were areas of combined cystic atrophy and fibrosis. BPH of low or mixed signal intensity can extend into the peripheral prostate and mimic cancer. High-intensity cystic atrophy associated with cancer can mimic normal tissue.

Thrombin and parathyroid hormone mobilize intracellular calcium in rat osteosarcoma cells by distinct pathways

The mechanisms by which PTH and thrombin mobilize intracellular Ca2+ (Cai2+) were examined in UMR 106-H5 rat osteosarcoma cells. Bovine PTH-(1-34) (24 pM to 240 nM) produced a dose-dependent increase in Cai2+ (EC50, 3 nM), which returned to baseline within 75 sec. Human alpha-thrombin produced an increase in Cai2+ (ECmax, 10 U/ml) which was similar to that of PTH with respect to both magnitude and time course. Chelation of extracellular calcium with 5.0 mM EGTA did not alter the Cai2+ response to either PTH or thrombin. When added together at maximally effective concentrations, PTH and thrombin produced additive effects on Cai2+ in the presence and absence of EGTA. The additive effects of PTH and thrombin on Cai2+ were confirmed at the single cell level, using laser-based image analysis. Bradykinin (1 microM) produced a significant increase in Cai2+ in UMR 106-H5 cells which was of lesser magnitude than the peak 2- to 3-fold increase elicited by PTH or thrombin. Preexposure of cells to 10 U/ml thrombin for 2 min abolished the Cai2+ response to bradykinin, whereas preexposure to 240 nM PTH had no effect on the Cai2+ response to bradykinin. Thrombin elicited a rapid increase in the accumulation of 3H-labeled inositol phosphates (IP2 and IP3) in UMR 106-H5 cells, with increases in [3H]1,4,5-IP3 detectable as early as 15 sec after the addition of thrombin. Bradykinin increased [3H]IP production to a lesser extent than thrombin, whereas PTH neither increased [3H]IP accumulation nor potentiated the [3H]IP response to thrombin. The results suggest that thrombin and bradykinin mobilize Cai2+ from a shared IP3-responsive calcium pool, whereas PTH may use signals in addition to 1,4,5-IP3 to mobilize calcium from a distinct cellular calcium pool. Alternatively, specific calcium compartmentalization exists, and there is differential coupling of these agonists to the 1,4,5-IP3/Cai2+ pathway.

Soft-tissue sarcoma: MR imaging vs sonography for detection of local recurrence after surgery

To determine the value of MR and sonography in detecting local recurrences of soft-tissue sarcomas after surgery, 26 MR and sonographic studies performed in 21 patients were reviewed retrospectively. Recurrences were confirmed histologically in 12 (46%) of 26 studies. The MR images and sonograms were obtained within 1 month of each other. The findings were classified as recurrence, no recurrence, or indeterminate. Sonography was instrumental in guiding fine-needle aspiration biopsy of impalpable lesions. In two cases, the findings on sonography were indeterminate. In both of these cases, the sonograms had been obtained soon after surgery (at 2 and 4 months). The sensitivity and specificity in the detection of local recurrences were 83% and 93%, respectively, for MR and 100% and 79%, respectively, for sonography. These differences were not statistically significant. We conclude that MR and sonography appear to be equally useful in the detection of local recurrences of soft-tissue sarcomas, sonography can be used for routine follow-up and in guiding needle biopsies, sonography may be more difficult to interpret than MR during the early postoperative period, and MR should be used if sonography is inconclusive.

Terminal structure of a Densovirus implies a hairpin transfer replication which is similar to the model for AAV

We cloned the complete sequence of Bombyx DNV (Ina isolate; Bm DNV-1) genome in a bacterial plasmid pUC 119 and determined the nucleotide sequences of both termini, resulting in elucidation of the nucleotide sequence of the complete genomic DNA of DNV. The complete sequence of the DNV DNA (5048 nucleotides) has inverted repeats of 225 nucleotides and the terminal 153 nucleotides are palindromic. The palindromes can fold back on themselves to form a hairpin structure but, unlike AAV, the small internal palindrome which forms a T-shaped conformation was not observed. End-label analysis demonstrated that the palindromic sequences at both termini can exist in either of two orientations (flip or flop) in virion DNA with different frequencies. These data suggest that the hairpin transfer model for AAV replication must be modified to explain the DNV replication. Additionally, a comparison study on the terminal structures of insect, human, and rodent parvoviruses allowed a prediction on the ancestral terminal structure of parvovirus genome.

