Combinatorial library diversity: probability assessment of library populations

A method is described for measuring the diversity of combinatorial oligonucleotide libraries that entails extrapolating the base composition of a co-synthesized model library (dNC, N = A, C, G, T) to that of a multibase library template. The base composition of dNC was measured by HPLC. The ability of dNC to predict the base composition of a multibase library template was corroborated by measuring the composition of a 12 base combinatorial library. The base composition of the 12 base library was determined by several template dependent incorporation assays: measurement of restriction fragment specific activities from polymerase incorporation/restriction enzyme digests, template directed radionucleotide primer extension and quantitative dideoxynucleotide sequencing. Additionally, a convention for describing oligomeric combinatorial library (OCL) diversity is proposed. The convention uses a quantity termed the diversity quotient (Qd) to describe library breadth and the mole fraction of the least represented monomeric unit of the OCL to calculate minimum library quantity requirements. Similar methods/conventions could presumably be developed/adopted for non-nucleic acid libraries.

Whole blood selenium in exudative age-related maculopathy

PURPOSE

We tested whether exudative ARM was associated with low whole blood levels of selenium (Se).

METHODS

Blood samples, drawn from 10 exudative ARM patients (61.2-76.1 yr) and 9 healthy-eyed (66.9-75.1 yr) subjects, were analyzed by atomic absorption spectroscopy.

RESULTS

Selenium concentration was significantly lower in the ARM group (186.6 microg/l) than in controls (207.0 microg/l). Because many ARM patients took Se supplements, we tested the effect on blood Se of 80 microg per day of sodium selenate. We found no enduring effects of supplementation for healthy-eyed, younger adults.

CONCLUSIONS

Significant group differences in this preliminary study indicate a larger-scale study of blood Se concentration in exudative ARM patients is warranted. If the effect of Se supplementation on the progression of exudative ARM is tested in future trials, it will be important to use organic Se, to identify the components of blood affected, and to observe protocol for at least six months.

Comparison of low molecular weight heparin (Fragmin) with sodium heparin for prophylaxis against postoperative thrombosis in women undergoing major gynaecological surgery

A randomized controlled trial was undertaken comparing the efficacy and safety of low molecular weight (LMW) heparin (Fragmin) with sodium heparin for prophylaxis against postoperative thromboembolic disease after major gynaecological surgery. Women were randomized to receive subcutaneous injections of 5,000 U of either once daily LMW heparin or twice daily sodium heparin. A total of 566 women were recruited, of whom 552 completed the study. Most women (461) had malignant disease and 430 of these underwent radical surgery. The remainder underwent major, but not radical surgery. There were 5 thromboembolic events in the LMW heparin group and 2 in the sodium heparin group, with no significant difference between these groups. No significant difference was found in the incidence of intraoperative or postoperative transfusion in the 2 groups. The decision of which heparin to use in routine practice cannot be made on clinical grounds.

Prognostic significance of mammographic detection in a cohort of conservatively treated breast cancer patients

PURPOSE

This study aimed to evaluate the prognostic significance of nonpalpable mammographically detected breast cancer in a cohort of conservatively treated breast cancer patients.

METHODS AND MATERIALS

The records of 953 patients with invasive stage I and II breast cancer treated with conservative surgery and radiation therapy prior to January 1990 were reviewed. Mode of presentation with reference to clinical and mammographic findings was recorded. For statistical analysis, patients were divided into two groups: 748 patients presented with clinically palpable masses with or without mammographic abnormalities (PALP), and 205 presented with nonpalpable mammographically detected tumors (MGDET).

RESULTS

Patients in the MGDET group presented with cancers at earlier stages of disease, had tumors of smaller pathological size, were more often hormone-receptor positive, and less frequently required adjuvant systemic therapy. As of December 1995, with a median follow-up of 11.6 years, the MGDET group had a higher 10-year overall survival rate (82% vs 68%) and a superior 10-year distant-metastasis-free rate (87% vs 75%). The ipsilateral breast tumor relapse rate was similar between the PALP and MGDET groups. When broken down by age (< 50 years vs > or = 50 years), the benefits of early detection remained apparent with a statistically significant superior distant-metastasis-free rate in women under age 50 in the MGDET group compared with women under age 50 in the PALP group. In a multivariate analysis, mammographic detection remained an independent prognostic factor for distant-metastasis-free survival.

CONCLUSION

Patients presenting with nonpalpable mammographically detected invasive breast cancer have a favorable prognosis compared with their counterparts presenting with clinically palpable masses. Although the issue of lead-time bias cannot be addressed adequately in this retrospective review, the favorable prognosis with respect to disease-free survival and breast conservation is quite evident. The high probability of disease-free survival and breast preservation in these patients should further encourage the widespread using of screening mammography and the increased use of breast-conserving surgery with radiation therapy.

Are we telling patients enough? A pilot study to assess patient information needs in a gastroenterology outpatient department

OBJECTIVE

To define whether gastroenterology patients wish to receive more information concerning many aspects of their illness and to elicit their attitude after receiving written communication from their hospital practitioner.

METHODS

In stage 1, 73 gastroenterology patients were interviewed and completed a structured questionnaire after their hospital outpatient visit, to assess whether they would like to receive more information about their condition. Stage 2 involved posting a copy of the general practitioner's letter, dictated in the clinic, to the patient and assessing their opinion of its value, by using a second questionnaire. In stage 3 a group of outpatients received a letter specifically prepared for them which summarized the outcome of their clinic visit (with avoidance of medical terms) and they again completed a questionnaire.

RESULTS

More than 75% of patients wished to receive written communication from their hospital practitioner. Ninety percent wanted to know more about diagnostic tests and 92% requested more information about their medication. Ninety percent of patients who received a copy of their GP's letter claimed to understand its contents and felt it was beneficial. Ninety four percent wanted the service to continue. However, there was no advantage in preparing a special letter for patients compared with a simple copy of that sent to their GP.

CONCLUSION

There is considerable interest amongst gastroenterology patients concerning their diagnosis and the management of their disease. The provision of simplified letters about their outpatient management does not seem to have any advantage over simply providing copies of all relevant correspondence sent to GPs.

