Proportion of solvent-exposed amino acids in a protein and rate of protein evolution

Translational selection, including gene expression, protein abundance, and codon usage bias, has been suggested as the single dominant determinant of protein evolutionary rate in yeast. Here, we show that protein structure is also an important determinant. Buried residues, which are responsible for maintaining protein structure or are located on a stable interaction surface between 2 subunits, are usually under stronger evolutionary constraints than solvent-exposed residues. Our partial correlation analysis shows that, when whole proteins are included, the variance of evolutionary rate explained by the proportion of solvent-exposed residues (P(exposed)) can reach two-thirds of that explained by translational selection, indicating that P(exposed) is the most important determinant of protein evolutionary rate next only to translational selection. Our result suggests that proteins with many residues under selective constraint (e.g., maintaining structure or intermolecular interaction) tend to evolve slowly, supporting the "fitness (functional) density" hypothesis.

Motor equivalent control of the center of mass in response to support surface perturbations

To claim that the center of mass (CM) of the body is a controlled variable of the postural system is difficult to verify experimentally. In this report, a new variant of the method of the uncontrolled manifold (UCM) hypothesis was used to evaluate CM control in response to an abrupt surface perturbation during stance. Subjects stood upright on a support surface that was displaced in the posterior direction. Support surface translations between 0.03 and 0.12 m, each lasting for 275 ms, were presented randomly. The UCM corresponding to all possible combinations of joints that are equivalent with respect to producing the average pre-perturbation anterior-posterior position of the center of mass (CM(AP)) were linearly estimated for each trial. At each point in time thereafter, the difference between the current joint configuration and the average pre-perturbation joint configuration was computed. This joint difference vector was then projected onto the pre-perturbation UCM as a measure of motor equivalence, and onto its complementary subspace, which represents joint combinations that lead to a different CM(AP) position. A similar analysis was performed related to control of the trunk's spatial orientation. The extent to which the joint velocity vector acted to stabilize the CM(AP) position was also examined. Excursions of the hip and ankle joints both increased linearly with perturbation magnitude. The configuration of joints at each instance during the perturbation differed from the mean configuration prior to the perturbation, as evidenced by the joint difference vector. Most of this joint difference vector was consistent, however, with the average pre-perturbation CM(AP) position rather than leading to a different CM(AP )position. This was not the case, however, when performing this analysis with respect to the UCM corresponding to the control of the pre-perturbation trunk orientation. The projection of the instantaneous joint velocity vector also was found to lie primarily in the UCM corresponding to the pre-perturbation CM(AP) position, indicating that joint motion was damped in directions leading to a change away from the pre-perturbation CM(AP) position. These results provide quantitative support for the argument that the CM position is a planned variable of the postural system and that its control is achieved through selective, motor equivalent changes in the joint configuration in response to support surface perturbations. The results suggest that the nervous system accomplishes postural control by a control strategy that considers all DOFs. This strategy presumably resists combinations of DOFs that affect the stability of important task-relevant variables (CM(AP) position) while, to a large extent, freeing from control combinations of those DOFs that have no effect on the task-relevant variables (Schöner in Ecol Psychol 8:291-314, 1995).

Primary dysmenorrhea and risk of preterm delivery

Little is known about the mechanism and biochemical pathway of preterm delivery. Some drugs used to treat preterm labor are also useful for the treatment of primary dysmenorrhea. This study attempted to evaluate the association between primary dysmenorrhea and preterm delivery from an epidemiological perspective. A nested case-control study was conducted; 329 singleton preterm delivery cases were investigated, in aggregate and in subgroups (spontaneous preterm labor and preterm premature rupture of membranes). Concurrently, 329 singleton gravid women with term delivery served as controls. Medical charts and records provided information about the maternal history of dysmenorrhea, index pregnancy outcome, and demographic characteristics. Adjusted odds ratios (ORs) and 95% confidence intervals (CIs) were calculated using the multiple logistic regression method. Gravid women with a history of primary dysmenorrhea had no more risk of preterm delivery than those without a history of primary dysmenorrhea (adjusted OR, 1.16; 95% CI, 0.95 to 2.19; p=0.37). However, for subgroup analysis, gravid women with severe primary dysmenorrhea were associated with an adjusted 2.73-fold risk of spontaneous preterm delivery (95% CI, 1.49 to 4.95; p=0.02), and with an adjusted 1.51-fold risk of preterm premature rupture of membranes (95% CI, 0.68 to 3.22; p=0.31). Severe primary dysmenorrhea is associated with an increased risk of spontaneous preterm delivery. A common pathophysiologic pathway may exist between these two disorders. Further in-depth biochemical and molecular studies are necessary to explore this phenomenon.

