Attitudes and Concerns of Pre-Pubescent and Pubescent Girls about Breast Health and Breast Cancer: An Unmet Need

Background: Prior research has indicated that girls have unaddressed fears about breast health and breast cancer. In a Breastcancer.org online survey (SABCS 2008 Abstract#5078), 26% of girls have already worried they may have breast cancer and 73% reported that a relative or close acquaintance had already been diagnosed. Their fears are magnified by the current trend of early onset of breast development and their sensitivity to high media coverage of breast cancer. We hypothesize that girls have limited opportunities and are without the emotional capacity and communication skills necessary to gather and process this information at home, in school, and in the doctor's office.Methods: Breastcancer.org, the Taking Care of Your “Girls” book project, and the Lankenau Hospital Health Education Center conducted an online survey of girls in middle and high schools prior to the delivery of its in-school Basic Breast Health Assembly Program in 13 Philadelphia, Atlanta, Washington, and Los Angeles area schools. 4246 girls attended an assembly, of which 3397 participated in the student survey. 1067 adult female family members (AFFM)—mostly mothers—completed the family member survey.Results: In total, 33% of girls had already learned about breast health and breast cancer in school. 48% of girls wanted to attend the Assembly Program; 93% of AFFMs wanted their girls to participate in the Assembly Program. 50% of girls said they felt uneasy starting the conversation about these topics with their AFFM, 97% of AFFMs said they felt comfortable starting the conversation with their girls, but only 43% of the girls report having the conversation. Of the girls who talked to a parent, 91% talked to their mothers and only 1% talked with their fathers. Girls and AFFMs offered many tips on how to start and sustain a healthy dialogue on these topics: listen, be open, make it fun, pick a private place and time, share experiences, provide facts, and call in experts when you need more information.42%, 18%, and 23% of girls, respectively, have talked to a doctor, sister, or friend about these topics. 50% of girls want to learn breast self-exams from their doctors.Discussion: This survey indicates that girls have unmet informational needs on breast health and breast cancer. This was a source of anxiety for both girls and their AFFMs. There was a willingness to engage in educational activities by both girls and AFFMs, but the dialogue opportunities and communication skills were seen as lacking. Girls identified AFFMs, schools, and doctors as their preferred sources of this information.Girls' ability to express their anxiety, replace fears with facts, learn breast healthy behaviors, and deal with a loved ones' diagnosis requires education, modeling, and an ongoing dialogue. This survey provides guidance for educators and healthcare professionals regarding research into interventions seeking to correct this previously underappreciated gap in public health education.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 1037.

Therapie extremer Tumorschmerzen mit Morphin und (S)-Ketamin

We are reporting on the case of an 11-year old girl with a malignant tumour. The extreme pain throughout the body could not be treated by conventional methods. By intravenous application of a morphine and s-ketamine mixture we were able to achieve a very effective analgesic result. Apart from the opiate effect of the morphine the decisive factor was the NMDA-antagonism of the s-ketamine. The latter suppresses central sensitisation and chronic pain and reduces or even prevents the development of opioid tolerance. It was possible to use smaller opiate doses more effectively, thus reducing the side effects of the pain therapy. Under associated whole-body thermochemotherapy the girl experienced general pain relief and we were able to return to conventional therapy with a fentanyl plaster.

Gross-total surgery of supratentorial low-grade gliomas under intraoperative MR guidance

BACKGROUND AND PURPOSE

Length of survival of patients with low-grade glioma correlates with the extent of tumor resection. These tumors, however, are difficult to distinguish intraoperatively from normal brain tissue, often leading to incomplete resection. Our goal was to evaluate the effectiveness of intraoperative MR guidance in achieving gross-total resection.

METHODS

We studied 12 patients with low-grade glioma who underwent surgery within a vertically open 0.5-T MR system. During surgery, localization of residual tumor tissue was guided by interactive, near real-time imaging. The amount of residual tumor tissue on MR images was evaluated at the point of the operation at which the neurosurgeon would have terminated the procedure under conventional conditions (first control) and again before closing the craniotomy.

