Effect of Adjuvant Chemotherapy in Highly Malignant Non-Metastatic Prostate Cancer: An Interim Analysis of Non-Randomized Comparative Trials

PURPOSE/OBJECTIVE(S)

Gleason grade group 5 (GG5) prostate cancers is aggressive with high metastatic rates and is not sensitive to androgen deprivation therapy (ADT). Even the presence of a limited (tertiary) Gleason pattern 5 component may have high aggressive biological behavior. This study aims to prospectively evaluate whether a non-androgen receptor pathway therapy - adjuvant chemotherapy could improve clinical outcomes among non-metastatic prostate cancer with the above highly malignant characters.

MATERIALS/METHODS

This prospective non-randomized clinical trial included non-metastatic prostate cancer patients with pathologically proven Gleason score of 9-10 or tertiary Gleason pattern 5. Each subject was allowed to decide whether to receive four to six cycles chemotherapy of docetaxel after receiving a standard treatment (i.e., radical surgery ± radiotherapy or radical radiotherapy combined with long-term ADT). The primary endpoint was event-free survival (EFS). Event was defined as any of biochemical failure or imaging failure, or change of systemic therapy due to PSA arises, or death. The secondary end points were distant metastasis-free survival (MFS), overall survival (OS), and treatment-related adverse events.

RESULTS

A total of 188 consecutive patients were enrolled from November 2019 to November 2022. Median prostate-specific antigen was 26.6 ng/ml. 52% had T3b to T4 disease, 27% had N1 disease. 140 patients received standard therapy only, and 48 patients received adjuvant chemotherapy after radical therapy. The median follow-up time was 18.4 (3.0-36.7) months. The estimated 36-month EFS of the chemotherapy group and the control group were 94.7% vs. 72.8% (p = 0.044). There were 1 event who added novel endocrine therapy in the chemotherapy group, and 21 events in the control group, including 6 cases of biochemical recurrence and 9 cases of lymph node and distant metastasis, 4 cases that changed systemic therapy and 2 cases died. The MFS of the two groups at 36 months were 100% and 90.7%, respectively (P = 0.143). After the 1:1 propensity score match, the EFS and MFS of the two groups were 94.7% and 80.8% (P = 0.069), and 100% and 93.1% (P = 0.132), respectively. The urinary toxicity of grade 2 and 3 in the chemotherapy group and the control group were 4.2% and 7.1% (P = 0.134) while the grade 2 rectal toxicity were 5.0% and 10.4% (P = 0.317), respectively. No grade 4 toxicity occurred. Considering the chemotherapy-related side effects, grade 3 or above toxicity were leukopenia (41.7%), alopecia (27.1%), thrombocytopenia (2.1%) and edema (2.1%).

CONCLUSION

Results of this interim analysis shows that the addition of adjuvant chemotherapy after standard radical therapy tends to improve the overall recurrence and metastasis free survival of patients with highly malignant prostate cancer, and the adverse effects are tolerable, which should be confirmed by long-term follow-up results.

[Epidemiologic characteristics and influencing factors of influenza outbreaks in Guangdong Province, 2015-2022]

Objective: To grasp the epidemiological characteristics of influenza outbreaks in Guangdong Province by analyzing the outbreaks of influenza-like cases reported in Guangdong Province from January 2015 to the end of August 2022. Methods: In response to the outbreak of epidemics in Guangdong Province from 2015 to 2022, information on on-site epidemic control was collected, and epidemiological analysis was conducted to describe the characteristics of the epidemics. The factors that influence the intensity and duration of the outbreak were determined through a logistic regression model. Results: A total of 1 901 influenza outbreaks were reported in Guangdong Province, with an overall incidence of 2.05%. Most outbreak reports occurred from November to January of the following year (50.24%, 955/1 901) and from April to June (29.88%, 568/1 901). A total of 59.23% (1 126/1 901) of the outbreaks were reported in the Pearl River Delta region, and primary and secondary schools were the main places where outbreaks occurred (88.01%, 1 673/1 901). Outbreaks with 10-29 cases were the most common (66.18%, 1 258/1 901), and most outbreaks lasted less than seven days (50.93%,906/1 779). The size of the outbreak was related to the nursery school (aOR=0.38, 95%CI:0.15-0.93), the Pearl River Delta region (aOR=0.60, 95%CI:0.44-0.83), the time interval between the onset of the first case and the time of report (>7 days compared with ≤3 days: aOR=3.01, 95%CI:1.84-4.90), the influenza A(H1N1) (aOR=2.02, 95%CI:1.15-3.55) and the influenza B (Yamagata) (aOR=2.94, 95%CI: 1.50-5.76). The duration of outbreaks was related to school closures (aOR=0.65, 95%CI: 0.47-0.89), the Pearl River Delta region (aOR=0.65, 95%CI: 0.50-0.83) and the time interval between the onset of the first case and the time of report (>7 days compared with ≤3 days: aOR=13.33, 95%CI: 8.80-20.19; 4-7 days compared with ≤3 days: aOR=2.56, 95%CI: 1.81-3.61). Conclusions: An influenza outbreak in Guangdong Province exhibits two peaks, one in the winter and spring seasons and the other in the summer. Primary and secondary schools are high-risk areas, and early reporting of outbreaks is critical for controlling influenza outbreaks in schools. Furthermore, comprehensive measures should be taken to prevent the spread of the epidemic.

[Thoracic SMARCA4-deficient undifferentiated tumor-pathological diagnosis and combined immune checkpoint inhibitor treatment]