Potential role of preoperative serum CA125 for the differential diagnosis between uterine leiomyoma and uterine leiomyosarcoma

PURPOSE

Most comparisons between uterine leiomyoma and uterine leiomyosarcoma have been based on postoperative pathological or molecular analyses. Very few reports have investigated preoperative differentiation between uterine leiomyoma and uterine leiomyosarcoma.

METHODS

Between January 1990 and December 2003, 42 consecutive patients with uterine leiomyosarcoma treated at index hospitals were analyzed. Meanwhile, 84 patients with uterine leiomyomas were used as controls. The diagnostic performance of preoperative serum CA125 for the differential diagnosis between uterine leiomyoma and uterine leiomyosarcoma using receiver operating characteristic (ROC) curves was evaluated. Data presentations were categorized into premenopausal and postmenopausal groups. Diagnostic efficiency was calculated as the sensitivity multiplied by the specificity.

RESULTS

Values of preoperative serum CA125 were significantly higher in the uterine leiomyosarcoma group than those in the uterine leiomyoma group. There was significant overlapping of preoperative serum CA125 between the uterine leiomyoma group and early-stage uterine leiomyosarcoma. For both the premenopausal and postmenopausal group, there was a significant difference in the distribution of preoperative serum CA125 in early-stage and advanced-stage uterine leiomyosarcoma. The optimal cutoff values of serum CA125 for the premenopausal group and postmenopausal group was 162 U/mL and 75 U/mL, respectively.

CONCLUSION

These findings demonstrated that preoperative serum CA125 had a potential role in the differential diagnosis between early-stage and advanced-stage uterine leiomyosarcoma. Further investigation with a larger sample size at adequate power is necessary to verify the current study.

Effects of the dietary phytoestrogen biochanin A on cell growth in the mammary carcinoma cell line MCF-7

Studies of the dietary phytoestrogen biochanin A on cell proliferation of the cultured estrogen responsive cells human breast carcinoma MCF-7 showed that biochanin A exhibits biphasic regulation on MCF-7 cells. At concentrations of less than 10 microg/mL, cells respond to biochanin A by increasing cell growth and de novo DNA synthesis. The addition of biochanin A at concentrations of greater than 30 microg/mL significantly inhibited cell growth and DNA synthesis in a dose-dependent fashion, resulting in an IC(50) value of 40 microg/mL. The reversibility of these inhibitory effects by biochanin A appears also to be concentration dependent. Cells previously treated with high concentrations (>60 microg/mL) of biochanin A did not regain normal growth after treatment ceased. Biochanin A was cytostatic at low concentrations (<40 microg/mL) and cytotoxic at higher concentrations. Upon exposure to 100 microg/mL of biochanin A, cell morphology was severely altered, cell volume decreased, and condensation of cell components was clearly noticeable. In addition, biochanin A damaged cell membranes by increasing membrane permeability. These results suggest possible molecular and cellular mechanisms of the action of dietary phytoestrogens on estrogen target cells.