RESULTS

Significant residual tumor (more than 10% of original tumor volume) was shown in eight patients at the first control condition. The percentage of resection varied from 26% to 100% (mean, 68%) at this time. Twelve tissue samples from seven patients were obtained in areas identified as residual tumor on MR images. In 10 cases, the neuropathologic investigation confirmed the presence of residual low-grade glioma; in two cases, the borderzone of tumor was identified. In evaluating the final sets of images, we found total resection in six cases, over 90% resection in five cases, and 85% resection in one case (mean, 96%).

CONCLUSION

Surgical treatment of low-grade gliomas under intraoperative MR guidance provides improved resection results with maximal patient safety.

Paclitaxel-induced stomal neuropathy: a unique cause of pain in a patient with ileal conduit

We present a case of unusual chemotherapy-induced neurotoxicity in a patient who had undergone radical cystoprostatectomy and ileal conduit diversion for invasive bladder cancer. On routine computed tomography scan several years later, he was diagnosed with metastatic transitional cell carcinoma involving the retroperitoneal lymph nodes. The patient received systemic chemotherapy, including a combination of paclitaxel (Taxol) and gemcitabine (Gemzar). During this treatment, the patient developed spasmodic pain and dysesthesia in the stoma area, with no apparent skin irritation or any other local finding. These symptoms resolved about 3 months after completion of the therapy.

Transurethral resection and partial cystectomy for invasive bladder cancer

Bladder-preserving modalities for patients with invasive bladder cancer have become increasingly popular in recent years. Surgical-only approaches, such as transurethral resection (TUR) or partial cystectomy, are unique among a variety of bladder-preserving modalities, most of which involve combination with radiation and chemotherapy. TUR and partial cystectomy remain incompletely evaluated due to relatively small series in the literature and the lack of standardized selection criteria. The outcome as measured by long-term bladder preservation and overall survival is not dissimilar to concurrent radical cystectomy series, possibly because of positive selection of patients.

Complete androgen blockade for prostate cancer: what went wrong?

PURPOSE

We summarized and critically assessed all available data from phase III clinical trials on complete androgen blockade versus surgical or medical castration alone.

MATERIALS AND METHODS

Published results in journals and abstracts of phase III trials, and published meta-analyses were reviewed. We also reviewed quality of life and toxicity issues associated with the addition of antiandrogens to medical or surgical castration. Finally, we discuss the original rationale for complete androgen blockade in the context of current knowledge.

RESULTS

A total of 27 clinical trials using various combinations of androgen deprivation were identified, of which 3 showed a statistically significant benefit for the complete androgen blockade arm. There were 5 publications of meta-analyses that each used different selection criteria for the inclusion of studies in the final analysis. Toxicity and quality of life have not been widely investigated in prospective fashion but the available data suggest a higher toxicity rate and decreased quality of life with complete androgen blockade.

CONCLUSIONS

The extensive body of data does not support routine use of antiandrogens in combination with medical or surgical castration as first line hormonal therapy in patients with metastatic prostate cancer.

Medical management of HIV disease in children

Significant advances have been made in the understanding of the pathophysiology of HIV infection since the beginning of the epidemic. This knowledge has translated into the development of new therapies for HIV and opportunistic infections, laboratory advances in monitoring viral and immune status, and a better understanding of factors affecting patient outcome. Concomitantly, significant progress has been made in the medical management of children with HIV infection in the past 5 years. The number of children reported with AIDS in the United States is decreasing, and efforts are shifting from caring for children with advanced immunosuppression and severe opportunistic infections to early HAART, maintenance of the immune system, and prevention of opportunistic infections. Primary care physicians are now more involved and informed in the care of HIV-infected patients. Although published data are limited, physicians who have been working with this population have observed a dramatic improvement in the quality of life and length of survival of these patients. Unfortunately, this progress is not shared by developing countries where resources are minimal and antiretroviral agents are commonly unavailable. Although efforts to develop a vaccine to prevent HIV infection are ongoing, progress has been slow. Education and awareness continue to be the most powerful weapons against HIV.