Electrical stimulation of the medial amygdala facilitates gastric acid secretion in conscious rats

One hundred and twenty-seven conscious rats prepared with chronic gastric fistula were studied to investigate the effect of stimulation of the medial amygdala on gastric acid secretion. Gastric acid output was significantly increased by electrical stimulation of the medial amygdala in normal rats and the increase in acid secretion was completely abolished by vagotomy. Vagotomized rats, with or without amygdaloid stimulation, showed comparable levels of gastric acid output which were significantly lower than in controls. These results indicate that the amygdala effect on gastric acid secretion is carried via the vagus nerve. Subcutaneous injections of high doses of histamine increased gastric acid secretion which was further increased by amygdaloid stimulation. Plasma levels of gastrin were not significantly changed by stimulation of the medial amygdala with or without vagotomy. From the above results, we concluded that in conscious rats the medial amygdala plays a significant role in stimulating gastric acid secretion, the vagus nerve is involved in this process, but it is not mediated by release of either histamine or gastrin.

The effect of experimental varicocele on the testis of adolescent rats

Experimental varicocele was created by partial ligation of the left renal vein in rats 4, 7 and 12 weeks old to compare the effects of varicocele on the testis at different times of onset: prepuberty, adolescence and adulthood. We examined the testes at 4 and 8 weeks after creation of the varicocele. The experimental groups of rats 4 and 12 weeks old showed slight testicular changes compared to control groups at 4 and 8 weeks postoperatively. In the 7-week group left testicular weight was significantly decreased (1.03 +/- 0.31 gm.) compared to that of the control group (1.51 +/- 0.12 gm.) at 4 weeks. The seminiferous tubular diameter in the left testis also was significantly reduced (219 +/- 37 microns) compared to that of the control group (270 +/- 14 microns). Histological changes, such as degeneration of germinal epithelium, tubular atrophy, Sertoli cell hyperplasia and interstitial edema, were observed more frequently in the 7-week group. At 8 weeks these changes were less significant. Our results suggest that varicocele during adolescence has the most damaging effects on the testis in rats.

Quantitative testicular biopsy in congenital and acquired genital obstruction

To determine if congenital obstruction of the genital tract is associated with significant testicular histopathological conditions compared to acquired forms of obstruction we performed testicular biopsy in 8 vasectomized men and 5 men with vasal agenesis. Quantitative analysis of the seminiferous tubular and epithelial parameters demonstrated a statistically significant increase in tubular wall thickness in the vasectomized group. There was no significant difference among the groups with reference to the mean number of late spermatids per seminiferous tubules, mean number of Sertoli cells per seminiferous tubules, mean number of seminiferous tubules per field (100 times) or mean seminiferous tubular diameter. We conclude that despite a lifelong duration of obstruction, men with vasal agenesis demonstrate a more favorable testicular histological status compared to men after vasectomy. This finding may have therapeutic implications when considering assisted pregnancy techniques as a method of treatment of male genital tract atresia.

