Human trabecular meshwork cell survival is dependent on perfusion rate

PURPOSE

To determine whether suppression of flow may be detrimental to trabecular cell survival and to the morphologic characteristics of the trabecular meshwork.

METHODS

The anterior segments of normal human eye bank eyes were placed in perfusion organ culture. The effect of various perfusion rates of culture medium, and of the constant flow and constant pressure methods of delivery of culture medium, were studied. Trabecular cell survival was determined by quantitation of cell nuclei in histologic sections and by morphologic observation.

RESULTS

Trabecular meshworks with perfusion rates of 1 microliter/minute and higher had significantly more trabecular cells than meshworks with lower perfusion rates. A significant loss of trabecular cells was found in meshworks cultured with the constant pressure technique when compared with fellow eyes cultured with the constant flow of medium. Those constant pressure cultured meshworks with surviving cells had higher flow rates than those with necrotic cells.

CONCLUSIONS

A minimum perfusion rate of 1 microliter/minute is required for trabecular cell survival in perfusion organ culture. Constant pressure perfusion of medium is unsuccessful in maintaining trabecular cells in long-term culture if low perfusion rates occur. Constant flow appears to mimic the in vivo situation more closely.

Fractal noise strength in auditory-nerve fiber recordings

Discharge patterns recorded from single auditory-nerve fibers have demonstrated long-range dependence, with the count variance-to-mean ratio growing as a power of the counting time for times greater than 0.1-1 s. The intent of this study is to provide a large dataset to enable a more detailed investigation of this phenomenon. Based on 108 recordings from a cat, we conclude that the presence of the fractal noise in the discharge rate is independent of characteristic frequency and stimulus level, but does depend on discharge rate. We measured the low-frequency power of the fractal noise, finding its coefficient of variation to range between 6% and 26% and to decrease as firing rate increases. Such behavior is consistent with multiplicative fractal variations in models of the hair cell membrane permeability to neurotransmitter. Measured standard deviations of spike rate correspond to a sound-pressure level difference limen of approximately 1 dB.

Drug fever

Drug fever is the febrile response to a drug without cutaneous manifestations. Although the exact incidence of drug fever remains unknown, it has been estimated to occur in approximately 10% of inpatients. The recognition of drug fever is of great clinical importance because, if drug fever is not recognized diagnostically, patients may be subjected to prolonged hospitalization and unnecessary testing or medications. Early diagnosis and treatment of drug fevers are essential in maintaining cost-effective, high-quality medical care.

Carcinoid tumor and the nephrotic syndrome: a novel association between neoplasia and glomerular disease

Various malignancies are associated with the paraneoplastic evolution of the nephrotic syndrome. Renal biopsy in these instances frequently shows membranous glomerulonephritis. We describe a patient who had metastatic bronchial carcinoid tumor with development of microscopic hematuria and subsequent nephrotic syndrome in conjunction with another paraneoplastic process, a malignancy-related neuropathy. A decline in actual glomerular filtration rate led to percutaneous renal biopsy, which revealed fine holes in the glomerular basement membrane and focal capillary corrugation. Electron microscopy showed numerous small subepithelial dense deposits and fusion of foot processes, confirming the diagnosis of stage I membranous nephropathy. We believe this is the first published case of true carcinoid tumor associated with the nephrotic syndrome and a specific paraneoplastic glomerular lesion. Carcinoid tumor should be considered in the spectrum of malignancies associated with paraneoplastic development of the nephrotic syndrome.