Enrichment enhances the expression of sgk, a glucocorticoid-induced gene, and facilitates spatial learning through glutamate AMPA receptor mediation

We have previously demonstrated that the serum and glucocorticoid-inducible kinase (sgk) gene plays a causal role in facilitating memory performance in rats. Environment enrichment is known to facilitate spatial learning. We therefore examined the effect of enrichment on sgk expression. We also examined the role of sgk in spatial and nonspatial learning and the regulation of sgk expression by activation of different glutamate receptors. Both real-time polymerase chain reaction and Western blot analyses revealed that enrichment training preferentially increased sgk mRNA and protein levels in the hippocampus. Transfection of sgk mutant DNA to the hippocampal CA1 area markedly impaired spatial learning, fear-conditioning learning and novel object-recognition learning in rats, but enrichment training effectively reversed these learning deficits. Meanwhile, S422A mutant DNA transfection prevented enrichment-induced spatial learning facilitation. In studying glutamate receptor regulation of sgk expression, we found that blockade of N-methyl-d-aspartate (NMDA) receptors in general, and the NR2B subunit in particular both effectively blocked enrichment-induced spatial learning facilitation, but they did not block enrichment-induced sgk expression. Upon various glutamate agonist infusions, only alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA) increased sgk mRNA levels significantly in the hippocampus. Furthermore, blockade of AMPA receptors effectively blocked both enrichment-induced spatial learning facilitation and sgk expression. These results indicate that there is a dissociation between NMDA receptor activation and sgk expression. Enrichment enhanced spatial learning through both NMDA and AMPA receptor activation, whereas enrichment-induced sgk expression is specifically mediated through AMPA receptors. These results suggest that sgk could serve as a novel molecular mechanism, in addition to the NMDA receptor NR2B, underlying enrichment-induced learning facilitation.

Dosimetric characteristics of dynamic wedged fields: a Monte Carlo study

We have developed a Monte Carlo (MC) technique using the EGS4/BEAM system to calculate dosimetric characteristics of dynamic wedges (DW) for photon beam radiotherapy. The simulation of DW was accomplished by weighting the history numbers of the electrons, which are incident on the target in accordance with the segmented treatment table. Calculations were performed for DW with wedge angles ranging from 15 degrees to 60 degrees as well as for open fields with different field sizes for both degrees 6 and 18 MV beams. The MC-calculated percentage depth dose (PDD) and beam profiles agreed with the measurements within +/- 2% (of the dose maximum along the beam axis) or +/- 2 mm in high dose gradient region. The DW slightly affects energy spectra of photons and contaminating electrons. These slight changes have no significant effects on PDD as compared to the open field. The MC-calculated dynamic wedge factors agree with the measurements within +/- 2%. The MC method enables us to provide more detailed beam characteristics for DW fields than a measurement method. This beam characteristic includes photon energy spectra, mean energy, spectra of contaminating electrons and effects of moving jaw on off-axis beam quality. These data are potentially important for treatment planning involving dynamic wedges.

Different risks of symptomatic brain necrosis in NPC patients treated with different altered fractionated radiotherapy techniques

PURPOSE

To report our observation of excessive temporal lobe necrosis in nasopharyngeal carcinoma (NPC) patients treated with 160 cGy b.i.d. radiotherapy technique. During the same period, patients treated with 120 cGy b.i.d. have not shown a similar tendency. Our experience may be useful for designing unconventional radiotherapy regimens for NPC patients.

METHODS AND MATERIALS

During the period from October 1991 to January 1998, 81 M0, previously untreated NPC patients completed altered fractionated radiotherapy. Seventy patients were treated with the hyperfractionated technique, and 11 were treated using the accelerated-hyperfractionated scheme. Hyperfractionated radiotherapy was delivered using 120 cGy b.i.d. separated by 6-h intervals throughout the course. A minimum tumor dose of 8000 cGy was the standard dose over an 8-week period. With the accelerated-hyperfractionated scheme, 160 cGy was given twice daily, also with an interval of 6 h. The minimum tumor dose ranged between 6840 and 7640 cGy, with 7 of the 11 patients receiving 7000 cGy. The arrangement of portals was the same for both regimens. The follow-up period for patients alive was from 32 to 102 months with a median of 61 months for the hyperfractionated patients. For the accelerated-hyperfractionated group, it ranged from 67 to 82 months with a median of 72 months. No patient was lost to follow-up.