Low proportion of BRCA1 and BRCA2 mutations in Finnish breast cancer families: evidence for additional susceptibility genes

One hundred breast and breast-ovarian cancer families identified at the Helsinki University Central Hospital in southern Finland and previously screened for mutations in the BRCA2 gene were now analyzed for mutations in the BRCA1 gene. The coding region and splice boundaries of BRCA1 were analyzed by protein truncation test (PTT) and heteroduplex analysis (HA)/SSCP in all 100 families, and 70 were also screened by direct sequencing. Contrary to expectations based on Finnish population history and strong founder effects in several monogenic diseases in Finland, a wide spectrum of BRCA1 and BRCA2 mutations was found. In the BRCA1 gene, 10 different protein truncating mutations were found each in one family. Six of these are novel Finnish mutations and four have been previously found in other European populations. Six different BRCA2 mutations were found in 11 families. Altogether only 21% of the breast cancer families were accounted for by mutations in these two genes. Linkage to both chromosome 17q21 (BRCA1) and 13q12 (BRCA2) was also excluded in a subset of seven mutation-negative families with four or more cases of breast or ovarian cancer. These data indicate that additional breast and breast-ovarian cancer susceptibility genes are likely to be important in Finland.

The views of medical students and junior doctors on pre-graduate clinical teaching

A total of 277 third and fourth year medical students and 304 house officers and senior house officers were asked to prioritise the content and methods of clinical teaching. Response rates were poor, but similar to that in market surveys. Bedside teaching and medical clerking were considered the most valuable methods of teaching and training in practical procedures such as venepunctures and urinary catheterisation was seen as valuable. The design of new curricula in medical education will need to accommodate the views of its clients.

BRCA1 sequence analysis in women at high risk for susceptibility mutations. Risk factor analysis and implications for genetic testing

CONTEXT

A mutation in the BRCA1 gene may confer substantial risk for breast and/or ovarian cancer. However, knowledge regarding all possible mutations and the relationship between risk factors and mutations is incomplete.

OBJECTIVES

To identify BRCA1 mutations and to determine factors that best predict presence of a deleterious BRCA1 mutation in patients with breast and/or ovarian cancer.

DESIGN

A complete sequence analysis of the BRCA1 coding sequence and flanking intronic regions was performed in 798 women in a collaborative effort involving institutions from the United States, Italy, Germany, Finland, and Switzerland.

PARTICIPANTS

Institutions selected 798 persons representing families (1 person for each family) thought to be at elevated a priori risk of BRCA1 mutation due to potential risk factors, such as multiple cases of breast cancer, early age of breast cancer diagnosis, and cases of ovarian cancer. No participant was from a family in which genetic markers showed linkage to the BRCA1 locus.

MAJOR OUTCOME MEASURES

Sequence variants detected in this sample are presented along with analyses designed to determine predictive characteristics of those testing positive for BRCA1 mutations.

RESULTS

In 102 women (12.8%), clearly deleterious mutations were detected. Fifty new genetic alterations were found including 24 deleterious mutations, 24 variants of unknown significance, and 2 rare polymorphisms. In a subset of 71 Ashkenazi Jewish women, only 2 distinct deleterious mutations were found: 185delAG in 17 cases and 5382insC in 7 cases. A bias in prior reports for mutations in exon 11 was revealed. Characteristics of a patient's specific diagnosis (unilateral or bilateral breast cancer, with or without ovarian cancer), early age at diagnosis, Ashkenazi Jewish ethnicity, and family history of cancer were positively associated with the probability of her carrying a deleterious BRCA1 mutation.

CONCLUSIONS

Using logistic regression analysis, we provide a method for evaluating the probability of a woman's carrying a deleterious BRCA1 mutation for a wide range of cases, which can be an important tool for clinicians as they incorporate genetic susceptibility testing into their medical practice.

Tubal sterilisation, hysterectomy and decreased risk of ovarian cancer. Survey of Women's Health Study Group

We have examined the effect of tubal sterilisation and hysterectomy on risk of ovarian cancer in a large case-control study in eastern Australia involving 824 women aged 18-79 years, diagnosed with epithelial ovarian cancer between 1990 and 1993, and 855 controls randomly selected from the electoral roll. Relative risks for ovarian cancer were estimated using multiple categorical regression to adjust for age, parity, oral contraceptive use and other risk factors. Tubal sterilisation was associated with a 39% reduction in risk of ovarian cancer (RR 0.61, 95% CI 0.46-0.85) and hysterectomy with a 36% reduction (RR 0.64, 95% CI 0.48-0.85). Risk remained low 25 years after surgery and was reduced irrespective of sterilisation technique, and estimates were similar among various types of epithelial ovarian cancer. The greatest reduction (74%) was observed among women with primary peritoneal tumours. Pelvic infection and use of vaginal sprays or contraceptive foams were not related to ovarian cancer, while use of talc in the perineal region slightly but significantly increased risk among women with patent fallopian tubes. Reportedly heavy or painful menses, perhaps associated with retrograde flow, were associated with ovarian cancer, and reduction in risk of disease after hysterectomy was greatest among women who had heavy periods. Our findings support the theory that contaminants from the vagina, such as talc, and from the uterus, such as endometrium, gain access to the peritoneal cavity through patent fallopian tubes and may enhance the malignant transformation of ovarian surface epithelium. Surgical tubal occlusion may reduce the risk of ovarian cancer by preventing the access of such agents.

Developing and evaluating a Spanish TEL-MED message on breast cancer

A Spanish TEL-MED message on breast cancer was designed for Delaware. The message, created from a focus group of Latino professionals and volunteers from the American Cancer Society, Delaware Division, provides information for Latinas on breast cancer. In one minute, forty-five seconds the message answers in Spanish the following questions: (1) What are the symptoms of breast cancer? (2) What can women do to protect themselves against breast cancer? (3) What is a mammogram? (4) When should I have a mammogram done? (5) How much does a mammogram cost? The message also provides information on where to obtain low cost or free mammograms. A pamphlet in Spanish, featuring a picture of an elderly Latina listening to the phone message, describes how to access the tape. The message targets older Latinas who prefer to speak Spanish. The American Cancer Society, Delaware Division, distributed a press release featuring the Spanish TEL-MED and circulated the pamphlets to Latino organizations and churches. Evaluation of the TEL-MED message in Spanish suggests it to be an innovative way to reach older Latino women. The Spanish message on breast cancer was requested 58% as often as the breast cancer message in English, and 193% more often than the epilepsy tape in Spanish. The peak period for the calls to the Spanish TEL-MED message occurred after the initial promotional activities. These findings suggest that education of older Latinas on breast cancer can be augmented by the use of TEL-MED message in Spanish. They further suggest that the combination of TEL-MED and mass media campaign had a positive effect on Spanish speaking users of the TEL-MED.