Paclitaxel and 5-fluorouracil in metastatic breast cancer: the US experience

Paclitaxel (Taxol; Bristol-Myers Squibb Company, Princeton, NJ) is an effective drug in the treatment of metastatic breast cancer (MBC). In the salvage setting, 5-fluorouracil (5-FU) and folinic acid have proved to be effective against MBC as well. Recent preclinical data suggest that paclitaxel plus 5-FU has additive cytotoxicity. Given these observations, we initiated a phase II trial in which 38 women with MBC have been treated with a combination of all three drugs. All patients are currently evaluable for toxicity and 34 are evaluable for response. All women had histologically proven and assessable disease. Patients with prior exposure to paclitaxel were ineligible. Patient characteristics include a median age of 51 years (age range, 31 to 73 years) and a median performance status of 1 (range, 0 to 2). Thirty-three patients have received prior chemotherapy, of whom 23 had adjuvant chemotherapy only. Fifty-eight percent of the patients (22 of 38) had received prior doxorubicin or mitoxantrone; four patients had only hormonal therapy. Four patients had bone-only disease, and three patients had lymphangitic spread or cytologically positive pleural effusion as the only evaluable disease. Treatment consisted of paclitaxel 175 mg/m2 over 3 hours (day 1 only), followed by folinic acid 300 mg over 1 hour, followed by 5-FU 350 mg/m2 on days 1 to 3. Patients received standard paclitaxel premedications. To date, 175 cycles have been administered (median cycle length, 29 days; median number of cycles per patient, five). Toxicities included grade 3/4 infections in nine cycles (5%), grade 3/4 mucositis in three cycles, grade 3/4 nausea/vomiting in three cycles, grade 1 paresthesias in 12 patients (32%), alopecia 100%, and 17 cycles (10%) associated with dose reduction. Based on Cancer and Leukemia Group B toxicity criteria, arthralgia/myalgias were modest and graded mild (32 cycles), moderate (nine cycles), or severe (two cycles). There were two major hypersensitivity reactions, prompting removal of those patients from further protocol treatment. Four patients are unassessable for response due to hypersensitivity reactions (two) and unevaluable disease (two). Among the 34 patients evaluable for response, there were three complete responses, 18 partial responses, one minor response, nine stable disease, and three progressive disease (response rate, 62%). Responses were seen in patients who had received prior doxorubicin or mitoxantrone (11 of 22 patients) and in anthracycline/naive patients (10 of 16 patients). Responses were observed in all metastatic sites: soft tissue, viscera, and bone. Paclitaxel/5-FU/folinic acid appears to be an effective and well-tolerated outpatient regimen for women with MBC, even after failure of anthracycline-containing therapy.

Effect of fixation pressure on juxtacanalicular tissue and Schlemm's canal

PURPOSE

A quantitative study was performed to compare the effect of two commonly used fixation pressures, 0 mm Hg (immersion) and 10 mm Hg (perfusion), on the porosity of the juxtacanalicular tissue and the size of Schlemm's canal.

METHODS

Twelve pairs of human eyes were studied by fixing one eye with perfusion fixation and the fellow eye with immersion fixation. Morphometric analysis of the juxtacanalicular tissue and Schlemm's canal was performed. Outflow resistance was calculated from these measurements and compared with the measured outflow resistance obtained in six eyes.

RESULTS

Schlemm's canal was narrowed in perfusion-fixed eyes, with a 47% smaller cross-sectional area than in immersion-fixed eyes (P = 0.04). Juxtacanalicular tissue of perfusion-fixed eyes had a 13.4% increase in the relative amount of empty space when compared with immersion-fixed fellow eyes (P = 0.04). Solid tissue components were almost equally divided among amorphous basement membrane, tendon and sheath material, and cytoplasm. No obvious washout of extracellular material was noted in perfused tissue. Measured outflow resistance was 100 times larger than outflow resistance of the juxtacanalicular tissue calculated from histologic measurements.

CONCLUSIONS

Perfusion fixation at physiologic intraocular pressure caused a 47% decrease in the area of Schlemm's canal and a mean increase of 13.4% in the relative amount of empty space in the juxtacanalicular tissue compared with immersion-fixed fellow eyes. Perfusion of fixative did not appear to cause washout of extracellular material. Perfusion-fixed tissue appears preferable for studies of Schlemm's canal and for ultrastructural studies of the aqueous outflow pathways within the juxtacanalicular tissue.

Transient effects during the chopping response of LSO neurons

The initial transient chopping response of LSO neuron discharges to both monaural and binaural tone-burst stimuli in the context of a previously developed point process model of the later sustained response is analyzed and modeled. The analysis reveals the nature of the initial transient response to stimulus onset: The model's stimulus-dependent parameters vary with poststimulus-onset time while the neuron's intrinsic recovery characteristics remain constant throughout the response. By applying maximum-likelihood estimation techniques to determine the time course of the stimulus-dependent parameters, it was found that the initial excitatory and inhibitory effects decay exponentially, with their ratio determining the instantaneous rate of firing and their relative latency determining the extent of the initial chopping pattern. The "absolute" and apparent deadtime also vary exponentially during the transient portion of the response. It is concluded that the recovery characteristics of LSO neurons and, the exponential nature of the transient effects give rise to a tightly distributed latency period and a regular chopping response pattern that could encode azimuthal information.