RESULTS

At the time of analysis, 49 of the 70 patients in the hyperfractionated group were alive. In the accelerated group, 8 of the 11 patients were alive. The estimated radiation dose to the temporal lobe for the hyperfractionated group was 6000-7440 cGy with a median of 7080 cGy. For the accelerated-hyperfractionated group, the dose range was 4480-6700 cGy with a median of 6400 cGy. Of the 70 patients treated with hyperfractionated radiotherapy, none developed symptomatic brain necrosis, despite the higher total dose to the temporal lobe in general. In contrast, 3 of the 11 (27%) patients irradiated using the accelerated-hyperfractionated regimen suffered from temporal lobe necrosis at 16, 19, and 40 months after completion of radiotherapy.

CONCLUSION

An excessive incidence of temporal lobe necrosis was noted when an accelerated-hyperfractionated regimen with 160 cGy b.i.d. was used in NPC patients with a median brain dose of 6400 cGy. There has been no such event in patients treated using a hyperfractionated regimen with 120 cGy and a median brain dose of 7000 cGy. The real causes of this discrepancy are not known. However, a high sensitivity of the human brain to a change in fraction size may play a role.

Human neuron-committed teratocarcinoma NT2 cell line has abnormal ND10 structures and is poorly infected by herpes simplex virus type 1

Herpes simplex virus type 1 (HSV-1) immediate-early regulatory protein ICP0 stimulates the initiation of lytic infection and reactivation from quiescence in human fibroblast cells. These functions correlate with its ability to localize to and disrupt centromeres and specific subnuclear structures known as ND10, PML nuclear bodies, or promyelocytic oncogenic domains. Since the natural site of herpesvirus latency is in neurons, we investigated the status of ND10 and centromeres in uninfected and infected human cells with neuronal characteristics. We found that NT2 cells, a neuronally committed human teratocarcinoma cell line, have abnormal ND10 characterized by low expression of the major ND10 component PML and no detectable expression of another major ND10 antigen, Sp100. In addition, PML is less extensively modified by the ubiquitin-like protein SUMO-1 in NT2 cells compared to fibroblasts. After treatment with retinoic acid, NT2 cells differentiate into neuron-like hNT cells which express very high levels of both PML and Sp100. Infection of both NT2 and hNT cells by HSV-1 was poor compared to human fibroblasts, and after low-multiplicity infection yields of virus were reduced by 2 to 3 orders of magnitude. ICP0-deficient mutants were also disabled in the neuron-related cell lines, and cells quiescently infected with an ICP0-null virus could be established. These results correlated with less-efficient disruption of ND10 and centromeres induced by ICP0 in NT2 and hNT cells. Furthermore, the ability of ICP0 to activate gene expression in transfection assays in NT2 cells was poor compared to Vero cells. These results suggest that a contributory factor in the reduced HSV-1 replication in the neuron-related cells is inefficient ICP0 function; it is possible that this is pertinent to the establishment of latent infection in neurons in vivo.

Progesterone receptor gene expression in preimplantation pig embryos

OBJECTIVE

It is not known whether progesterone, which plays a key role in establishing and maintaining pregnancy, acts directly on embryos or indirectly through the mother's reproductive tract. Since the physiological effects of progesterone are mediated by progesterone receptors (PR), the expression of PR during the preimplantation stages of pig embryos was determined.

DESIGN AND METHODS

Preimplantation pig embryos at different developmental stages were examined using reverse transcription-polymerase chain reaction techniques for the purpose of determining PR gene expression. Immunocytochemistry procedures were used to determine whether PR mRNA is translated into PR protein in preimplantation embryos.

RESULTS

PR mRNA was found in pig embryos at the two-cell stage, but levels started to decline at the four-cell stage; none was detected at the five- to eight-cell stage, nor at any time during the morula and blastocyst stages. Results showed that PR protein was immunostained in pig oocytes and embryos at the 4-cell stage, but that no significant immunostaining occurred during the morula and blastocyst stages.

CONCLUSION

These results indicate that the effects of PR on early embryogenesis appear to be indirect, perhaps via PR-regulated growth-promoting factors produced in the maternal reproductive tract.