Are cancers of the salivary gland increasing? Experience from Connecticut, USA

BACKGROUND

Recent studies indicate that cancers of the salivary gland are increasing, and the factors responsible for the increase are unknown. Artefactual changes, such as shift in classifying cancers of the floor of the mouth to cancers of the salivary gland, could affect the time trend for salivary gland cancer.

METHODS

The current study examined the time trends for cancers of the salivary gland and for cancers of the floor of the mouth and lower gum by using Connecticut Tumor Registry data for the time period 1935-1992. A regression model was used to identify the components of birth cohort, period and age as determinants of the observed time trend.

RESULTS

Cancers of the salivary gland have recently increased in Connecticut, with a relative risk of 1.48 (95% CI: 1.06-2.08) for females in 1990-1992 compared to 1980-1984, and a comparable relative risk of 1.60 (95% CI: 1.16-2.22) for males. The increase was found in all age groups 40 and over, particularly among those aged 70 and over. The results from age-period-cohort modelling show a recent upturn in the trend for period slopes, with no clear increase from recent birth cohorts, which is consistent with the results from univariate analyses suggesting no clear increase among those under 40 years of age.

CONCLUSION

Our results suggest that artifactual changes, such as a shift in designation of cancer sites, increasing use of the needle aspirate biopsies, and greater access to medical care for the elderly, may have largely contributed to the rising trend. The known risk factors, radiation exposure and a history of a prior cancer, can hardly explain the observed increase. The Epstein-Barr virus infection has only been associated with certain types of rare squamous cell carcinomas of the salivary gland in the Eskimo population. The AIDS epidemic also cannot explain why older age groups have accounted for most of the increase in incidence of the disease. An examination of the incidence rates for cancers of the salivary gland from other populations may help to clarify the issue.

Rare mutations and no hypermethylation at the CDKN2A locus in epithelial ovarian tumours

The tumour-suppressor gene CDKN2A (p16, MTS1, CDK4I) encodes a cell cycle-regulatory protein and is located on chromosome 9p21, a region deleted in a wide variety of human cancers. To determine the role of the CDKN2A gene in the development of ovarian adenocarcinomas, we examined a large series of benign, low malignant potential (LMP) and invasive ovarian neoplasms for evidence of loss of heterozygosity (LOH), homozygous deletions, point mutations and hypermethylation of the CDKN2A locus. We have previously reported LOH on 9p in 45% of malignant ovarian neoplasms and a smaller percentage of benign and LMP tumours. In the current study, 6 malignant tumours were identified with partial deletions of 9p21. In 5 of these, the CDKN2A gene lays within the minimal deleted region. Homozygous deletions of CDKN2A were observed in only 2/88 invasive ovarian tumours and in 5/11 ovarian cancer cell lines. Of 15 primary ovarian tumours analyzed, one nonsense mutation was identified in a mucinous LMP tumour. No evidence of hypermethylation of the CDKN2A gene was found in 50 primary ovarian adenocarcinomas nor in 3 ovarian cancer cell lines. In conclusion, homozygous deletions, mutations and the de novo methylation of 5' CpG island are not frequent modes of inactivation of the CDKN2A gene in ovarian cancer. The target of 9p LOH in ovarian adenocarcinomas is therefore unknown.

Analysis of loss of heterozygosity and KRAS2 mutations in ovarian neoplasms: clinicopathological correlations

The molecular events that give rise to ovarian epithelial neoplasms are not well understood. In particular, it is not known whether adenocarcinomas arise from benign or low malignant potential (LMP) precursors. We have examined a large series of benign (25) and LMP (31) ovarian tumors for loss of heterozygosity (LOH) at multiple loci on 17 chromosomes. LOH was observed in benign tumors on chromosomes 6 (14%) and 9 (5%) and on the X chromosome (33%) only. LOH on these chromosomes was also detected in a small number of LMP neoplasms, suggesting that these may derive sometimes from benign precursors. In addition, we examined LOH in 93 adenocarcinomas. Analysis of associations between LOH events showed that LOH on chromosomes 5 and 17 (P = 0.0002) and on chromosomes 17 and 18 (P = 0.00007) were associated significantly with each other, which suggests that these may represent cooperative, progressive events. No novel significant associations were identified between LOH events and stage, grade, or histology, which would indicate the existence of genetic heterogeneity in ovarian neoplasms. KRAS2 mutations were detected more often in LMP neoplasms than in malignant tumors (P = 0.004) and were detected more often in Stage I/II malignant tumors than in Stage III/IV malignant tumors (P = 0.033), suggesting that LMP tumors with KRAS2 mutations are unlikely to progress to frank malignancy. Univariate (but not multivariate) survival analysis showed that LOH of chromosomes 11 (P = 0.039) and 17 (P = 0.04) was associated with a significantly worse prognosis. Replication of these novel findings is necessary, and the identification, isolation, and characterization of the critical genes affected by LOH will determine their importance in the pathogenesis of ovarian malignancies.

Reappraisal of the role of axillary lymph node dissection in the conservative treatment of breast cancer

PURPOSE

The purpose of this study was (1) to review systemic therapy practice patterns to assess how information regarding nodal status currently influences systemic therapy decisions, and (2) to review long-term outcome of patients who do not undergo axillary dissection compared with patients who do.

METHODS AND MATERIALS

For the current practice patterns portion of the study, the records of 292 patients who presented in the past 3 years with invasive breast cancer and underwent conservative surgery were reviewed to determine systemic therapy administered with respect to patient age, primary tumor size, clinical nodal status, and presenting symptoms. For the long-term outcome portion of the study, the records of 955 patients with invasive breast cancer who underwent conservative surgery and radiation therapy before December 1989 were reviewed. Patient characteristics and outcome of those patients who underwent axillary dissection (n = 565, 59%) were compared with a cohort of patients treated during the same era who did not undergo axillary dissection (n = 390, 41%).

RESULTS

For the current practice-patterns cohort, information regarding nodal status appeared to influence adjuvant systemic therapy for those patients less than 50 years of age and for those patients with palpable masses who were older than 50. Patients older than 50 with nonpalpable mammographically detected tumors have a low probability of nodal involvement and information regarding nodal status rarely changed therapy in this group of patients. In the long-term outcome study, there were no significant differences in the rates of distant metastasis, disease-free survival, or overall survival between those patients who underwent lymph node dissection and those who did not.