We explored clinicopathological features and treatment strategies for thoracic SMARCA4-deficient undifferentiated tumor (SMARCA4-UT). Thoracic SMARCA4-UT is a new entity recently acknowledged in the 2021 edition of World Health Organization Classification of Thoracic Tumors, and doctors are relatively unfamiliar with its diagnosis, treatment, and prognosis. Taking a case of SMARCA4-UT treated in Peking University First Hospital as an example, this multi-disciplinary discussion covered several hot issues on diagnosing and treating thoracic SMARCA4-UT, including histological features, immu- nohistochemical and molecular phenotype, immune checkpoint inhibitor (ICI) therapy, and pathological assessment of neoadjuvant therapy response. The patient was an older man with a long history of smoking and was admitted due to a rapidly progressing solid tumor in the lower lobe of the right lung. Histologically, tumor cells were epithelioid, undifferentiated, diffusely positive for CD34, and partially positive for SALL4.The expression of BRG1 protein encoded by SMARCA4 gene was lost in all of tumor cells, and next-generation sequencing(NGS)confirmed SMARCA4 gene mutation (c.2196T>G, p.Y732Ter). The pathological diagnosis reached as thoracic SMARCA4-UT, and the preoperative TNM stage was T1N2M0 (ⅢA). Tumor proportion score (TPS) detected by immunohistochemistry of programmed cell death 1-ligand 1 (PD-L1, clone SP263) was 2%. Tumor mutation burden (TMB) detected by NGS of 1 021 genes was 16. 3/Mb. Microsatellite detection showed the tumor was microsatellite stable (MSS). Neo-adjuvant therapy was implemented with the combined regimen of chemotherapy and ICI. Right lower lobectomy was performed through thoracoscopy after the two weeks' neoadjuvant. The pathologic assessment of lung tumor specimens after neoadjuvant therapy revealed a complete pathological response (CPR). The post-neoadjuvant tumor TNM stage was ypT0N0M0. Then, five cycles of adjuvant therapy were completed. Until October 2022, neither tumor recurrence nor metastasis was detected, and minimal residual disease (MRD) detection was negative. At present, it is believed that if BRG1 immunohistochemical staining is negative, regardless of whether SMARCA4 gene mutation is detected, it should be classified as SMARCA4-deficient tumors. SMARCA4-deficient tumors include a variety of carcinomas and sarcomas. The essential criteria for diagnosing SMARCA4-UT includes loss of BRG1 expression, speci-fic histological morphology, and exclude other common thoracic malignant tumors with SMARCA4-deficiency, such as squamous cell carcinoma, adenocarcinoma and large cell carcinoma. SMARCA4-UT is a very aggressive malignant tumor with a poor prognosis. It has almost no targeted therapy mutations, and little response to chemotherapy, but ICI is currently the only effective drug. The successful diagnosis and treatment for this case of SMARCA4-UT should enlighten significance for various kinds of SMARCA4-deficient tumors.

[Nutritional status predicts clinical outcomes in patients with gastric cancer undergoing radical gastrectomy]

Objective: To evaluate the effect of nutritional status on clinical and pathological data for stage Ⅰ-Ⅳ gastric cancer patients from the cancer survival investigation information. Methods: A database of 302 consecutive gastric cancer patients underwent radical gastrectomy was enrolled in this study. The clinical and pathological information of them were corrected and the relationship between the nutritional index and the patients survival time were analyzed by a Cox regression model. Results: The clinical data analysis of 302 patients with gastric cancer who received total gastric resection indicated that the nutritional status was related to the stage of tumor patients, suggesting that the later the stage was, the more necessary the nutritional therapy intervention was. Univariate analysis showed that Ⅲ+Ⅳ of TNM staging (HR=4.417, 95%CI:2.483-6.351; P =0.029), patient age of 65 and above (HR=2.217, 95%CI:0.522-3.912; P =0.038), lymph node metastasis positive (HR=2.517, 95%CI:0.516-4.518; P=0.036), poor tumor differentiation (HR=3.626, 95%CI:0.721-6.531; P =0.021) and low PNI (HR=2.612, 95%CI: 0.712-4.512; P =0.029) is an important risk factor for poor prognosis. In the multivariate analysis, Ⅲ+Ⅳ of TNM staging (HR=3.821, 95%CI:1.923-5.719; P =0.014), patient age of 65 and above (HR=1.168, 95%CI:0.321-2.015; P =0.036) and low PNI (HR=2.435, 95%CI:1.024-3.846; P =0.039) was independently correlated with poor survival time; When age was used as a stratification factor, the correlation between CONUT recurrence and survival in patients with gastric cancer ≥65 years old after total gastric resection was analyzed and compared. For disease-free survival, the CONUT high group (>3) was 25.2 months, while the CONUT low group (≤3) was 30.9 months, (χ²=3.763,P=0.029), showing a significant difference. For the overall survival, the CONUT high(>3) group was 30.3 months, compared with the CONUT low(≤3) group at 34.5 months, (χ²=4.924,P=0.042), and the difference was also statistically significant. Conclusions: High controlling nutritional status is an independent risk factor associated with poor gastric cancer survival and it is an independent risk factor in predicting overall survival (OS) in elderly (≥65) gastric cancer after radical gastrectomy.

A mixed community of skin microbiome representatives influences cutaneous processes more than individual members

BACKGROUND

Skin, the largest organ of the human body by weight, hosts a diversity of microorganisms that can influence health. The microbial residents of the skin are now appreciated for their roles in host immune interactions, wound healing, colonization resistance, and various skin disorders. Still, much remains to be discovered in terms of the host pathways influenced by skin microorganisms, as well as the higher-level skin properties impacted through these microbe-host interactions. Towards this direction, recent efforts using mouse models point to pronounced changes in the transcriptional profiles of the skin in response to the presence of a microbial community. However, there is a need to quantify the roles of microorganisms at both the individual and community-level in healthy human skin. In this study, we utilize human skin equivalents to study the effects of individual taxa and a microbial community in a precisely controlled context. Through transcriptomics analysis, we identify key genes and pathways influenced by skin microbes, and we also characterize higher-level impacts on skin processes and properties through histological analyses.

RESULTS

The presence of a microbiome on a 3D skin tissue model led to significantly altered patterns of gene expression, influencing genes involved in the regulation of apoptosis, proliferation, and the extracellular matrix (among others). Moreover, microbiome treatment influenced the thickness of the epidermal layer, reduced the number of actively proliferating cells, and increased filaggrin expression. Many of these findings were evident upon treatment with the mixed community, but either not detected or less pronounced in treatments by single microorganisms, underscoring the impact that a diverse skin microbiome has on the host.

CONCLUSIONS

This work contributes to the understanding of how microbiome constituents individually and collectively influence human skin processes and properties. The results show that, while it is important to understand the effect of individual microbes on the host, a full community of microbes has unique and pronounced effects on the skin. Thus, in its impacts on the host, the skin microbiome is more than the sum of its parts. Video abstract.