Estrogen receptor is expressed in pig embryos during preimplantation development

Although estrogen is recognized as essential for embryonic development and maintenance of pregnancy, it remains unclear whether it has a direct role in the embryos themselves. The aim of this study was to investigate whether estrogen can have any effect in pig embryos during preimplantation development. Since the function of estrogen is mediated through its specific receptor, estrogen receptor (ER), the presence of ER mRNA and protein in pig embryos collected in vivo at different stages of preimplantation development was determined and compared. Using reverse transcription polymerase chain reaction, ER RNA was detected at the one-cell, two-cell, and four-cell stages. The level became undetectable at the five- to eight-cell stages and the morula stages and then reappeared again at the blastocyst stage. To determine whether the ER message observed in the embryos was translated into ER protein, immunocytochemical analysis was performed and the presence of ER protein was detected in oocytes at one-cell and four-cell stages. However, the amount of ER protein in porcine embryos at the blastocyst stage was still below the detection limit. The presence of ER mRNA at the blastocyst stages suggests that estrogen may start to act directly on pig embryos afterwards, and our results provide a basis for determining the direct role of estrogen in preimplantation pig embryos.

A dynamic connection between centromeres and ND10 proteins

ND10, otherwise known as nuclear dots, PML nuclear bodies or PODs, are punctate foci in interphase nuclei that contain several cellular proteins. The functions of ND10 have not been well defined, but they are sensitive to external stimuli such as stress and virus infection, and they are disrupted in malignant promyelocytic leukaemia cells. Herpes simplex virus type 1 regulatory protein Vmw110 induces the proteasome-dependent degradation of ND10 component proteins PML and Sp100, particularly the species of these proteins which are covalently conjugated to the ubiquitin-like protein SUMO-1. We have recently reported that Vmw110 also induces the degradation of centromere protein CENP-C with consequent disruption of centromere structure. These observations led us to examine whether there were hitherto undetected connections between ND10 and centromeres. In this paper we report that hDaxx and HP1 (which have been shown to interact with CENP-C and Sp100, respectively) are present in a proportion of both ND10 and interphase centromeres. Furthermore, the proteasome inhibitor MG132 induced an association between centromeres and ND10 proteins PML and Sp100 in a significant number of cells in the G(2) phase of the cell cycle. These results imply that there is a dynamic, cell cycle regulated connection between centromeres and ND10 proteins which can be stabilised by inhibition of proteasome-mediated proteolysis.

Expression of leukemia inhibitory factor and its receptor in preimplantation embryos

OBJECTIVE

To examine the expression of leukemia inhibitory factor (LIF) and its receptor (LIF-R) transcripts in human and murine preimplantation embryos.

DESIGN

Prospective study.

SETTING

University medical center.

PATIENT(S)

Human oocytes were obtained from patients undergoing IVF treatment. Two-cell murine embryos were obtained from ICR strain mice.

INTERVENTION(S)

Second-day intracytoplasmic sperm injection procedures were performed on oocytes that failed to be fertilized by IVF. Embryos were cultured to various stages and collected for study.

MAIN OUTCOME MEASURE(S)

The transcript levels of LIF and LIF-R in these embryos were examined and semiquantitated using single-cell reverse transcription-polymerase chain reaction methodology.

RESULT(S)

Leukemia inhibitory factor and LIF-R transcripts were detectable in most human preimplantation embryos (30 of 34 and 31 of 34 embryos showed LIF and LIF-R messenger RNA, respectively). There was a trend toward decreased expression of both transcripts in embryos at the four-cell stage and in embryos in which growth had been arrested for 24-48 hours. The expression of LIF and LIF-R genes in murine embryos was inconsistent.

CONCLUSION(S)

Preimplantation human embryos express LIF and LIF-R messenger RNA. It is suggested that LIF may be able to affect embryo development through its action at stages before implantation in an autocrine or paracrine manner.