Paclitaxel plus carboplatin for advanced lung cancer: preliminary results of a Vanderbilt University phase II trial--LUN-46

Based on their good activity and minimal toxicity in non-small cell lung cancer and other cancers, we initiated a phase II trial of carboplatin plus paclitaxel (Taxol; Bristol-Myers Squibb Company, Princeton, NJ) in the treatment of patients with previously untreated stage IIIB and IV non-small cell lung cancer. Among 51 patients treated, the overall response rate was 27.5% (14 partial responses). Seventeen patients had stable disease, while 16 patients experienced disease progression after two cycles of treatment. Apart from myelosuppression, toxicity has been modest, with fewer than 5% of patients experiencing grade 3 or greater nonhematologic toxicity. Objective response and survival rates were modestly improved among patients given the higher of two paclitaxel doses (175 mg/m2 v 135 mg/m2). These data suggest that paclitaxel plus carboplatin warrants further study in metastatic non-small cell lung cancer.

Aztreonam

Aztreonam is a monocyclic beta-lactam antibiotic that is active exclusively against the aerobic gram-negative bacilli. It is not ototoxic or nephrotoxic and so is used as an alternative to aminoglycosides in a variety of clinical situations. In polymicrobial infections or when used for empiric therapy, aztreonam must be combined with other antimicrobial agents active against gram-positive and anaerobic species. Aztreonam is often effective against resistant strains of gram-negative organisms, which are often involved in nosocomial infections. Overuse of aztreonam should be avoided to prevent the emergence of resistant P. aeruginosa strains. Except in the treatment of P. aeruginosa infections, aztreonam should not be added to beta-lactam regimens for additional gram-negative coverage.

Bilateral suppurative thrombophlebitis due to Staphylococcus aureus

Suppurative thrombophlebitis is an infection of the wall of a superficial vein, usually is associated with intravenous catheter placement, and accounts for about 10% of all nosocomial infections. Suppurative thrombophlebitis occurs most commonly in patients with burns, patients with cancer, and persons receiving steroids. Skin flora organisms (e.g., Staphylococcus aureus and to a lesser extent Enterobacteriaceae) are the most common pathogens. Suppurative thrombophlebitis should be suspected when a patient having phlebitis presents with a temperature of 102 degrees F or higher. The diagnosis of suppurative thrombophlebitis is usually straightforward and made by demonstration of pus coming from the wound of the removed intravenous device or by aspiration of pus percutaneously from the involved vein. Treatment of superficial suppurative thrombophlebitis consists of venotomy of the affected vessel and systemic antimicrobial therapy. We present a case of S. aureus bilateral suppurative thrombophlebitis, which is most unusual.

Phase II study of ifosfamide, carboplatin, and oral etoposide chemotherapy for extensive-disease small-cell lung cancer: an Eastern Cooperative Oncology Group pilot study

PURPOSE

A phase II study of ifosfamide, carboplatin, and prolonged oral administration of etoposide (ICE) in patients with untreated extensive-disease (ED) small-cell lung cancer (SCLC) was conducted to assess toxicities, response, and median survival.

PATIENTS AND METHODS

Between July 1990 and August 1992, 35 patients were treated. ICE doses were ifosfamide 5 g/m2 by 24-hour continuous intravenous (CIV) infusion with mesna on day 1, carboplatin 300 mg/m2 intravenously (IV) on day 1, and etoposide 50 mg/m2 orally on days 1 to 21 every 4 weeks for up to six to eight cycles (schedule I). Because of severe hematologic toxicity in the first 18 patients, the last 17 patients received ifosfamide 3.75 mg/m2 IV on day 1, carboplatin 300 mg/m2 IV on day 1, and etoposide 50 mg orally on days 1 to 14 (schedule II).

RESULTS

Nine of 18 patients (50%) on schedule I had 13 episodes of severe hematologic toxicity (one death), and only two (11%) received full doses on cycle 2. However, with schedule II, only four of 17 patients (24%) developed severe hematologic toxicity, and eight (47%) received full doses on cycle 2. Objective responses were observed in 29 of 35 patients (83%) (schedule 1, 16 of 18 patients [89%]; schedule II, 13 of 17 patients [76%]). There were eight (23%) complete responses (CRs) and 21 (60%) partial responses (PRs). The median survival duration was 8.3 months, and 1- and 2-year survival rates were 37% and 14%, respectively.