CONCLUSION

For selected patients, axillary lymph node dissection appears to have little influence on subsequent management and long-term outcome. These data suggest that it is time to reassess the role of axillary lymph node dissection in patients who undergo conservative surgery and radiation therapy.

Nonlinear propagation applied to the improvement of resolution in diagnostic medical ultrasound

Medical B-mode scanners operating under conditions typically encountered during clinical work produce ultrasonic wave fields that undergo nonlinear distortion. In general, the resulting harmonic beams are narrower and have lower sidelobe levels than the fundamental beam, making them ideal for imaging purposes. This work demonstrates the feasibility of nonlinear harmonic imaging in medical scanners using a simple broadband imaging arrangement in water. The ultrasonic system comprises a 2.25-MHz circular transducer with a diameter of 38 mm, a membrane hydrophone, also with a diameter of 38 mm, and a polymer lens with a focal length of 262 mm. These components are arranged coaxially giving an imaging geometry similar to that used in many commercial B-scanners, but with a receiver bandwidth sufficient to record the first four harmonics. A series of continuous wave and pulse-echo measurements are performed on a wire phantom to give 1-D transverse pressure profiles and 2-D B-mode images, respectively. The reflected beamwidths wn decrease as wn/W1 = 1/n0.78, where n is the harmonic number, and the reflected sidelobe levels fall off quickly with increasing n. In imaging terms, these effects correspond to a large improvement in lateral resolution and signal-to-clutter ratio for the higher harmonics.

Allelic loss on chromosome 7q in ovarian adenocarcinomas: two critical regions and a rearrangement of the PLANH1 locus

The presence of a tumour suppressor gene on chromosome 7q is indicated by cytogenetic, loss of heterozygosity (LOH) and chromosome transfer studies. One candidate gene in this region is Plasminogen Activator Inhibitor-1 (PAI-1). The PAI-1 gene product is involved in proteolysis and may therefore influence tumour spread and invasion. We have analysed a series of 139 ovarian epithelial tumours at four loci in the region 7q21-q31 which includes the PAI-1 gene. The highest rates of loss were found in malignant tumours (FIGO stages I-IV) at markers D7S471 (38%, 20/52 informative cases) and D7S522 (34%, 15/44). No loss was seen in benign tumours and only one out of 27 (4%) informative LMP tumours demonstrated LOH. The smallest region of overlap (SRO) lies between D7S471 and PAI-1. We also identified a rearrangement in one tumour in the PAI-1 gene, suggesting that this may be the inactivated gene in this region. In addition LOH at the more distal marker, D7S522, which lies outside the SRO, shows significant association with stage (P=0.0343) and with LOH on chromosome 13 (P=0.0024). This is in contrast to all other markers examined. These data suggest the presence of two critical regions on 7q which may be important in subsets of epithelial ovarian tumours.

Type IIS restriction enzyme footprinting I. Measurement of a triple helix dissociation constant with Eco57I at 25 degrees C

A method is described to measure triple helix dissociation constants by inhibiting the cleavage of a plasmid constructed to contain a target sequence for the triplex forming oligonucleotide (TFO) dT20 by the type IIS restriction enzyme Eco57I. The method relies upon the TFO's ability to block the cleavage reaction by occupying the enzymes cleavage site but not its specific binding sequence. Using this protocol, the dissociation constant for dT20 bound to its target was 0.16 +/- 0.01 microM at 25 degrees C. The accuracy of this experiment was demonstrated by measuring the Kd of an affinity cleavage TFO using Eco57I and Quantitative Affinity Cleavage Titration. Type IIS restriction endonuclease footprinting should be useful for the qualitative and quantitative investigation of ligand-DNA interactions.

A comparison of measured and calculated single- and double-stranded oligodeoxynucleotide extinction coefficients

The hyperchromicity resulting from exhaustive hydrolysis of several single-stranded and double-stranded oligodeoxynucleotides (ODN) with snake venom phosphodiesterase or snake venom phosphodiesterase/DNase I was used to measure the ODN's extinction coefficient at 260 nm. These extinction coefficients were compared with those obtained using nonempirical approximations. For the oligodeoxynucleotides investigated, the nonempirical approximations yielded extinction coefficients within 20% of the measured values.

Mental health concerns of Canadian adolescents: a consumer's perspective

OBJECTIVE

To evaluate the mental health of adolescent students in Metropolitan Toronto.

METHOD

A survey was developed by adolescents for adolescents to evaluate adolescent mental health. The survey was completed by 486 secondary school students in Metropolitan Toronto.

RESULTS

The findings of this consumer-directed survey show that the majority of teenagers are not overwhelmed by stress and generally exhibit healthy coping behaviours. Violence is identified as an important concern and help-seeking behaviour for mental health issues, when it occurs, is directed primarily towards the family and teachers rather than physicians.

CONCLUSION

A number of important issues regarding mental illness, including its identification and treatment, were not considered by teens to be part of their mental health concerns. The implications of these findings for the development of community-based mental health programs for adolescents are discussed.

Small cell carcinoma of the cervix of neuroendocrine origin causing obstructed labour

Small cell carcinoma of the cervix complicating pregnancy is rare, only 4 cases having been reported. This is the first case in which the tumour is reported as causing obstructed labour.

Ipsilateral breast tumor recurrence as a predictor of distant disease: implications for systemic therapy at the time of local relapse

PURPOSE

To evaluate the prognostic significance of ipsilateral breast tumor recurrence (IBTR) with respect to the subsequent development of distant metastasis.

MATERIALS AND METHODS

Between January 1970 and December 1989, 973 patients with invasive breast cancer were treated with conservative surgery and radiation therapy at Yale-New Haven Hospital. The median follow-up time as of December 1993 was 8.6 years. A number of prognostic factors were tested as possible predictors of distant metastases, including whether a patient experienced IBTR. IBTRs were broken down by time to recurrence to determine whether the breast recurrence-free interval had any prognostic relevance with respect to the development of distant metastasis.