Preliminary evaluation of a short course of estramustine phosphate and docetaxel (Taxotere) in the treatment of hormone-refractory prostate cancer

Preclinical data suggest that small quantities of estramustine phosphate are synergistic with taxanes and may be useful in the treatment of hormone-refractory prostate cancer. The current trial was designed to reduce the duration of exposure to estramustine phosphate, which carries with it the risk of anorexia and gastrointestinal, cardiovascular, and thromboembolic toxicity during long-term treatment. Patients with histologically confirmed adenocarcinoma of the prostate showing evidence of progressing disease 4 to 6 weeks after antiandrogen withdrawal were enrolled into the study. Patients may have received up to two prior chemotherapy regimens. Patients received estramustine phosphate 280 mg orally every 6 hours for a total of five doses (24-hour exposure), docetaxel (Taxotere; Rhône-Poulenc Rorer, Collegeville, PA) 70 mg/m2 intravenously over 1 hour, coumadin 2 mg orally every day, and dexamethasone as premedication for docetaxel. Cycles were repeated every 21 days, up to a maximum of 6. Of the 18 evaluable patients, seven showed more than 50% declines in prostate-specific antigen for a duration > or =4 weeks; two of eight patients had soft tissue partial responses. Nine of 11 had improvement in pain and/or urinary symptoms. In a total of 98 cycles, grade 3 toxicities observed included leukopenia (N = 7), neutropenia (N = 6), fatigue (N = 13), headache (N = 1), local skin reactions after extravasation (N = 2), nail changes (N = 1), diarrhea (N = 2), and hyperglycemia (N = 3); grade 4 toxicities included neutropenia/fever requiring admission (N = 2), leukopenia (N = 2), and neutropenia (N = 6). No thromboembolic complications were seen. All toxicities were reversible within 1 week after occurrence. Thus, preliminary evidence suggests that in this heavily pretreated patient population 1-day treatment with an estramustine/docetaxel combination is active and has acceptable toxicity.

Rapid disease progression after the administration of bicalutamide in patients with metastatic prostate cancer

We report 5 patients with advanced metastatic prostate cancer who took bicalutamide 50 mg/day for "second-line" hormonal manipulation and demonstrated a rapid rise in prostate-specific antigen (PSA) shortly after the initiation of bicalutamide. After discontinuation of the drug, PSA levels declined in 4 patients and stabilized in the fifth. In 2 of the patients, the PSA rise was associated with an increase in pain level, which subsided after the treatment was stopped. The timing of the rapid changes in PSA and pain levels suggests a direct effect of bicalutamide. The most probable explanation for this observation is a very early agonist activation of androgen receptor by bicalutamide, similar to the underlying mechanism of the "antiandrogen withdrawal syndrome."

Elevated urinary fibronectin levels after transurethral resection of bladder tumour: a possible role in patients failing therapy with bacillus Calmette-Guérin

OBJECTIVE

To investigate fibronectin levels in urine samples from patients with noninvasive transitional cell carcinoma (TCC) of the bladder immediately and for 4 weeks after transurethral resection of bladder tumour (TURBT), to determine whether soluble fibronectin within the bladder, which blocks the attachment of bacillus Calmette-Guérin (BCG), might lower the efficacy of BCG therapy over this period.

PATIENTS AND METHODS

Urinary fibronectin was measured using an enzyme-linked immunosorbent assay in 25 patients with superficial bladder TCC who underwent TURBT for complete resection. Eight samples were collected for each patient, one before and seven during the 4 weeks after TURBT.

RESULTS

High levels of urinary fibronectin were detected in 18 patients (72%) after TURBT. In 16 patients the fibronectin level returned to normal within 2 weeks of surgery. The other two patients showed elevated levels of fibronectin for > 4 weeks.