A high-throughput drop microfluidic system for virus culture and analysis

High mutation rates and short replication times lead to rapid evolution in RNA viruses. New tools for high-throughput culture and analysis of viral phenotypes will enable more effective studies of viral evolutionary processes. A water-in-oil drop microfluidic system to study virus-cell interactions at the single event level on a massively parallel scale is described here. Murine norovirus (MNV-1) particles were co-encapsulated with individual RAW 264.7 cells in 65 pL aqueous drops formed by flow focusing in 50 μm microchannels. At low multiplicity of infection (MOI), viral titers increased greatly, reaching a maximum 18 h post-encapsulation. This system was employed to evaluate MNV-1 escape from a neutralizing monoclonal antibody (clone A6.2). Further, the system was validated as a means for testing escape from antibody neutralization using a series of viral point mutants. Finally, the replicative capacity of single viral particles in drops under antibody stress was tested. Under standard conditions, many RNA virus stocks harbor minority populations of genotypic and phenotypic variants, resulting in quasispecies. These data show that when single cells are encapsulated with single viral particles under antibody stress without competition from other virions, the number of resulting infectious particles is nearly equivalent to the number of viral genomes present. These findings suggest that lower fitness virions can infect cells successfully and replicate, indicating that the microfluidics system may serve as an effective tool for isolating mutants that escape evolutionary stressors.

Clinical manifestations and radiological features may contribute to the early diagnosis of radiation-induced sarcoma after breast cancer

AIM

To describe the clinical manifestations and radiological features contributing to the early diagnosis of radiation-induced sarcoma (RIS) after radiotherapy for breast cancer.

MATERIALS AND METHODS

This retrospective analysis included four typical cases of RIS diagnosed at Affiliated Hospital of Academy of Military Medical Sciences between 1980 and 2013. Patient and imaging characteristics, treatment modalities, and outcomes were extracted from patients' medical records. Two pathologists reviewed all histological slides.

RESULTS

All four cases were misdiagnosed and treated for several months as cases of breast cancer relapse. CT using the bone-window setting and three-dimensional reconstructions clearly displayed bone tumours of RIS in three cases. Skin alterations were observed in all cases. At the time of RIS diagnosis, three patients were free of breast cancer. In one patient with bilateral breast cancer and lung metastasis, chemotherapy resulted in complete remission of the metastasis, but RIS progression. No RIS in this series responded to chemotherapy or endocrine therapy.

CONCLUSIONS

Abnormalities appearing in the radiation field long after RT should alert clinicians to the potential development of RIS. Careful physical examination and follow-up imaging studies are necessary. The presence of skin alterations, bone tumours at CT or radiography, and poor response to anti-cancer drugs may contribute to the early detection of RIS. Biopsy should be performed immediately when RIS is suspected.

The prevalence and distribution of bone defects in patients with moderate to advanced periodontitis

BACKGROUND

Alveolar bone defect is one of the common features of periodontitis and may vary in its form, extent, and distribution among teeth and individuals. The purpose of this study was to analyze the prevalence and distribution of different forms of bone defects in Taiwanese patients with moderate to advanced periodontitis.

METHODS

One hundred and thirty-seven Taiwanese patients with moderate to advanced periodontitis comprising a total sample of 3542 teeth were studied. During periodontal surgery, osseous defects were explored and classified as interproximal crater, 1-wall, 2-wall, 3-wall, hemiseptal and circumferential defects. Among them, some were also recorded as complicated defects.

RESULTS

Among 3542 existing teeth, 1376 were examined surgically and 483 teeth had bone defects. There was an increase in bone defects from anterior to posterior. The frequencies of defects in anterior and posterior segments were significantly different. More defects were found on the right side than on the left side. Yet there was no difference between the maxillary and mandibular arch. Interproximal surfaces of the first and second molars had the highest prevalence of bone defects. Crater was the most common defect type (26.50%), followed by circumferential (23.40%) and 3-wall defect (20.08%). More than 40% also presented with complicated defects.

CONCLUSIONS

There was an increase in bone defects from anterior to posterior. Interproximal aspects were more frequently involved than buccal or lingual aspects. Crater, circumferential and 3-wall defects were more common than other defect types. The treatment of complicated defects, which comprise over 40% of all defects, presents a challenging task for periodontists.

Comparison of ball-and-racquet impact force between two tennis backhand stroke techniqes

STUDY DESIGN

A mixed design for kinetic comparison of 2 types of one-handed backhand strokes and 2 skill levels in tennis.

OBJECTIVES

To develop and evaluate a model to estimate the impact force on the racquet during tennis stroke, and to compare the peak impact force between one-handed backhand stroke with a long backswing and one-handed backhand stroke with a short backswing and between the beginning and advanced players.

BACKGROUND

A one-handed backhand stroke is commonly used in tennis and may be associated with many upper extremity over-use injuries. An understanding of kinetics of the backhand stroke is essential for understanding injury mechanisms and prevention.

METHODS AND MEASURES

Five male advanced tennis players and 4 male and 1 female beginning tennis players participated. Mean age was 32.2 +/- 7.0 years. Each subject was instructed to use the 2 types of one-handed backhand strokes to hit balls from a tennis ball machine. Three-dimensional coordinates of critical body and racquet landmarks were obtained. A mathematical model was developed to estimate the contact duration and the peak impact force during a stroke.

RESULTS

The estimated peak impact forces were reproducible and comparable to those reported in the literature from direct measurements. A one-handed backhand stroke with a short backswing had a significantly shorter contact duration (0.008 +/- 0.003 seconds) and a greater peak resultant impact force (330.0 +/- 140.7) than that with a long backswing (0.016 +/- 0.004 seconds and 180.8 +/- 49.1 N). Skill level did not significantly affect the peak resultant impact force.

CONCLUSION

A long backswing in a one-handed backhand stroke may reduce the load on the upper extremity and may assist in reducing the risks of tennis-related upper extremity over-use injuries.

Classifiers and social control in wheelchair rugby

The purpose of this study was to examine the features of wheelchair rugby classifiers in order to maintain social control in wheelchair rugby. The examination centered on the theme-resources used by classifiers to maintain the authority of International Wheelchair Rugby Federation (IWRF). Data were collected using participant observation methodology at national and international wheelchair rugby championships and a survey of the 14 IWRF authorized classifiers. The results of this study identified five essential features of IWRF classifiers. In particular, they need to have a background in medicine or physical therapy. In addition, IWRF classifiers use their medical and sporting knowledge and experience to control the wheelchair rugby classification process and to maintain fairness of competition. The results of this study may help to train Taiwanese professionals with medical or sporting backgrounds to become international classifiers and also to develop appropriate training programs for national classifiers.

Factors influencing sport participation among athletes with spinal cord injury

OBJECTIVE

This exploratory study examined the relationships between pre- and post-injury sport participation among active individuals with spinal cord injury (SCI) in the United Kingdom. In particular, factors that influence individuals with SCI into sport were identified.