RESULTS

As of December 1993, out of the entire population of 973 patients, 73 patients had developed IBTR and 134 had developed distant metastases. The overall actuarial survival rate at 10 years was .71 +/- .02, with a 10-year actuarial breast recurrence-free rate of .84 +/- .02 and a 10-year distant metastasis-free rate of .77 +/- .02. The overall distant metastasis rate was higher in patients who experienced IBTR compared with patients who had never experienced IBTR. Furthermore, the time to IBTR had a significant effect on distant metastases. Of 32 patients who developed an IBTR within 4 years of original diagnosis, 16 (50%) developed distant metastases. In contrast, of 41 patients who developed later breast relapses (> 4 years from original diagnosis), only seven (17%) developed distant metastases (P < .01). Of 32 patients who developed early breast relapse, the 5-year survival rate following breast relapse was .50 +/- .01, compared with a 5-year post-breast relapse survival rate of .78 +/- .10 among 41 patients with later breast relapses (P < .05).

CONCLUSION

It appears that early IBTR is a significant predictor for distant metastases. Whether early breast tumor relapse is a marker for or cause of distant metastases remains a controversial and unresolved issue. Implications for adjuvant systemic therapy at the time of breast relapse are discussed.

Reproductive and other factors and risk of epithelial ovarian cancer: an Australian case-control study. Survey of Women's Health Study Group

Of the few factors known to be associated with epithelial ovarian cancer, the most consistently observed relate to women's reproductive function, although even here uncertainties remain. We have undertaken a case-control study involving personal interviews with over 1,600 women, the largest of its kind to date, to investigate further the associations between women's reproductive histories and other factors and the development of ovarian cancer. Cases were drawn from women diagnosed with epithelial ovarian cancer in 3 Australian states, Queensland, New South Wales and Victoria, between August 1990 and December 1993, and controls were drawn at random from the electoral roll, stratified by age and geographic region. Trained interviewers administered standard questionnaires to obtain detailed information about women's reproductive and contraceptive histories and other factors of interest, such as smoking and family history of ovarian or other cancer. Findings were based on data from 824 cases and 860 controls and confirmed the reduced risk of ovarian cancer associated with increasing parity and duration of use of the oral contraceptive pill (OCP), hysterectomy and tubal ligation. The strongest association of all was seen with use of the OCP for 10 years or more. An inverse association between ovarian cancer and age at first birth was observed, but this was not statistically significant. There were no associations between development of ovarian cancer and number of incomplete pregnancies, use of hormone replacement therapy or menstrual history. Among other factors considered, education after leaving school was negatively associated and high body mass index, family history of ovarian cancer, use of talc in the abdominal or perineal region and smoking were positively associated with occurrence of ovarian cancer.

Subareolar breast cancer: long-term results with conservative surgery and radiation therapy

PURPOSE

It has been suggested that patients presenting with breast cancers within 2 cm of the nipple areolar complex represent a relative contraindication to conservative management due to either a compromised cosmetic result associated with sacrifice of the nipple areolar complex, reluctance to include the entire nipple areolar complex in the conedown field, or increased risk of multicentricity. We have reviewed our experience of conservatively treated patients with specific reference to the subset of patients presenting with tumors within 2 cm of the nipple areolar complex.

METHODS AND MATERIALS

Between January 1970 and December 1989, 1014 patients with early stage breast cancer were treated at Yale-New Haven Hospital by excisional biopsy with or without axillary lymph node dissection. Of the 1014 charts reviewed, a total of 98 patients fulfilled the criteria of having a central/ subareolar breast cancer. Reexcision was performed on only 16 patients. Following conservative surgery, patients were treated with radiation therapy to the intact breast to a total median dose of 48 Gy with conedown to a total of 64 Gy. adjuvant systemic therapy and regional nodal irradiation were administered as clinically indicated.

RESULTS

As of December 1993, the median follow-up for the 98 patients in this study was 9.03 years. The majority of patients had presented with either a palpable mass or a mammographically detected lesion. Three patients presented with Paget's disease, five with nipple discharge, and seven with nipple inversion. Ten of the 98 patients had the nipple areolar complex sacrificed at the time of surgery, while the remaining 88 patients had the entire nipple areolar complex included in the conedown field. Four of these 88 patients had the nipple partially blocked during the electron conedown. There were no significant complications associated with including the entire nipple areolar complex within the conedown field to a median dose of 64 Gy. Six of the 98 patients experienced a local recurrence, three experienced a regional recurrence, and nine experienced distant metastasis. The actuarial 10-year survival (0.79 +/- 0.06), distant disease-free survival (0.88 +/- 0.04) and breast recurrence-free survival (0.84 +/- 0.07) were not significantly different from those patients who presented with cancers in other parts of the breast.

CONCLUSIONS

Patients presenting with subareolar breast cancers within 2 cm of the nipple areolar complex are suitable candidates for conservative surgery and radiation therapy. In the majority of patients in this study, the nipple areolar complex did not need to be sacrificed and could be safely included in the electron conedown field with acceptable complications and cosmesis. A subareolar breast cancer does not represent a relative contraindication to conservative management in patients with early stage breast cancer.

Holistic medicine

When the author completed medical school in 1981, the importance of psychoneuroimmunology, treating patients as a 'whole person', and experiencing meditation as a form of stress management, were not covered in the medical curriculum as they are now. This article gives a brief overview of these topics and presents several case histories and studies to illustrate the benefits of a holistic approach.

Small cell carcinoma of the cervix

Small cell carcinoma of the cervix is an uncommon aggressive variety of cervical cancer. Between 1982 and 1993, eight cases of this disease were diagnosed at the Queensland Centre for Gynaecological Cancer among 1586 cervical cancers. Treatment results have been poor with one long-term survivor. Literature review suggests that aggressive chemotherapy combined with surgery and/or radiotherapy may improve survival.

Cross-reactivity of alternate plant sources of latex in subjects with systemic IgE-mediated sensitivity to Hevea brasiliensis latex

BACKGROUND

Previous studies have suggested that there is cross-reactivity in subjects sensitive to natural rubber proteins with other plant proteins such as banana, chestnut, and avocado. There are numerous other plants known to produce rubber including Parthenium argentatum and Ficus elastica. It is not known whether patients with IgE-mediated systemic reactions caused by the common source of natural rubber Hevea brasiliensis are also sensitive to the rubber-containing material from these other plant sources of latex. It is also not certain how much the allergenicity of latex made from Hevea brasiliensis can be reduced by extracting proteins from the sap since some proteins are tightly associated with the cis-1,4-polyisoprene.

OBJECTIVE

In this study we investigated whether there would be cross-reactivity to other natural sources of latex in these patients.

METHODS

Seven patients with histories of systemic type I hypersensitivity to latex products had strongly positive skin tests to Hevea brasiliensis latex from two different sources. These subjects were tested by the prick method for sensitivity to three other natural sources of latex. These included latex-containing material from Parthenium-argentatum and Ficus elastica as well as washed and centrifuged rubber particles from Hevea brasiliensis sap.