CONCLUSIONS

These results show that urinary fibronectin concentration is significantly increased in most patients after TURBT and this should be considered in patients who receive BCG therapy. Treatment within the first 2 weeks after TURBT may be associated with a high failure rate, as urinary fibronectin levels were increased significantly in about three-quarters of these patients during that period. Indeed, the persistent elevation of fibronectin, occurring in two of the present patients, may be responsible for some of the failures of BCG therapy when it is administered 2-5 weeks after surgery.

[MR-track pointer. A reusable device for localization during interventions]

PURPOSE

Development of an helpful instrument for a better planning and orientation during MR guided interventions.

MATERIAL AND METHODS

We developed a reusable, sterilizable instrument that can be filled both with a solution of Gd-DTPA (1%) and with a sodium chloride solution (0.9%). The pointer has a diameter of 3 and 5 mm resp. and its length is 100-150 mm. The instrument can be combined with an interactive stereotactic tracking device.

RESULTS

The MR-Track-Pointer can be fixed to the two handpieces of the integrated interactive tracking system without problems. The pointer can be seen both on T1w and T2w sequences inside and outside of the tissue. This new instrument can be interactively used for reliable planning the biopsy trajectory, planning craniotomies and identifying structures which are only visible on MR images.

CONCLUSIONS

The MR-Track-Pointer is an ideal supplement for the integrated virtual tracking system. It permits a minimal invasive orientation and facilitates the exact localisation of suspect lesions in sensible regions during MR guided interventions, e.g. diagnostic biopsies and tumour resections.

Melatonin receptors in PC3 human prostate tumor cells

Melatonin, secreted nocturnally by the pineal gland, can bind to human benign prostate epithelial cells and attenuate their growth and viability. In the present study, melatonin binding and responses were explored in the human steroid-independent PC3 prostatic tumor cells. PC3 cells bound 125I-melatonin with low affinity (Kd ca. 0.9 nM) at high as well as low cell density. Melatonin enhanced cGMP and 3H-thymidine incorporation at low, but attenuated them at high cell density. In addition, melatonin inhibited cAMP at low, but augmented it at high cell density. These effects were associated with an increase in cell count at low- but not high-density cultures. Pertussis toxin treatment suppressed 125I-melatonin binding and ablated all the effects of melatonin on 3H-thymidine incorporation, cAMP, and cGMP at both cell densities. Cholera toxin treatment failed to block the effects of melatonin on 3H-thymidine incorporation, but prevented the modulation by melatonin of cAMP at low and cGMP at high cell density. The cGMP analog 8-Br-cGMP, inhibited melatonin's effects on 3H-thymidine incorporation at both cell densities. H89, a protein kinase A inhibitor, prevented melatonin's effects on 3H-thymidine incorporation at low but not high cell density. These results provide the first demonstration of direct interaction of melatonin with hormone-insensitive prostate tumor cells. The melatonin receptors in the PC3 cells are coupled to pertussis toxin-sensitive G proteins to induce cell density-dependent changes in cGMP, cAMP, and cell growth.

Noninvasive detection of bladder cancer with the BTA stat test

PURPOSE

We assess the sensitivity and specificity of the noninvasive BTA stat urine test for detection of primary and recurrent bladder cancer with special reference to the size, grade and stage of the tumors, and examine the effect of intravesical bacillus Calmette-Guerin treatment on the results.

MATERIALS AND METHODS

A total of 250 patients recruited from 3 medical centers provided voided urine samples for the BTA stat test and cytopathological study. Of these patients 162 were monitored following resection of bladder tumors and 88 were evaluated for the first time for hematuria or irritative voiding symptoms. Each patient underwent cystoscopy. Biopsies were obtained when a bladder tumor was seen or if carcinoma in situ was suspected. The sensitivity, specificity and accuracy of the BTA stat test were compared to standard voided urine cytology.