CONCLUSION

ICE with oral etoposide has comparable activity with other regimens in ED SCLC. However, the 2-year survival rate may be higher and ICE with the lower doses of schedule II could be given safely with acceptable toxicity. Further studies of ICE compared with standard two-drug regimens are warranted.

Future directions in the management of small cell lung cancer

The treatment of small cell lung cancer (SCLC) has continued to evolve over the past 20 years and now consists primarily of combination chemotherapy with or without thoracic radiotherapy depending on stage at presentation. However, despite marked improvement in overall survival, a majority of patients continue to die of their disease. It is not likely that conventional chemotherapy agents will substantially alter this dismal fact but new agents are available with novel mechanisms of action some of which yield excellent response rates. The agents with greatest promise include the taxanes and drugs that target topoisomerase I. Real progress in the management of SCLC will come with the identification of methods for overcoming drug resistance, exploration of new treatment strategies including gene therapy and possibly through the use of biological agents. Chemoprevention trials are of the utmost importance given the high incidence of second primary tumors that arise in the few long term survivors of this disease. All these areas are fertile grounds for future investigation in the management of SCLC.

Phase II study of paclitaxel in patients with extensive-disease small-cell lung cancer: an Eastern Cooperative Oncology Group study

PURPOSE

To evaluate the efficacy and safety of paclitaxel (Taxol; Bristol-Myers Squibb Co, Princeton, NJ), a novel diterpene plant product in the treatment of previously untreated patients with extensive-disease small-cell lung cancer (SCLC).

PATIENTS AND METHODS

Patients with extensive-disease SCLC received paclitaxel 250 mg/m2 intravenously over 24 hours every 3 weeks. Nonresponders or partial responders, who received the maximum number of cycles (n = 4) of paclitaxel received salvage chemotherapy that consisted of etoposide (VP-16) 120 mg/m2 intravenously over 45 minutes on days 1, 2, and 3, and cisplatin 60 mg/m2 intravenously as a short infusion on day 1. Cycles were repeated every 3 weeks.

RESULTS

Of 36 patients entered onto the study, 34 and 32 patients were assessable for toxicity and response, respectively. No complete responses (CRs) were observed. Eleven patients (34%) had a partial response (PR) and six (19%) had stable disease (SD). In three of six patients categorized as having SD, there was greater than 50% tumor shrinkage. However, no 4-week follow-up measurements were made, so these could not be considered PRs, in part because patients received salvage chemotherapy by study design. In this trial, induction and salvage chemotherapy resulted in a response (two CRs and 15 PRs) (53%) in 17 patients. The estimated median survival duration was 43 weeks. Dose-limiting toxicity was leukopenia, with 19 patients (56%) having grade 4 leukopenia. The numbers of patients who experienced other grade 4 toxicities were as follows: pulmonary, three (9%); liver, two (6%); cardiac, one (3%); thrombocytopenia, one (3%); metabolic, one (3%); stomatitis, one (3%); and allergic reaction, one (3%). Four additional patients had grade 3 leukopenia and one patient (3%) died of sepsis (grade 5 toxicity).

CONCLUSION

Paclitaxel is an active new agent in the treatment of SCLC. Further investigation of this agent in combination with other active agents is appropriate.

Induction but not expression of behavioural sensitization to nicotine in the rat is dependent on glucocorticoids