Calculation of head scatter factors at isocenter or at center of field for any arbitrary jaw setting

The purpose of this work is to calculate the head scatter factors for any arbitrary jaw setting by using two different semi-empirical methods. The head scatter factor at the center of field (COF) for any arbitrary jaw setting can be defined as H(COF)(X1,X2,Y1,Y2,r)=DairCOF(XI1,X2,Y1,Y2,r)/ [Dair(5,5,5,5,0)*OAR(r)], where X1, X2, Y1, and Y2 are the jaw positions; r is the distance between COF and isocenter (IC); OAR(r) is the Off-Axis-Ratio; DairCOF(X1,X2,Y1,Y2,r) is the dose in air measured at COF; Dair(5,5,5,5,0) is the dose in air measured at IC for the 10 x 10 cm2 field. In certain clinical situations, doses are prescribed at IC instead of COF for asymmetric fields. In these cases, head scatter factors should be determined at IC. It is found that the head scatter factors at IC for asymmetric fields [H(IC)(X1,X2,Y1,Y2)] are lower than H(COF)(X1,X2,Y1,Y2,r) for the same jaw setting by up to 4%. The values of H(IC)(X1,X2,Y1,Y2) and H(COF)(X1,X2,Y1,Y2,r) for a variety of jaw settings were measured using a miniphantom of 3-cm diameter for a 6- and a 18-MV photon beams. An equivalent square formula, derived presently at the source plane for any jaw setting, was used to calculate H(COF)(X1,X2,Y1,Y2,r). The calculation and the measurement agree within +/-1% (+/-0.5% for most clinical situations). To calculate H(IC)(X1,X2,Y1,Y2), we have generalized the Day's "quarter-field" method, i.e., H(IC)(X1,X2,Y1,Y2) = [H(X1,X1,Y1,Y1) + H(X1,X1,Y2,Y2) + H(X2,X2,Y1,Y1) + H(X2,X2,Y2,Y2)]/4. We found that the calculation and the measurement agree within +/-0.8% for the beams studied.

Neoadjuvant chemotherapy followed by radiotherapy should not be a standard approach for locally advanced cervical cancer

PURPOSE

To investigate the role of neoadjuvant chemotherapy followed by radiotherapy in locally advanced cervical cancer.

METHODS AND MATERIALS

This study cites all known literature on the subject in the English language. Articles were selected for analysis by MEDLINE and CANCERLINE computer searches. In Phase II trials, the response rates of some selective series were analyzed. However, This article will specially emphasize the result of all Phase III randomized trials.

RESULTS

Several investigators did obtain promising results from Phase II trials of neoadjuvant chemotherapy, mostly cisplatin-based combinations, followed by radiotherapy. However, most Phase III trials failed to demonstrate any benefit in terms of loco-regional relapse and/or survival by up-front chemotherapy.

CONCLUSION

The role of neoadjuvant chemotherapy remains to be defined, and the search for more active new agents must be continued. The neoadjuvant setting is still experimental and could not be recommended as a standard treatment at the present.

Concurrent 5-fluorouracil, daily low-dose cisplatin, and radiotherapy in stage IIIB cervical cancer. A phase II prospective study

Between June 1987 and May 1991, 30 patients with Stage IIIB cervical cancers were treated using synchronous radiotherapy, 5-fluorouracil (5-FU), and daily low-dose cisplatin. External radiotherapy (3,600-3,960 cGy) was given to the whole pelvis in 4 weeks. Two courses of intracavitary brachytherapy were given 2 weeks later. Parametrial boost was then given. Continuous infusion of 5-FU 750 mg/m2 was given for 5 days during the first and third week of pelvic irradiation. Cisplatin (6 mg/m2) was given 30 min before every irradiation in the second and fourth week. The complete response rate was 87%. The 3-year local control rate was 77%. The 3-year overall and disease-free survival rate was 66% and 56%, respectively. Distant metastases were the major causes of treatment failure. Toxicities were acceptable. Our preliminary results indicate that this synchronous combination treatment is feasible. Further follow-up is required to determine whether this regimen has a genuine favorable impact on survival and chronic toxicity.

Twice-per-day fractionated high versus continuous low dose rate intracavitary therapy in the radical treatment of cervical cancer: a nonrandomized comparison of treatment results

PURPOSE

To compare the efficacy of two twice-per-day fractionated high dose rate (HDR) brachytherapies with a historical control group treated with low dose rate (LDR) brachytherapy for cervical cancer patients.