Immunopathological response of C57BL/6 and C3H/HeN mice to Aspergillus fumigatus antigens

C3H/HeN and C57BL/6 mice were exposed to culture filtrate (CF) and mycelial extracts (ME) of Aspergillus fumigatus (Af) intranasally. Animals received 6, 8 or 10 biweekly doses and were sacrificed 2 weeks after the last dose was administered. Specific antibodies against Af were detected in their sera by biotin-avidin-linked immunosorbent assay (BALISA). Antibodies against Af belonging to all isotypes showed an increase in both strains of mice. A progressive increase in IgG and IgA antibody isotypes against both CF and ME antigens was detected in C3H/HeN mice during the entire experimental period, whereas most antibody levels peaked after the 8th dose and remained steady or decreased slightly in the C57BL/6 strain. Lung lavage studies showed a relative decrease in the number of macrophages and an increase in the number of lymphocytes after the 6th and 8th instillation of Af antigens in both strains of mice. Histology of the lung demonstrated a progressive inflammatory reaction in C57BL/6 mice during the experimental period. On the other hand, the C3H/HeN mice showed a negligible inflammatory pulmonary reaction. The antibody responses and inflammatory changes detected in the lungs of mice exposed to Af antigens are comparable to allergic bronchopulmonary aspergillosis (ABPA) in humans and hence this model will be of value in understanding the disease mechanism in ABPA and related diseases.

Effect of dopamine on electrical activity of isolated stomach muscle in cats

The effect of dopamine on electrical activity (gastric slow wave) of the stomach was studied in isolated stomach muscle strips of 145 cats. The gastric slow wave was recorded by four monopolar electrodes (Ag-AgCl) in Krebs-Ringer solution (pH 7.4, temperature 36 +/- 0.5 degrees C) bubbled with 5% CO2 in O2. Dopamine induced concentration-dependent alterations in frequency and propagation of slow waves. Development of irregular propagation was significantly suppressed by domperidone pretreatment. The variation of dopamine-induced slow-wave frequency was significantly inhibited by domperidone and phentolamine but not by propranolol, hexamethonium, and tetrodotoxin. The study indicates that a dopamine receptor exists in the stomach and plays a role in the genesis of gastric electrical abnormality.

A survey of externally recognizable genitourinary anomalies in Korean newborns. Korean Urological Association

To estimate the incidence of externally recognizable genitourinary anomalies and associated anomalies in the newborns in Korea, retrospective and prospective studies have been performed. Thirty eight of 48 urology training hospitals participated in this nationwide survey. In this study we have included minor defects or variations in the anomaly to evaluate the incidence of the recognizable genitourinary conditions in the newborns. The incidence of genitourinary anomaly in 1,000 newborn delivery in a year was 11.0 in the prospective study and this figure is about three times higher than the retrospective study and is considered to be close to the true incidence. The incidence of genitourinary anomaly in 1,000 male newborn was 20.4. Hydrocele, cryptorchidism and hypospadias were most commonly observed. The incidence of hydrocele in 1,000 male newborn was 9.89 and the incidence of cryptorchidism was 7.26 and the incidence of hypospadias was 2.13. The incidence of associated anomaly in 100 genitourinary anomaly was 7.9. Congenital heart diseases and anorectal anomalies were commonly associated anomalies. In the newborns with genitourinary anomalies, premature infants account larger portion than is usually reported in total delivery.

The influence of natural killer cells in neuroblastoma

Human neuroblastoma (NRB) cell lines are markedly sensitive to natural killer (NK) cell lysis in vitro, but patients with NRBs have low or absent NK activity. This study evaluated the NK sensitivity of murine NRBs (C1300 and TBJ) in the regulation of NRB growth and determined the effects of recombinant (r) interferon gamma and recombinant interleukin 2 (rIL-2). Both basal (8% +/- 3% specific cytotoxicity) and induced (20% +/- 3%) NK lyses of C1300-NRB were observed. In vivo depletion of NK cells with anti-asialo GM-1 significantly enhanced growth of C1300-NRB and decreased survival. Treatment with r-interferon gamma or rIL-2 on days 1 through 3 after C1300-NRB inoculation significantly prolonged the mean tumor latency period, decreased the tumor growth rate, and enhanced in vitro NK killing of C1300-NRB and YAC-1. The effects of r-interferon gamma and IL-2 were abrogated by pretreatment with anti-asialo GM-1. These results demonstrated that NK cells form one important component of regulation of a murine NRB, but immunomodulation with potent lymphokines requires cooperation of more than one cell type.