RESULTS

No tumor was found in 122 patients, primary transitional cell carcinoma was found in 71 and cystoscopy revealed recurrent tumors in 57. Overall sensitivity of the BTA stat test was 82.8% and specificity was 68.9%. Sensitivity of urine cytology was 39.8% and specificity was 95.1%. The BTA stat test detected 90.1% of the primary and 73.7% of the recurrent tumors. All patients with carcinoma in situ, high grade tumors, muscle invasive cancer and tumors larger than 2 cm. were diagnosed by the BTA stat test.

CONCLUSIONS

The BTA stat test can be used as a screening test for bladder cancer in patients with hematuria or irritative voiding symptoms and for surveillance of those who have not been treated with intravesical bacillus Calmette-Guerin.

Erectile dysfunction following Nd-YAG visual laser-assisted prostatectomy (VLAP)

We investigated if side fire Nd-YAG visual laser prostatectomy (VLAP) causes erectile dysfunction (ED) in patients who were sexually active prior to the procedure. The 36 study patients gave a detailed medical/sexual history: physical examination included bulbo-cavernous reflex (BCR) on rectal examination and routine blood tests. Lasing time, power of the applied laser beam (in watts), coagulation site and energy intensity were recorded. Patients with new onset ED during the one year study period underwent pudendal nerve conduction (PNC), color duplex Doppler ultrasonography, and NPT/RigiScan testing. In 6 out of 36 (16.7%) patients reporting significant post-operative ED, there was a tendency towards higher energy applied and longer lasing time but no correlation between prostate size or the site of energy application. Patients reported loss of night and/or morning erections (n = 5), retrograde ejaculations (n = 2), loss of ejaculate (n = 2), and decreased sensation of orgasm (n = 3). Three had abnormal PNC, duplex Doppler showed abnormal blood supply in four, and all six had abnormal NPT/RigiScan. We believe this is the first demonstration that VLAP may be associated with a high rate of ED and that the lasing time and intensity of applied laser energy may play a role in this outcome.

Origins of horizontal cell spectral responses in the retina of marine teleosts (Centropomus and Mugil sp)

Intracellular recording and marking of horizontal cells (HCs) were carried out in isolated retinas of marine teleosts (Centropomus and Mugil sp.) to identify the cellular origins of different spectral types of S-potential. The spectral responses recorded under mesopic conditions were classified into four types: photopic L, biphasic C(R/G), biphasic C(G/R), and scotopic L(sL). Intracellular marking with Lucifer yellow (LY) or Procion yellow (PY) revealed that in the Centropomus retina an L-type response was recorded from H1 and H2 cells, C(R/G)-type from H3 cells, and sL-type from H4 cells. However, in 20% of microelectrode penetrations from the photoreceptor surface, the sequential order of response appearances was found to be L-, sL-, and C(R/G)-types. In this species, thick dendritic processes of H3 and H4 cells are distributed at the same level as the cell body. In the Mugil retina, on the other hand, L-type response was recorded from H1 cells, C(G/R)-type from H2 cells, C(R/G)-type from H3 cells, and sL-type from H4 cells, this sequential arrangement being very regular. In both species, the cone-connected H1 cells are small and possess an axon, while the two other cone HCs as well as rod-connected H4 cells are axonless. Earlier (Negishi et al., 1988) and present findings indicate that there is a wide variety of HC morphology and functional organization in the teleost retina.

Clinical characteristics and treatment of patients with oral lichen planus in Israel

Oral lichen planus (OLP) has a multiple-site involvement, with the buccal mucosa being the most prevalent. A possible relationship between OLP and the risk of malignancies in the involved site is documented. The characteristics of OLP have been studied in different populations; however, no similar studies have been conducted in any Jewish population. The purpose of this study was to evaluate the natural history of OLP in Israeli Jewish patients. Data were collected from 157 charts of patients with histologically confirmed OLP. No evidence suggesting a connection between OLP and diabetes, cardiovascular disease, smoking, alcohol use, or positive Candida culture was found. Skin involvement of lichen planus was found in one fifth of the patients. Symptomatic OLP was noted in half of the patients, mainly in those with the erosive form. In 65% of the patients with symptoms, improvement by more than 50% was shown within 2 weeks of steroid use. The transformation rate of 1.3% of OLP into malignancy was observed in the entire group. A constant follow-up for contributing symptoms and for early diagnosis of suspected transformed lesions is of utmost importance.