Behavioural sensitization has been implicated in the development of addictive behaviour, and several studies suggest that corticosteroids may be involved in this phenomenon. In the present study, the effects of adrenalectomy and steroid replacement treatments on the behavioural sensitization observed after daily injections of nicotine (0.4 mg/kg s.c.) were investigated in the rat. Adrenalectomy completely prevented sensitization to the locomotor stimulating effect of nicotine after repeated injections but did not influence the acute locomotor activating effect of the drug or an already established sensitization to nicotine. In adrenalectomized animals receiving replacement treatment with corticosterone or dexamethasone, but not aldosterone, repeated administration of nicotine produced behavioural sensitization. Repeated dexamethasone treatment per se failed, however, to sensitize rats to nicotine. Post mortem neurochemical studies showed that repeated administration of nicotine significantly increased homovanillic acid (HVA) levels, as well as the dihydroxyphenylacetic acid (DOPAC)/dopamine quotient, in the limbic forebrain. Adrenalectomy per se significantly increased HVA levels and tended to elevate the DOPAC/dopamine quotient. When repeatedly treated with nicotine, adrenalectomized rats displayed a higher DOPAC/dopamine quotient, but no significant difference in HVA levels, compared to nicotine-treated sham-operated controls. In the striatum and the cortex, no significant effects of nicotine treatment or adrenalectomy were observed on any of the neurochemical measures. The present results suggest that glucocorticoid (type II) receptor activation is required for induction of sensitization to the locomotor stimulatory effect of nicotine, whereas corticosteroids are not required for the expression of the behavioural sensitization once established. Provided that HVA levels and the DOPAC/dopamine quotient relatively well reflect the presynaptic dopamine activating effect of nicotine, it may be suggested that corticosteroid-related mechanisms associated with behavioural sensitization to nicotine are post- rather than presynaptically located in relation to mesolimbic dopamine neurons.

Combined modality therapy in non-small cell lung cancer

Lung cancer kills more Americans annually than the next four most frequently diagnosed malignancies combined. Single-modality therapy is the standard for most cases of limited and metastatic non-small cell lung cancer, but treatment of locally advanced disease remains controversial. Historically, radiotherapy alone was used; more recent approaches include single-agent or combination chemotherapy. The combined chemoradiotherapy approach, versus single-modality chemotherapy or irradiation, has improved on survival. Investigators have also recently shown an advantage to adding chemotherapy with or without radiotherapy to definitive surgery. Better staging systems and definitions of biologic prognostic factors may help determine the optimal therapy for locally advanced non-small cell lung cancer patients.

Adjuvant chemotherapy for non-small cell lung cancer

In the late 1970s and early 1980s, the Lung Cancer Study Group conducted a series of adjuvant chemotherapy trials in patients with resected non-small cell lung cancer. Although some of these trials yielded modest survival benefit, the length of improved survival essentially equaled the time spent receiving chemotherapy. Consequently, few physicians routinely employ postoperative chemotherapy in spite of its theoretical appeal. Possible explanations for the failure of adjuvant chemotherapy to provide meaningful prolongation of survival in non-small cell lung cancer include lack of effective chemotherapy, incorrect chemotherapy regimen, inadequate dose intensity, and possibly inadequate trial design. Future postoperative adjuvant trials should focus on treating patients with resected early stage lesions (T1N1, T2N1, T2N0). What role, if any, newer antineoplastic agents will play in the postoperative setting remains to be determined. Neoadjuvant induction chemotherapy may well prove to be a superior treatment strategy and deserves further investigation.

Significant activity of paclitaxel in advanced transitional-cell carcinoma of the urothelium: a phase II trial of the Eastern Cooperative Oncology Group

PURPOSE

To assess the efficacy and toxicity of single-agent paclitaxel as first-line chemotherapy in patients with locally advanced or metastatic transitional-cell carcinoma of the urothelium.

PATIENTS AND METHODS

Twenty-six eligible patients were enrolled onto this cooperative group study and treated with paclitaxel at a dosage of 250 mg/m2 by 24-hour continuous infusion every 21 days until progression or patient intolerance. All patients received recombinant human granulocyte colony-stimulating factor (rhG-CSF) at 5 micrograms/kg/d for at least 10 days during each cycle.

RESULTS

Eleven of 26 patients (42%; 95% confidence interval [CI], 23% to 63%) demonstrated an objective response, with seven achieving a complete clinical response (CR) (27%; 95% CI, 12% to 48%) and four (15%) a partial response (PR). The median duration of response in the 11 responders is 7+ months (range, 4 to 17), with five responders (four CRs, one PR) remaining progression-free at 5, 6, 10, 12, and 16 months from the start of therapy. The estimated median survival duration for all patients is 8.4 months. Hematologic toxicity consisted of anemia (12% grade 3) and granulocytopenia (4% grade 3, 19% grade 4), with two patients developing granulocytopenic fevers. Nonhematologic toxicity included grade 3 mucositis in 11%, grade 3 neuropathy in 11%, and grade 4 diarrhea in 4%.

CONCLUSION

Single-agent paclitaxel at this dosage and schedule is one of the most active single agents in previously untreated patients with advanced urothelial carcinoma, and is well tolerated by this patient population when given with hematopoetic growth factor support.