METHODS

A total of 143 British individuals with SCI currently participating in wheelchair basketball, wheelchair rugby, wheelchair tennis, and wheelchair athletics were recruited. A total of 112 subjects were active prelesion, and 31 subjects were inactive preinjury. A Disability Sport Participation questionnaire developed by the authors was used for data collection. The questionnaire was distributed through the British Wheelchair Sport Associations. Personal, impairment, health and fitness, socialization, and participation data of athletes with SCI were collected. Groups of active preinjury and inactive preinjury were compared.

RESULTS

For athletes who had been active pre-SCI, the in-hospital rehabilitation program and specialized sport club for people with disabilities were more important contexts for introducing the sport after injury to individuals. Friends and peers with disabilities were much more influential as initial and continuing socialization agents than rehabilitation therapists. The main reasons for athletes with SCI who participated in sports after injury were for fitness, fun, health, and competition, although many athletes noted that social aspects and rehabilitation also influenced their sport participation.

CONCLUSION

This study identified social contexts, social agents, difficulties, sources of information, and reasons for sport participation of athletes with SCI. The results may offer some directions for the improvement of rehabilitation programs for people with SCI and also help the development of appropriate strategies to encourage people with SCI to participate in sports and leisure activities.

The Size-Dependence of 1,5-Diphenyl-3-naphthyl-2-pyrazoline Nanocrystals

1,5-Diphenyl-3-naphthyl-2-pyrazoline nanocrystals with different sizes from 400 to 20 nm were prepared by the reprecipitation method. As the nanocrystal size decreased, the nanocrystal absorption peak was observed to shift to high-energy side due to size effect, and in the same period the peak shape changed from asymmetric to symmetric due to the gradual disappearance of the aggregate absorption. Copyright 1999 Academic Press.

Biopharmaceutics of transmucosal peptide and protein drug administration: role of transport mechanisms with a focus on the involvement of PepT1

Non-invasive delivery of peptide and protein drugs will soon become a reality. This is due partly to a better understanding of the endogenous transport mechanisms, including paracellular transport, endocytosis, and carrier-mediated transport of mucosal routes of peptide and protein drug administration. This paper focuses on work related to the elucidation of structure-function, intracellular trafficking, and regulation of the intestinal dipeptide transporter, PepT1.

Molecular role for the Rab binding platform of guanine nucleotide dissociation inhibitor in endoplasmic reticulum to Golgi transport

Guanine nucleotide dissociation inhibitor (GDI) regulates the recycling of Rab GTPases involved in vesicle targeting and fusion. We have analyzed the requirement for conserved amino acid residues in the binding of Rab1A and the function of GDI in transport of cargo between the endoplasmic reticulum (ER) and the Golgi apparatus. Using a new approach to monitor GDI-Rab interactions based on the change in fluorescence associated with the release of methylanthraniloyl guanosine di(tri)phosphate-GDP (mGDP) from Rab, we show that residues previously implicated in the binding of the synapse-specific Rab3A, including Gln-236, Arg-240, and Thr-248, are essential for the binding of Rab1A. Mutation of each of these residues has potent effects on the ability of GDI to remove Rab1A from membranes and inhibit ER to Golgi transport in vitro. Given the sequence divergence between Rab1A and 3A (35% identity), these residues are proposed to play a general role in GDI function in the cell. In contrast, several other residues found within or flanking the Rab-binding region were found to have differential effects in the recognition and recycling of Rab1A and 3A, and therefore direct selective interaction of GDI with individual Rab proteins. Intriguingly, mutation of one residue, Arg-70, led to a reduction of Rab1A binding, failed to extract Rab1A from membranes in vitro, yet bound membranes tightly and potently inhibited ER to Golgi transport. These results provide evidence that novel membrane-associated factor(s) mediate Rab-independent GDI interaction with membranes.

Molecular identification of a role for tyrosine 167 in the function of the human intestinal proton- coupled dipeptide transporter (hPepT1)

hPepT1 is a proton-coupled peptide transporter that mediates the absorption of di- and tripeptides. Here we show that tyrosine 167 (Y167) in transmembrane domain 5 (TMD5) of this 12-transmembrane spanning protein contributes to its transport function. We identified this particular amino acid by a computer model of the arrangement of the TMDs of hPepT1 and investigated its role by site-directed mutagenesis and dipeptide uptake studies. [3H]Gly-sar uptake in cells transiently transfected with Y167A-hPepT1 was abolished completely, even though the level of Y167A-hPepT1 expression by Western blot analysis and cell surface expression by immunofluorescence microscopy was similar to those of the wild type. Therefore, mutation affected transport function, but apparently not the steady-state protein level or trafficking of the transporter to the plasma membrane. Moreover, mutation of Y167 into phenylalanine, serine, or histidine all abolished gly-sar uptake in transfected HEK 293 cells. Taken together, these findings suggest that Y167 plays an essential role in hPepT1 function, perhaps due to the unique chemistry of its phenolic side chain.

Mutations in GDI1 are responsible for X-linked non-specific mental retardation

Rab GDP-dissociation inhibitors (GDI) are evolutionarily conserved proteins that play an essential role in the recycling of Rab GTPases required for vesicular transport through the secretory pathway. We have found mutations in the GDI1 gene (which encodes uGDI) in two families affected with X-linked non-specific mental retardation. One of the mutations caused a non-conservative substitution (L92P) which reduced binding and recycling of RAB3A, the second was a null mutation. Our results show that both functional and developmental alterations in the neuron may account for the severe impairment of learning abilities as a consequence of mutations in GDI1, emphasizing its critical role in development of human intellectual and learning abilities.

Dihydroorotate dehydrogenase inhibitors: quantitative structure-activity relationship analysis

PURPOSE

The main purpose of this study is to analyze the quantitative structure-activity relationship of two series of dihydroorotate dehydrogenase inhibitors (leflunomide and quinoline carboxylic acid analogues), and to determine the structural requirements for optimum activity of these analogues.

METHODS

A new CQSAR program was used in deriving regression equations and calculating the octanol/water partition coefficient and the molar refractivity values. The molecular modeling was performed using the HyperChem program.

RESULTS

Statistically significant correlations were obtained using a combination of 3-4 parameters. The structural requirements for optimum activity and critical regions for the inhibitory activity of dihydroorotate dehydrogenase were identified.