Anti-topoisomerase-I and clinical findings in systemic sclerosis (scleroderma)

The relationship between anti-topoisomerase-I antibodies and clinical findings was studied in 191 patients with definite systemic sclerosis. This was done by performing ELISA to detect antibodies to recombinant topoisomerase-I. Antibodies to topoisomerase-I were found in 72 patients (37%) with systemic sclerosis, which is a higher percentage than reported in most previous reports on a large unselected population. In 43 patients the presence of antibodies to recombinant topoisomerase-I was confirmed using both the immunodiffusion method and ELISA, with similar results. When classified into diffuse versus limited disease, a significant difference in antibody prevalence was demonstrated (P < 0.005), thus indicating that anti-topoisomerase-I antibody detection with ELISA may assist in early identification of systemic sclerosis subtypes.

Effect of elective prolonged urethral catheterization on serum prostate-specific antigen concentration

OBJECTIVES

To determine the effect of an indwelling catheter on prostate-specific antigen (PSA) levels. PSA is an organ (prostate)-specific marker, and its level can be elevated in various pathologies as well as following urologic manipulations. An elevated marker may indicate the presence of prostate cancer. In the presence of an indwelling catheter, our inability to decide whether an elevated PSA value represents genuine pathology or is related to the catheter itself is often of great clinical importance.

METHODS

A prospective study was conducted on 21 men with an indwelling catheter inserted electively for major nonurologic abdominal surgery to determine its influence on PSA concentration. Sera were collected before catheter insertion, 2 hours after, and then every day (average, 16 days). Catheters were left in place for an average of 5.5 days.

RESULTS

Follow-up data compared to baseline and to the previous day's PSA concentrations revealed no significant change in any of the subjects. In 2 men with elevated preinsertion PSA levels (more than 10.0 ng/mL), the change over time did not differ in magnitude from changes in the other 19 men with normal pretreatment values.

CONCLUSIONS

Inserting a urethral catheter and maintaining it for several days does not result in any clinically or statistically significant change in PSA levels. PSA values obtained in patients with an indwelling catheter are reliable and independent of its presence. An elevated level mandates prompt evaluation to exclude prostate cancer.

Effects of glutamic acid and related agents on horizontal cells in a marine teleost retina

Excitatory amino acids (EAAs) such as glutamic and aspartic acids, considered as the most likely neurotransmitters at the photoreceptor-horizontal cell synapse of teleost retinas, as well as agonists such as kainic acid and several of their antagonists, were applied to isolated and superfused retinas of the teleost Eugerres plumieri. Intracellular recordings from horizontal cells reveal that EAA receptors are of the kainate-quisqualate type. There is competitive inhibition between the agonist and antagonist agents used, and under their combined effect, the synapse under study remains operational, in a functional state, able to modulate the horizontal cell membrane potential upon retinal illumination.

The psychoanalyst of the adolescent

The adolescent who comes for psychoanalytic treatment has probably experienced a developmental breakdown-a rejection of his or her body and a distorted image of himself or herself as being male or female. A critical requisite for work with such adolescents is an understanding of one's own adolescent development. The internal freedom of the psychoanalyst is an essential ingredient in the treatment of the adolescent. This means that the psychoanalyst of the adolescent can separate his own sexual life and thoughts from what is lived out in the analytic sessions and thus can ensure that the treatment will confront whatever is essential and that he will avoid deriving gratification from the treatment process through taking over the adolescent's body or feeling that he is secretly sharing the intimacies of the patient.