RESULTS

All subjects had negative skin tests to all dilutions of the rubber samples from these other natural sources of latex.

CONCLUSION

These results suggest several potential sources of natural hypoallergenic latex that might be tolerated by latex-sensitive individuals.

Laryngopharyngoesophagectomy for advanced hypopharyngeal and esophageal squamous cell carcinoma: the Yale experience

The 5-year survival rate for patients with hypopharyngeal squamous cell carcinoma invading the upper esophagus is below 25% regardless of therapy. Most patients with advanced disease--unable to eat or breathe--die within 18 months of diagnosis. Because these patients, on average, have a limited time to live, surgical treatment should aim to maximize the quality of remaining life. Essential to this goal are complete tumor removal and rapid return to oral feeding. Furthermore, short hospital stay and low perioperative morbidity are especially important in these patients. We performed total laryngopharyngoesophagectomy (LPE) with gastric transposition in 34 patients with hypopharyngeal and cervical esophageal squamous cell carcinoma. There has been one perioperative death (3%) and 1 temporary fistula (3%). No major mediastinal or intrathoracic complication occurred. On average, patients began oral feeding by postoperative day 10, with return to a full diet and discharge home within 16 days, maximizing both quality and quantity of time remaining outside the hospital.

Genetic susceptibility to colorectal cancer in patients under 45 years of age

A study was conducted to assess the genetic contribution to the development of colorectal cancer in young probands. Of 83 patients aged 45 years or under diagnosed with colorectal cancer in one health region over a 2-year period, 65 or their surviving next of kin were available for interview, from whom were obtained 60 detailed and five limited family histories. Five families fulfilled the Amsterdam criteria and a further eight satisfied less strict criteria for hereditary non-polyposis colorectal cancer, a total of 20 per cent of the cohort. Eleven of these families came from the subgroup of 13 probands who had one or more first-degree relatives with colorectal cancer. Overall the relative risk of colorectal cancer in close relatives was 5.2 (P < 0.0001). This risk was highest for female relatives at 9.7 (P < 0.0001) and relatives of female probands at 6.7 (P < 0.0001). This study highlights the importance of taking a family history in this group of patients. Screening by colonoscopy for all close relatives of young patients with colorectal cancer is recommended.

Homozygous deletions on the short arm of chromosome 9 in ovarian adenocarcinoma cell lines and loss of heterozygosity in sporadic tumors

Rat ovarian surface epithelial cells transformed spontaneously in vitro have been found to have homozygous deletions of the interferon alpha (IFNA) gene. This suggests that inactivation of a tumor-suppressor gene in this region may be crucial for the development of ovarian cancer. We therefore used microsatellite markers and Southern analysis to examine the homologous region in humans--the short arm of chromosome 9--for deletions in sporadic ovarian adenocarcinomas and ovarian tumor cell lines. Loss of heterozygosity occurred in 34 (37%) of 91 informative sporadic tumors, including some benign, low-malignant-potential and early-stage tumors, suggesting that it is an early event in the development of ovarian adenocarcinoma. Furthermore, homozygous deletions on 9p were found in 2 of 10 independent cell lines. Deletion mapping of the tumors and lines indicates that the candidate suppressor gene inactivated as a consequence lies between D9S171 and the IFNA locus, a region that is also deleted in several other tumors and that contains the melanoma predisposition gene, MLM.

An increase in Haemophilus influenzae type B vaccination among preschool-aged children in inner-city Los Angeles, 1990 through 1992

Haemophilus influenzae type b (Hib) vaccination coverage and disease incidence were measured among preschool-aged children residing in inner-city Los Angeles. Among children 1.5 to 14 months of age, vaccination coverage of at least one dose increased from 0% in 1990 to 82% (95% confidence interval [CI] = 73%, 91%) in 1992. Among children 15 to 59 months old, vaccination coverage of at least one Hib dose administered at or after age 15 months increased from 35% (95% CI = 29%, 41%) in 1990 to 63% (95% CI = 56%, 70%) in 1992. Although Hib vaccination has reduced disease incidence in this population, greater use of vaccine can result in further reductions.

Response to desipramine treatment in adolescent depression: a fixed-dose, placebo-controlled trial

OBJECTIVE

To determine the efficacy and tolerability of the tricyclic antidepressant desipramine (DMI) in the treatment of DSM-III-R-diagnosed major depressive disorder in adolescents.

METHOD

Sixty adolescents (42 female, 18 male; aged 15 to 19 years) diagnosed with major depressive disorder using clinical interview and Schedule for Affective Disorders and Schizophrenia for School-Age Children were randomized to receive either DMI (200 mg daily in divided doses) or placebo for six consecutive weeks following a 1-week placebo period. Treatment outcome was determined using the Hamilton Depression Rating Scale and the Beck Depression Inventory. Tolerability was determined using a symptom side effects scale. In addition, a variety of laboratory and cardiovascular monitoring was performed.

RESULTS

No significant differences in treatment outcome between DMI- and placebo-treated groups were determined. Neither DMI, nor its metabolite 2-hydroxy-DMI, nor their ratio, was positively correlated to treatment outcome. The DMI group endorsed more side effects but there were no significant between-group differences in any laboratory, electrocardiographic, or other cardiovascular parameters apart from heart rate, which was increased in the DMI-treated group (p = .03).

CONCLUSIONS

Given the findings of this study and our review of previously published reports of tricyclic antidepressant treatment in this population, the routine use of short-term (6 weeks) DMI in the treatment of adolescent depression is not supported by the data on hand. Further investigations into what constitutes optimal psychopharmacological treatment of adolescent depression are warranted.

Modified technique for efficient detection of microsporidia

Changes in temperature (from room temperature to 50 degrees C) and staining time (from 90 to 10 min) were evaluated as a means of improving the detection of microsporidia from stool specimens. A blinded and independent comparison of 50 known positive matched-specimen pairs by three technologists resulted in consistently easier microscopic detection. The background is clearer, and spores stain more intensely. Staining time is reduced by 80 min.