CONCLUSIONS

The quantitative structure-activity relationship analysis demonstrated that two series of dihydroorotate dehydrogenase inhibitors may bind to different binding sites on the enzyme. These results provide a better understanding of dihydroorotate dehydrogenase inhibitor-enzyme interactions, and may be useful for further modification and improvement of inhibitors of this important enzyme.

Cutaneous sinus tract caused by vertical root fracture

This report presents a rare case of odontogenic cutaneous sinus tract caused by a vertical root fracture. The root-fractured molar was probably caused by an accidental blow by a cow 3 years ago. Despite all treatments by physicians and surgeons for nearly 1 year, the sinus tract recurred repeatedly. After diagnosis and extraction of the fractured molar by the dentist, the sinus tract healed uneventfully in a month.

Mss4 does not function as an exchange factor for Rab in endoplasmic reticulum to Golgi transport

Mss4 and its yeast homologue, Dss4, have been proposed to function as guanine nucleotide exchange factors (GEFs) for a subset of Rab proteins in the secretory pathway. We have previously shown that Rab1A mutants defective in GTP-binding potently inhibit endoplasmic reticulum to Golgi transport, presumably by sequestering an unknown GEF regulating its function. We now demonstrate that these mutants stably associate with Mss4 both in vivo and in vitro and that Mss4 effectively neutralizes the inhibitory activity of the Rab1A mutants. An equivalent Rab3A mutant (Rab3A[N135I]), a Rab protein specifically involved in regulated secretion at the cell surface, associates with Mss4 as efficiently as the Rab1A[N124I] mutant. Although Rab3A[N135I] prevents the ability of Mss4 to neutralize the inhibitory effects of Rab1A mutants on transport, it has no effect on Rab1 function or endoplasmic reticulum to Golgi transport. Furthermore, quantitative immunodepletion of Mss4 fails to inhibit transport in vitro. We conclude that Mss4 and its yeast homologue, Dss4, are not GEFs mediating activation of Rab, but rather, they interact with the transient guanine nucleotide-free state, defining a new class of Ras-superfamily GTPase effectors that function as guanine nucleotide-free chaperones (GFCs).

Structural insights into the function of the Rab GDI superfamily

The 1.81 A crystal structure of Rab GDP-dissociation inhibitor (GDI), a protein that plays a critical role in the recycling of Rab GTPases involved in membrane vesicular transport, has been recently determined. Biochemical studies implicate a highly conserved region involved in Rab binding, which is common to both GDI and the evolutionarily-related choroideremia gene product (CHM/REP) required for Rab prenylation. Here, we summarize the mechanisms by which members of the GDI superfamily might function to coordinate events leading to membrane fusion, and we discuss the unexpected, yet striking structural homology of GDI to FAD-binding proteins.

Structure and mutational analysis of Rab GDP-dissociation inhibitor

The crystal structure of the bovine alpha-isoform of Rab GDP-dissociation inhibitor (GDI), which functions in vesicle-membrane transport to recycle and regulate Rab GTPases, has been determined to a resolution of 1.81 A. GDI is constructed of two main structural units, a large complex multisheet domain I and a smaller alpha-helical domain II. The structural organization of domain I is surprisingly closely related to FAD-containing monooxygenases and oxidases. Sequence-conserved regions common to GDI and the choroideraemia gene product, which delivers Rab to catalytic subunits of Rab geranylgeranyltransferase II, are clustered on one face of the molecule. The two most sequence-conserved regions, which form a compact structure at the apex of GDI, are shown by site-directed mutagenesis to play a critical role in the binding of Rab proteins.

Induction of superoxide dismutase isozymes by tumor necrosis factor-alpha and lipopolysaccharide in cultured normal and hyperplastic gingival fibroblasts

To determine whether lipopolysaccharide (LPS) and tumor necrosis factor-alpha (TNF-alpha) are involved in the induction of superoxide dismutase (SOD) in gingival tissue, we examined their effect on induction of SOD isozymes in cultured normal (NGF) and phenytoin-induced hyperplastic (PHF) gingival fibroblasts. Treatment of both NGFs and PHFs with 10 to 50 ng/mL TNF-alpha for 24 hours increased the level of manganese SOD (MnSOD) to as much as four times the level of untreated cultures. PHFs, but not NGFs, were shown to be responsive to TNF-alpha in eliciting a significant increase in copper-zinc SOD (Cu/ZnSOD), albeit in a lesser amount than MnSOD. Additionally, treatment of both types of cells with 5 to 50 mg/mL of LPS for 24 hours also elicited an increase in the levels of MnSOD. Again, an LPS-induced increase in Cu/ZnSOD levels could only be demonstrated in PHFs, but not in NGFs. These observations were further confirmed by comparing the achromatic bands associated with SOD isozymes exhibited in the electrophoretogram using a nondenaturing polyacrylamide electrophoresis technique. These results indicate that TNF-alpha and LPS were capable of inducing both MnSOD and Cu/ZnSOD simultaneously in PHF fibroblasts. PHFs may be inherently more capable than NGFs in combating oxidative stress.

A structure-function study of bovine pancreatic phospholipase A2 using polymerized mixed liposomes

A new combinatorial approach that includes the genetic variation of protein structure and the chemical modification of phospholipid structure in polymerized mixed liposomes was used to delineate the structure-function relationships in the interfacial catalysis of bovine pancreatic phospholipase A2 (PLA2). Based on previous structural and mutational studies, several bovine PLA2 mutants were generated in which a positive charge of putatively important lysyl side chains was reversed (K10E, K53E, K56E, and K116E) or neutralized (K56Q and K116Q). Kinetic parameters of bovine wild type and mutant PLA2s determined using polymerized mixed liposomes consisting of 1-hexadecanoyl-2-(1-pyrenedecanoyl)-sn-glycero-3-phosphoethanolamine (or -phosphoglycerol) and 1,2-bis[12-(lipoyloxy)dodecanoyl]-sn-glycero-3-phosphoglycerol showed that Lys-53 is involved specifically in the interaction with a substrate bound in the active site. Also, these results showed that Lys-10 and Lys-116 are involved in the interaction of bovine PLA2 with anionic interfaces but not in the interaction with the active site-bound substrate. In particular, Lys-116 makes more significant contribution than Lys-10 by approximately 1.0 kcal/mol to the binding to anionic interfaces. Most importantly, Lys-56 was shown to participate in the interaction with both the active site-bound substrate and anionic interfaces. These findings establish Lys-56 and Lys-116 as essential residues for the binding of bovine pancreatic PLA2 to anionic interfaces. Lastly, our structure-function analysis based on the use of polymerized mixed liposomes was further supported by equilibrium binding measurements of these proteins using 1,2-bis[12-(lipoyloxy)dodecanoyl]-sn-glycero-3-phosphoglycerol polymerized liposomes and by kinetic analyses using monomeric substrates, 1,2-dihexanoyl-sn-glycero-3-phosphoethanolamine and -phosphoglycerol.