Sexual abuse, or a delusional structure? From adolescent to young adult

The treatment of an adolescent patient who recalled having been sexually abused in childhood by her father is described. In the course of treatment, various doubts were raised in the analyst's mind about the truth of this memory. As the analysis progressed, the analyst felt that the patient's responses to interpretations were signs of the presence of a delusional structure. When the patient felt that the analyst doubted her memory, or was not on her side, she angrily and vengefully broke off her treatment. She remains a very vulnerable young woman. The delusional structure contained the patient's sexual need to destroy the male's potency as a defense against her longing for the oedipal mother who, in reality, had left the patient for a new husband.

Retinal neurotransmitter interaction as reflected in horizontal cell spatial behaviour

The effects of 5-hydroxytryptamine (5-HT) and its precursors 5-hydroxytryptophan (5-HTP) and L-tryptophan (L-Tryp) on the spatial properties of horizontal cells were studied in the isolated and perfused retina of the teleost Eugerres plumieri. All three compounds produce a contraction of the receptive field, evaluated by the ratio of responses evoked by local and distant light stimuli. This is the result of cell uncoupling, revealed by the hindrance to diffusion of intracellularly injected Lucifer yellow. Similar effects are produced by dopamine (DA) and the effectiveness is DA much greater than 5-HT greater than 5-HTP greater than L-Tryp. All these effects are blocked by Haloperidol. HPLC studies of endogenous DA release reveal that it occurs when isolated retinas are incubated with 50 mM potassium, 10 microM 5-HT or 5-HTP, but is not found with up to 1 mM L-Tryp. The results indicate that indolaminergic cells induce the release of DA from interplexiform cells, which in turn uncouples horizontal cells in the fish retina.

Cyclic adenosine monophosphate as a second messenger in horizontal cell uncoupling in the teleost retina

The reduction in the receptive field of horizontal cells of the teleost Eugerres plumieri observed upon dopamine (DA) superfusion is thought to be due to cell uncoupling. The possible mechanisms by which activation of DA receptors modify the electric coupling between horizontal cells were studied in the present work. It was found that the effect of DA in different preparations is mediated by a modification of intracellular concentration of cAMP and H+. The effects of intracellular injection of cAMP and H+ were studied in retinal horizontal cells of the teleost E. plumieri. A triple microelectrode was used to inject the ion iontophoretically, to pass current pulses, and to record voltages from the same cell, while a fourth microelectrode was used to record voltages from a neighboring cell in the same retinal layer. Responses evoked by light spots and annuli were evaluated simultaneously. Coupling ratios between neighboring horizontal cells ranged from 0.22 to 0.45. The intercellular resistance (Rc), 0.5-3.5 x 10(6) ohms, and that of the remaining cell membrane resistance (Rm), 2.5-18 x 10(6) ohms, were calculated by means of a passive electrical model that has a hexagonal array. The microinjection of H+ with injection current from +5 to +30 nA for 40 to 100 sec led to temporary and reversible light response reduction. The coupling ratio between two impaled cells was reduced by about 30%, and intercellular resistance (Rc) increment was 320% while cell membrane resistance (Rm) did not change consistently. There was also a temporary and reversible Rm reduction (70-85%) and an Rc increment of 170-330% when cyclic adenosine monophosphate was iontophoretically injected with current from -30 to -40 nA for 50 to 170 sec. The coupling ratio between two impaled cells was reduced by about 40%, and light responses recorded from the injected cell showed a reduction in amplitude with the same time course as that of the resistive changes. The injection of Lucifer yellow into a horizontal cell under normal conditions always results in pronounced fluorescence for more distant cells; however, under constant injection of H+ or cAMP only the injected cell is fluorescent, which provides direct evidence of the reduction in the effectiveness of coupling between horizontal cells. The observed effects of intracellular H+ or cAMP injection correspond to the resistive changes in Rc and coupling ratio that occur in the horizontal cell network upon superfusion with a dopamine (DA) solution.