Protection provided by Haemophilus influenzae type b conjugate vaccines in Los Angeles County: a case-control study

The objective was to assess the degree of disease control and to evaluate the protective efficacy of licensed Haemophilus influenzae type b (Hib) conjugate vaccines (HbOC, PRP-OMP, PRP-D) used routinely in children 2 to 35 months of age. We conducted a case-control study in Los Angeles County between January 1, 1991, and December 31, 1992, and a cohort analysis of Hib cases between 1983 and 1992. For the case-control study 105 cases of invasive Hib disease were identified and 767 geographically and age-matched controls were selected by random digit telephone dialing. Sixteen HbOC vaccine failures occurred > 14 days after a single dose of vaccine, 6 vaccine failures after 2 doses and 3 failures after 3 doses; 2 cases occurred 6 and 12 days, respectively, after an initial dose of HbOC. The protective efficacy of a single HbOC vaccine dose was 71.1% (95% confidence interval (CI), 37.5 to 87.2%). After 2 doses the efficacy was 88.8% (95% CI, 59.5 to 96.9%) and after 3 doses it was 94.4% (95% CI, 68.0% to 99.0%). Similar 95% CIs were seen for 1 and 2 doses of PRP-OMP vaccine. Adjustment of efficacy estimates for potential confounding variables did not significantly alter the results. Despite relatively low rates of immunization (20 to 60%) the rates of Hib disease decreased strikingly between 1990 and 1992 (from 24.2 to 4.4/100,000 children < 5 years of age). The HbOC conjugate vaccine, used predominantly but incompletely during this period, provided substantial protection against invasive Hib disease in children immunized between 2 and 35 months of age.(ABSTRACT TRUNCATED AT 250 WORDS)

Flicker sensitivity and fundus appearance in pre-exudative age-related maculopathy

PURPOSE

To evaluate whether foveal flicker sensitivity and fundus appearance are good predictors of exudative age-related maculopathy (ARM) when the effects of aging, retinal illuminance, and criterion differences are controlled.

METHODS

Fellow eyes of monocular exudative ARM patients were tested at baseline. Seven of these eyes have now developed exudative ARM. Therefore, at baseline they were in pre-exudative stages of ARM. The foveal flicker sensitivity and fundus appearance of the pre-exudative and nonconverted eyes were compared with healthy, age-matched eyes. The flicker stimulus was a uniform, 2.8 deg circular field at 660 nm, modulated sinusoidally at frequencies from 2.5 to 50 Hz. Fundus photographs were evaluated using the Wisconsin ARM grading system.

RESULTS

Flicker modulation sensitivity at two frequencies discriminated pre-exudative from healthy older eyes with 100% accuracy. Using the same criterion, pre-exudative eyes also were discriminated from nonconverted eyes with 100% accuracy. Whereas an overall fundus ARM risk score discriminated pre-exudative from healthy older eyes with 100% accuracy, it did not discriminate pre-exudative from nonconverted eyes at better than chance levels.

CONCLUSIONS

There were functional changes in the retina preceding development of exudative ARM. Foveal flicker sensitivity at low- to mid-temporal frequencies seemed highly sensitive to these pre-exudative changes in this relatively small group of subjects. The authors hypothesize that foveal flicker sensitivity is a good predictor of exudative ARM and a sensitive monitor of retinal function in pre-exudative ARM. These predictions are being tested on a larger, independent sample.

Central splanchnic venous thrombosis. Often unsuspected, usually uncomplicated

Despite the increasingly frequent noninvasive detection of central splanchnic venous thrombosis (CSVT), its pathophysiology and clinical significance remain incompletely understood. We reviewed 50 consecutive cases of partially or totally occlusive thrombosis, primarily of the portal (60%) and splenic (40%) veins. Thirty-eight percent of patients had cancer; 26% had portal hypertension or other conditions associated with splanchnic venous stasis; and in 20%, thrombosis developed postoperatively. Angiography (89%), duplex ultrasonography (46%), CT scan (32%), and MRI (16%) were all useful diagnostic modalities. In 58% of cases, CSVT was clinically unsuspected, and 32% of patients were essentially asymptomatic. Variceal hemorrhage occurred in 30% of cases, and abdominal pain was notable in 26%. Whereas 50% of patients died < or = 6 months of diagnosis, only one of these deaths was directly attributable to CSVT; the remainder were secondary to underlying disease unrelated to the CSVT itself. CSVT, increasingly detected but often unsuspected clinically, is characterized by a self-limited and nonlethal course in the majority of patients. Death from associated disease is, however, common. The treatment and prognosis of CSVT should therefore be dictated by its clinical manifestations and the setting in which it occurs, rather than by the venous thrombosis itself.

Mobile telephones interfere with medical electrical equipment

Electromagnetic interference in medical electrical equipment has not been a serious problem in recent years even with the proliferation of analogue mobile phones and two-way handheld radios. With the introduction of GSM digital mobile phones into Australia we have conducted measurements and found that, within 2m, the electric fields from digital mobile phones can exceed the immunity level of 7 V/m recommended by the US Food and Drug Administration (FDA) for medical electrical equipment. Current analogue mobile phones were shown to produce electric fields that exceed the 7 V/m level only at relatively shorter distances. In another test, both analogue and digital mobile phones were operated close to a range of typical medical electrical equipment. It was found that existing equipment generally meets the FDA standard, but digital mobile phones caused a variety of artefacts and alarm conditions. This problem must be addressed by the medical engineering profession; in the meantime, nursing and other staff should be educated to recognise these problems and restrictions must be placed upon the use of mobile phones in hospitals.

Immunologic parameters 2 years after high-titer measles immunization in Peruvian children

Immunization with high-titer measles vaccines has been associated with excess mortality in children 2-4 years after vaccination. In this study, immunologic parameters in 64 Peruvian children who had been immunized an average of 27 months earlier with high-titer vaccines were compared with parameters in 76 recipients of low-titer vaccines. Delayed-type hypersensitivity, lymphocyte phenotype distributions by flow cytometry, and lymphoproliferation after phytohemagglutinin (PHA) stimulation were assessed. High-titer recipients had smaller indurations to tetanus, diphtheria, and Proteus (P < .05) antigens, decreased PHA stimulation (P = .04), and a lower percentage of CD4+ lymphocytes (P = .04) than low-titer recipients. After adjustment for sex, concurrent illnesses, and other variables in regression analyses, high-titer recipients had a lower percentage of CD4+ lymphocytes (P = .025) and decreased lymphocyte proliferation to PHA (P = .058). These results may provide a clue to the pathogenesis of delayed excess mortality after high-titer measles vaccination in some developing countries.