Effects of specific fatty acid acylation of phospholipase A2 on its interfacial binding and catalysis

Monomeric phospholipase A2 (PLA2) from the venom of Agkistrodon piscivorus piscivorus (App-D49) was treated with 3-acyloxy-4-nitrobenzoic acids to acylate the epsilon-amino groups of two lysines (Lys-7 and Lys-10) in the amino terminal region. Resulting 7,10-diacylated-App-D49s, with acyl groups ranging from lauroyl to palmitoyl, spontaneously aggregated in solution. By contrast, 7,10-dioctanoyl-App-D49 existed as a monomer under the same condition. Kinetic and interfacial binding properties of diacylated enzymes indicated that they catalyzed the hydrolysis at the interface as a monomer. When compared to nonacylated App-D49, diacylated enzymes showed slightly increased activity or decreased activity toward monodispersed 1,2-dibutyryl-sn-glycero-3-phosphocholine, Triton X-100/1,2-dilauroyl-sn-glycero-3-phosphocholine mixed micelles, and small unilamellar vesicles (SUV) of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC). Toward densely-packed liquid-crystalline phospholipid bilayers, such as large unilamellar vesicles (LUV) of POPC, however, diacylated enzymes exhibited a large increase in activity, which reacted up to 250-fold for 7,10-dilauroyl-App-D49 ((kcat/Km)app = (1.0 +/- 0.02) x 10(6) M-1 s-1). Measurements of the penetration of individual diacylated enzymes into 2-oleoyl-3-palmitoyl-sn-glycero-1-phosphocholine (i.e., D-POPC) monolayers indicated that the acyl groups enhanced the interfacial binding of protein by interacting with hydrocarbon moieties of phospholipids and that these hydrophobic interactions remained effective even when the phospholipid packing density was high. Furthermore, fluorometric measurements of the binding of diacylated enzymes to polymerized vesicles of 1,2-bis[12-(lipoyloxy)dodecanoyl]-sn-glycero-3-phosphocholine showed that the hydrophobic interactions increased the enzymatic activity toward LUV by accelerating the migration of enzyme molecules to vesicle surfaces. The analysis of the kinetic course of POPC LUV hydrolysis showed that diacylated enzymes as a catalyst were superior to nonacylated App-D49 in that they were not only more catalytically efficient but also able to catalyze more turnovers without being trapped in product-containing vesicles. In summary, the acylation of App-D49 by 3-acyloxy-4-nitrobenzoic acids provides a simple and convenient way of converting the enzyme into a highly active form toward densely-packed liquid-crystalline phospholipid bilayers, which might have potential industrial and biomedical applications.

A continuous fluorometric assay for phospholipases using polymerized mixed liposomes

A versatile continuous fluorometric assay for phospholipases A2, C, and D has been developed utilizing polymerized mixed liposomes made of pyrene-containing phospholipids (5 mol%) uniformly inserted in the polymerized liposomes of 1,2-bis[12-(lipoyloxy)dodecanoyl]-sn-glycero-3-phosphoglycerol (BLPG) and its derivatives. 1-Hexadecanoyl-2-(1-pyrenedecanoyl)-sn-glycero-3-phosphocholine was used for phospholipase A2 and N-(1-pyrenesulfonyl)-egg phosphatidyl ethanolamine for phospholipases C and D. Fluorescence emission of pyrene moieties in polymerized mixed liposomes was strongly quenched by BLPG molecules and, thus, the hydrolysis of pyrene-containing phospholipids and the subsequent displacement of pyrene moieties from the liposomes resulted in a large increase in fluorescence intensity. All the phospholipases tested selectively and rapidly hydrolyzed the inserted pyrene-containing phospholipids, which were readily monitored by measuring an increase in fluorescence emission at 380 nm. Assay conditions for individual phospholipases were optimized by altering interfacial properties of polymerized liposomes, such as surface charge, and subsequently by changing the chemical structure of hydrolyzable phospholipids. Phospholipase activities were linearly proportional to enzyme concentrations in the range from 0.1 to 50 ng. Specific activity determined for phospholipases from a wide variety of sources ranged from 0.5 to 100 mumol/min/mg. Polymerized mixed liposomes are exceptionally stable against chemical and physical degradation and the assay requires only a small amount of pyrene-containing phospholipids. In addition, the polymerized matrix of BLPG (and its derivatives), due to its inertness to the phospholipase hydrolysis, allows the direct measurement of the equilibrium dissociation constant for a protein-liposome complex.

Use of polymerized mixed liposomes to study interactions of phospholipase A2 with membranes

Polymerized liposomes of thiol-based phospholipids, 1,2-bis[12-(lipoyloxy)dodecanoyl]-sn-glycero-3-phosphocholine (BLPC) and -phosphoglycerol (BLPG) were used to study interactions of several phospholipases A2 (PLA2) with membranes. Large liposomes (an average diameter of 100 +/- 10 nm) prepared from BLPC or BLPG were readily hydrolyzed by PLA2. Once polymerized, however, these liposomes were resistant to the PLA2 hydrolysis. When liposomes were prepared from a mixture of 1-hexadecanoyl-2-(1-pyrenyldecanoyl)-sn-glycero-3-phosphocholine (pyrene-PC) (5 mol%) and BLPC, fluorescence measurements of resulting polymerized mixed liposomes showed that the pyrene-PC molecules exist solely as monomers without forming a patch and were selectively hydrolyzed by PLA2. Progress of the hydrolysis can be readily monitored by measuring the change in fluorescence emission at 380 nm in the presence of bovine serum albumin. Rapid and selective hydrolysis of inserted phospholipids in polymerized mixed liposomes supports the notion that facile migration of a phospholipid substrate from membrane to the active site of enzyme is a critical step in the catalysis of PLA2. On the basis of these findings, various combinations of polymerized mixed liposomes were prepared and their hydrolysis by PLA2 measured. When compared to the substrate specificity of PLA2s determined using Triton X-100/phospholipid mixed micelles, results from polymerized mixed liposomes indicate that electrostatic interactions between the interfacial binding site of PLA2 and membrane surfaces play an important role in the determination of substrate specificity of PLA2 and in the regulation of PLA2 activities.(ABSTRACT TRUNCATED AT 250 WORDS)