METHODS AND MATERIALS

From 1985 to 1988, 92 patients with cancer of the cervic were treated by remote-controlled, HDR brachytherapy, six fractions of 7 Gy per fraction (42 Gy) at point A (HDR-6). Fifty-seven patients were treated with four fractions of 8 Gy per fraction (32 Gy) at point A (HDR-4). A twice-per-day program was used for all HDR patients by two split courses. As a historical control, treatment results of 259 patients treated with LDR brachytherapy (40 Gy in two split courses) were compared with those of the two HDR regimens. All patients received whole pelvic external irradiation, 36-45 Gy (mostly 40 Gy) before brachytherapy.

RESULTS

Five-year local control rates were not significantly different for the three groups (HDR-6 = 82.0%, HDR-4 = 85.5%, and LDR = 89.5%, respectively). Five-year survival rates were also comparable (67.7%, 77.9%, and 74.1%, respectively). However, late complications were lower in HDR-4 than HDR-6 (11.0% vs. 25.6%).

CONCLUSIONS

Both 5-year local control and survival rates were comparable among the three groups. However, HDR-4, which was more biologically equivalent to our LDR regimen, showed fewer complications compared to HDR-6. In addition, our twice-per-day schedule shortened the hospital stay.

Risk factors of lung cancer by histological category in Taiwan

The relationship between various risk factors and lung cancer by different histological types was evaluated in a case-control study. A total of 72 adenocarcinoma patients and 59 squamous/small cell lung cancer patients, 262 hospital controls and 262 neighborhood controls were interviewed. Multiple conditional logistic regression analyses revealed that occupational exposures to asbestos and working as a cook were significant risk factors associated with adenocarcinoma of the lung. An inverse association between incense burning and the adenocarcinoma was noted. The squamous and small cell carcinomas of the lung were significantly associated with cigarette smoking, passive smoking exposure from friends at entertainment activities, the use of coal as cooking fuel, history of prior tuberculosis and chronic bronchitis, and occupational exposures to asbestos.

A new in vivo assay of the reactions of microencapsulated human tumor cells to chemotherapeutic drugs

A new cell culture modality had already been established in our laboratory. Using this model, living KB and GBM 8401 tumor cells grew and proliferated exponentially in semipermeable microcapsules, implanted in vivo. The culture method was designed as a modality for a predictive anticancer drug sensitivity test. Its advantages included providing a three-dimensional growth and in vivo supply of nutrients. Tumor cell sensitivity to drugs can be assessed in vivo. The assay is applicable to virtually all histological types of human tumor cells. Using this technique, anticancer drug sensitivity tests of KB and GBM 8401 cells were evaluated. The results showed that such encapsulated cells grew and proliferated rapidly. In addition, the proliferation of KB cells was more rapid than that of GBM 8401 cells under conventional monolayer and in vivo microcapsule culture states. They were very sensitive to adriamycin and fluorouracil, and relatively resistant to cyclophosphamide while cultured in vitro. The viability percentage of microencapsulated KB cells cultured in vivo for two weeks was around 80-90%, roughly similar to that of the same cells conventionally cultured in vitro. However, the proliferation rates of encapsulated KB and GBM 8401 cells in vivo were significantly inhibited by all the drugs tested, with KB cells inhibited more significantly than GBM 8401. These results also suggest that some anticancer drugs needing to be bioactivated in vivo had better test results by this technique, and thus false negative results could be excluded. Also, the good repair capacity of microcapsules implanted in vivo, for damaged tumor cells previously incubated with chemotherapeutic drugs, appears to provide a much better environment for cell growth because much essential nourishment can be supplied. The inhibition percentage of fluorouracil to encapsulated cancer cells from patients with adenocarcinoma of the colon was also tested; they were 69.8% in vivo and 76.5% in vitro. This fast, relatively inexpensive in vivo model can be used to screen various anticancer drugs and help clinical oncologists to select the most effective agents for individual patients.