The Development of Alcohol Strategies in England and Wales

Alcohol has become a major public health problem in the UK. In order to coordinate the work of both statutory and non-statutory agencies more efficiently and effectively, a government circular HN(89)4 has emphasized the need for development of local multi-agency alcohol misuse prevention strategies. Despite expressed enthusiasm for alcohol strategies, information about their development, effectiveness and overall national progress is scarce and needs to be improved.

This national survey reports the most recent and accurate information about the development of district and regional alcohol strategies in England and Wales. Although only 51 (27%) districts stated they had a strategy, it was encouraging to find 90 (47%) other districts that were in the process of, or planning to develop such a document.

Of the 51 districts with a strategy, the following key findings were noted:

Forty-three (84%) districts stated that they had started to implement their strategy, but none claimed to have fully implemented it. Thirty-six (71%) districts stated that their strategy had an action plan. Thirty-four (67%) districts stated that their strategy had been officially endorsed by the district health authority. Thirty-eight (76%) districts stated that they had identified an individual or group to monitor the strategies' implementation.

The results of the survey could be of interest to the Department of Health, the Faculty of Public Health Medicine, the Health Education Authority and the regional alcohol coordinators. The development of district and regional alcohol strategies has a role to play in achieving the alcohol targets in the recent Health of the Nation White Paper and is also a good example of the formation of healthy alliances to tackle a major public health problem.

Transmission of human papillomaviruses from mother to child

Exfoliated cervical epithelial cells from women 6 weeks postpartum were analyzed for human papillomavirus (HPV) DNA using the polymerase chain reaction, and results were compared with those from buccal mucosal smears from their babies. Eleven mothers had genital genotypes of HPV in their cervical smears, and the children of 8 of these had HPV of the same genotype in buccal mucosal cell samples. Nineteen mothers had no HPV DNA detected in their cervical smears, and 1 of the buccal mucosal cell samples from their children was positive for HPV DNA (p < 0.0001). Contamination of a child's mouth with 'genital' HPV from a mother's cervix appears to occur commonly at birth or in the perinatal period, and to persist for at least 6 weeks. This observation has implications for the epidemiology and management of HPV associated cancer and precancerous conditions in the cervix and the mouth.

Mid-frequency loss of foveal flicker sensitivity in early stages of age-related maculopathy

Temporal contrast sensitivity in eyes at risk for exudative age-related maculopathy (ARM) was compared to that in age-matched healthy older eyes. The test stimulus was a foveally viewed, flickering, long-wavelength 2.8 degrees diameter circle in an equiluminant (photopic) surround. Retinal illuminance and decision criterion differences were experimentally controlled. Eyes in the healthy and ARM-risk groups had 20/30 or better Snellen acuity and intraocular pressure of less than 22 mmHg. Nevertheless, the ARM-risk patients were less sensitive to flicker contrast, especially for mid-temporal frequencies. This suggests that flicker sensitivity may be useful in identifying patients at risk for exudative ARM. In addition, comparison with other research reveals a paradox: Mid-temporal frequency sensitivity losses may be attributable primarily to a "high temporal frequency" mechanism.

Foveal flicker sensitivity discriminates ARM-risk from healthy eyes

The "good" eyes of 13 patients with monocular exudative ARM were compared with age-matched healthy eyes of 19 subjects. Membership in the two study groups was based upon careful clinical evaluation of the tested eye as well as upon status of the fellow eye. We asked whether temporal contrast sensitivity for a long-wavelength, low spatial frequency stimulus can be used to identify the group in which a given eye belongs. Using step-wise discriminant analysis, we found that the ARM-risk and healthy eyes could be classified with 78% accuracy on the basis of foveal flicker sensitivity at two temporal frequencies--14 and 10 Hz (in order of estimated weight.)

Preliminary evaluation of flicker sensitivity as a predictive test for exudative age-related maculopathy

Flicker contrast sensitivity was tested in the "good" eyes of 13 patients with monocular exudative age-related maculopathy (ARM). The stimulus was a foveal, long-wavelength, low spatial frequency 2.8 degrees circle in an equiluminant (photopic) surround. Two of these ARM-risk eyes have since developed exudative ARM. Compared to healthy age-matched eyes, the two eyes that developed exudative ARM had significantly lower sensitivity at 10-40 Hz up to 9 mo before exudative symptoms appeared. The implications of these results regarding the time-course of ARM and the predictive value of foveal contrast sensitivity testing are considered. Based upon data and theoretical considerations, the authors speculate that sensitivity loss between 10 and 40 Hz is a good predictor of which eyes will develop exudative ARM. This proposal will be tested by new data from current as well as new ARM-risk subjects.

Site-specific binding constants for actinomycin D on DNA determined from footprinting studies

We report site-specific binding constants for the intercalating anticancer drug actinomycin D (Act-D), binding to a 139-base-pair restriction fragment from pBR 322 DNA. The binding constants are derived from analysis of footprinting experiments, in which the radiolabeled 139-mer is cleaved using DNase I, the cleavage products undergo gel electrophoresis, and, from the gel autoradiogram, spot intensities, proportional to amounts of cleaved fragments, are measured. A bound drug prevents DNase I from cleaving at approximately 7 bonds, leading to decreased amounts of corresponding fragments. With the radiolabel on the 3' end of the noncoding strand (A-label), we measured relative amounts of 54 cleavage products at 25 Act-D concentrations. For cleavage of the 139-mer with the label on the 3' end of the coding strand (G-label), relative amounts of 43 cleavage products at 11 Act-D concentrations were measured. These measurements give information about approximately 120 base pairs of the restriction fragment (approximately 12 turns of the DNA helix); in this region, 14 strong and weak Act-D binding sites were identified. The model used to interpret the footprinting plots is derived in detail. Binding constants for 14 sites on the fragment are obtained simultaneously. It is important to take into account the effect of drug binding at its various sites on the local concentration of probe elsewhere. It is also necessary to include in the model weak as well as strong Act-D sites on the carrier DNA which is present, since the carrier DNA controls the free-drug concentration. As expected, the strongest sites are those with the sequence (all sequences are 5'----3') GC, with TGCT having the highest binding constant, 6.4 x 10(6) M-1. Sites having the sequence GC preceded by G are weak binding sites, having binding constants approximately 1 order of magnitude lower than those of the strong sites. Also, the non-GC-containing sequences CCG and CCC bind Act-D with a binding constant comparable to those of the weak GGC sites. The analysis may reveal drug-induced structural changes on the DNA, which are discussed in terms of the mechanism of Act-D binding.