A 300 bp 5′-upstream sequence of a differentiation-dependent rabbit K3 keratin gene can serve as a keratinocyte-specific promoter

Keratinocytes of the suprabasal compartment of many stratified epithelia synthesize as a major differentiation product a keratin pair, consisting of an acidic and a basic keratin, which accounts for 10–20% of the newly synthesized proteins. While genes of several differentiation-related keratins have been cloned and studied, relatively little is known about the molecular basis underlying their tissue-specific and differentiation-dependent expression. We have chosen to study, as a prototype of these genes, the gene of K3 keratin, which has the unique property of being expressed in the majority of corneal epithelial basal cells but suprabasally in peripheral cornea, the site of corneal epithelial stem cells. Using a monoclonal antibody, AE5, specific for K3 keratin, and a fragment of human K3 gene as probes, we have isolated several cDNA and genomic clones of rabbit K3 keratin. One genomic clone has been sequenced and characterized, and the identity of its coding sequence with that of cDNAs indicates that it corresponds to the single, functional rabbit K3 gene. Transfection assays showed that its 3.6 kb 5′-upstream sequence can drive a chloramphenicol acetyl transferase (CAT) reporter gene to express in cultured corneal and esophageal epithelial cells, but not in mesothelial and kidney epithelial cells or fibroblasts, all of rabbit origin. Serial deletion experiments narrowed this keratinocyte-specific promoter to within -300 bp upstream of the transcription initiation site. Its activity is not regulated by the coding or 3′-noncoding sequences that have been tested so far. This 300 bp 5′-upstream sequence of K3 keratin gene, which can function in vitro as a keratinocyte-specific promoter, contains two clusters of partially overlapping motifs, one with an NFkB consensus sequence and another with a GC box. The combinatorial effects of these multiple motifs and their cognate binding proteins may play an important role in regulating the expression of this tissue-restricted and differentiation-dependent keratin gene.

Full-length DQ beta cDNA sequences of HLA-DR2/DQw1 subtypes: genetic interactions between two DQ beta loci generate human class II HLA diversity

Two-dimensional gel electrophoresis of DQ molecules from three different Dw subtypes (Dw2, Dw12, and Dw21/FJO) of the HLA-DR2/DQw1 haplotype reveals that one alpha beta heterodimer of DQ molecule is expressed by each subtype and the DQ beta chain is electrophoretically variable among the three DR2/DQw1 subtypes. We have constructed cDNA libraries from the same homozygous typing cells used in the two-dimensional polyacrylamide gel electrophoresis analyses (HTC VYT for Dw2, HTC DHO for Dw12, and HTC FJO for Dw21/FJO) and isolated DQ beta cDNA clones with full-length coding sequences for each subtype. The deduced amino acid sequences show that the DQ beta chains of these three DR2/DQw1 subtypes are highly polymorphic and confirm their electrophoretic heterogeneity: for a mature protein of 229 amino acids, they differ with each other by 10-17 amino acids in the first domain and by 3-7 residues in the C-terminal sequence. Comparison among the available DQ beta sequences representing the four major DQ specificities (DQw1, DQw2, DQw3, and DQw4) in the DQ subregion as defined by serologic method suggests that (1) DR2,Dw2,DQw1 and DR3,DQw2 haplotypes probably interact with each other to generate the DQw3 and DQw4 beta alleles and (2) an evolutionary scheme may be proposed to relate the various beta alleles of the four major DQ specificities.

Molecular studies of a rare DR2/LD-5a/DQw3 HLA class II haplotype. Multiple genetic mechanisms in the generation of polymorphic HLA class II genes

A cDNA library was constructed from a homozygous B lymphoblastoid cell line (REM) obtained from an individual of a long isolated American Indian tribe, the Warao. The REM cell line expresses serologically defined determinants, DR2 and DQw3, and the T lymphocyte-defined (Dw/LD) specificity, LD-5a. T cells can recognize differences between FJO (a DR2/DQw1 cell line that expresses the Dw specificity MN2) and REM for both DR and DQ molecules. cNDA clones encoding the polymorphic DR beta 1-, DR beta 2-, DQ beta-, and DQ alpha-chains were sequenced and compared with other DR and DQ gene sequences. The DR beta 1-sequence of REM is identical to the DR beta 1-sequence of FJO; the DR beta 2-sequence is also identical to that of FJO except for one amino acid difference at position 67 in the polymorphic first domain (Leu in REM, Phe in FJO) due to a single point mutation. The DQ beta-sequence is identical to that of DR4/DQw3 haplotype; the DQ alpha is different from the DQ alpha of DR4/DQw3 haplotype and identical to the DQ alpha of both the DR3/DQw2 haplotype of a Raji cell line and the DR5/DQw3 haplotype in deduced amino acid sequence. Taken together, these findings suggest that: 1) a single amino acid difference (position 67) in the third hypervariable region of the first domain of the DR beta 2-chain in the DR2 haplotype is apparently sufficient for stimulating T cell responses; 2) the DQw3 serologic specificity may be defined mainly by the DQ beta-rather than DQ alpha-chain; and 3) multiple genetic events have probably occurred to generate the rarely found REM (DR2/LD-5a/DQw3) haplotype.

Molecular studies of a rare DR2/LD-5a/DQw3 HLA class II haplotype. Multiple genetic mechanisms in the generation of polymorphic HLA class II genes

A cDNA library was constructed from a homozygous B lymphoblastoid cell line (REM) obtained from an individual of a long isolated American Indian tribe, the Warao. The REM cell line expresses serologically defined determinants, DR2 and DQw3, and the T lymphocyte-defined (Dw/LD) specificity, LD-5a. T cells can recognize differences between FJO (a DR2/DQw1 cell line that expresses the Dw specificity MN2) and REM for both DR and DQ molecules. cNDA clones encoding the polymorphic DR beta 1-, DR beta 2-, DQ beta-, and DQ alpha-chains were sequenced and compared with other DR and DQ gene sequences. The DR beta 1-sequence of REM is identical to the DR beta 1-sequence of FJO; the DR beta 2-sequence is also identical to that of FJO except for one amino acid difference at position 67 in the polymorphic first domain (Leu in REM, Phe in FJO) due to a single point mutation. The DQ beta-sequence is identical to that of DR4/DQw3 haplotype; the DQ alpha is different from the DQ alpha of DR4/DQw3 haplotype and identical to the DQ alpha of both the DR3/DQw2 haplotype of a Raji cell line and the DR5/DQw3 haplotype in deduced amino acid sequence. Taken together, these findings suggest that: 1) a single amino acid difference (position 67) in the third hypervariable region of the first domain of the DR beta 2-chain in the DR2 haplotype is apparently sufficient for stimulating T cell responses; 2) the DQw3 serologic specificity may be defined mainly by the DQ beta-rather than DQ alpha-chain; and 3) multiple genetic events have probably occurred to generate the rarely found REM (DR2/LD-5a/DQw3) haplotype.

cDNA cloning and sequencing reveals that the electrophoretically constant DR beta 2 molecules, as well as the variable DR beta 1 molecules, from HLA-DR2 subtypes have different amino acid sequences including a hypervariable region for a functionally important epitope

Two-dimensional gel electrophoresis (2D-PAGE) of DR molecules from three different Dw subtypes (Dw2, Dw12, and FJO) of the HLA-DR2 haplotype reveals that at least two DR beta genes are expressed. Protein mixing experiments demonstrate that one of the two expressed DR beta molecules is electrophoretically variable (referred to as DR beta 1), and the other (DR beta 2) migrates constantly among DR2 subtypes. We have constructed cDNA libraries from Dw12 and FJO homozygous typing cells (HTC DHO for Dw12 and HTC FJO for FJO) and isolated DR beta cDNA clones. Four of these clones (FJO-13, DHO-8, FJO-6, and DHO-7) were sequenced, and the deduced amino acid sequences were compared with each other and with two published amino acid sequences for the DR beta molecules derived from a DR2-Dw2HTC. Prediction of the migration patterns on 2D-PAGE from the amino acid sequences of these and other DR beta molecules allows the tentative designation of the two full-length cDNA (DHO-8 and FJO-13) as coding for DR beta 2 molecules and the other two cDNA (DHO-7 and FJO-6) for DR beta 1 molecules. Amino acid sequence comparisons also show that the constantly migrating DR beta 2 molecules, as well as the electrophoretically variable DR beta 1 molecules, from Dw2, Dw12, and FJO have different primary amino acid sequences, including a clustered difference in the third hypervariable region of the polymorphic first domain.

Comparison of DR beta 1 alleles from diabetic and normal individuals

Insulin-dependent diabetes (IDD) is positively associated with HLA-D proteins. A critical question is whether or not sequence differences within the HLA-D coding region are the same or different in diabetics and normal individuals of the same haplotype. We have isolated both DR beta 1 alleles from a Dw4/LD MN2 cDNA library and compared them to DR beta 1 genes isolated from normal individuals of the same Dw phenotype. We found no nucleotide differences in the coding region between the normal and diabetic alleles of DR beta 1 suggesting to us that DNA differences other than the DR beta 1 coding region may account for the observed association of HLA-D and diabetes.

cDNA cloning and sequencing reveals that the electrophoretically constant DR beta 2 molecules, as well as the variable DR beta 1 molecules, from HLA-DR2 subtypes have different amino acid sequences including a hypervariable region for a functionally important epitope

Two-dimensional gel electrophoresis (2D-PAGE) of DR molecules from three different Dw subtypes (Dw2, Dw12, and FJO) of the HLA-DR2 haplotype reveals that at least two DR beta genes are expressed. Protein mixing experiments demonstrate that one of the two expressed DR beta molecules is electrophoretically variable (referred to as DR beta 1), and the other (DR beta 2) migrates constantly among DR2 subtypes. We have constructed cDNA libraries from Dw12 and FJO homozygous typing cells (HTC DHO for Dw12 and HTC FJO for FJO) and isolated DR beta cDNA clones. Four of these clones (FJO-13, DHO-8, FJO-6, and DHO-7) were sequenced, and the deduced amino acid sequences were compared with each other and with two published amino acid sequences for the DR beta molecules derived from a DR2-Dw2HTC. Prediction of the migration patterns on 2D-PAGE from the amino acid sequences of these and other DR beta molecules allows the tentative designation of the two full-length cDNA (DHO-8 and FJO-13) as coding for DR beta 2 molecules and the other two cDNA (DHO-7 and FJO-6) for DR beta 1 molecules. Amino acid sequence comparisons also show that the constantly migrating DR beta 2 molecules, as well as the electrophoretically variable DR beta 1 molecules, from Dw2, Dw12, and FJO have different primary amino acid sequences, including a clustered difference in the third hypervariable region of the polymorphic first domain.

Estrogen binding protein activity in Morris hepatoma 7777 compared with normal rat liver

Estrogen binding protein activities were determined in the cytosol from adult male Buffalo rat liver and Morris hepatoma 7777. Estrogen receptors were prepared using the protamine sulfate precipitation technique of Chamness. The ability of various unlabeled steroids competing with [3H]estradiol was examined to establish the binding specificity. Estradiol binding in Morris hepatoma 7777 cytosol was greatly decreased compared with that present in hepatic cytosol prepared from normal rat liver. The receptor concentration expressed as femtomoles per milligram of cytoplasmic protein was 31.1 +/- 2.9 SD for normal rat liver and 0.41 +/- 0.88 SD for the hepatoma. Gel filtration chromatography revealed the presence of an estrogen binder in hepatoma cytosol which was not present in either normal liver or in the protamine sulfate precipitates of hepatoma cytosol. The molecular weight, binding specificity, and precipitation of this protein by specific antiserum suggests that it is alpha-fetoprotein.

Induction of hepatocyte stimulating activity by T3 and appearance of the activity despite inhibition of DNA synthesis by adriamycin

A hepatocyte stimulating activity (HSA) has been extracted from rats that had received an injection of a pharmacological dose of T3 20 hours earlier. The injection of HSA from T3-treated rats into different recipient rats that had previously had 40% of their liver removed resulted in a significant increase in hepatic DNA synthesis. The injection of saline or HSA from normal rat liver had little or no effect on hepatic DNA synthesis in recipient rats. HSA from the T3-treated rats also stimulated DNA synthesis in Novikoff hepatoma cells and primary hepatocytes in culture, and in isolated normal rat liver nuclei in a nuclear incorporating system. In further experiments in which the increased DNA synthesis that follows partial hepatectomy was blocked by adriamycin, HSA appeared in these non-regenerating livers. This latter observation had indicated that the development of HSA is not merely an accompaniment of DNA synthesis.