Mars Extant Life: What's Next? Conference Report.

On November 5-8, 2019, the "Mars Extant Life: What's Next?" conference was convened in Carlsbad, New Mexico. The conference gathered a community of actively publishing experts in disciplines related to habitability and astrobiology. Primary conclusions are as follows: A significant subset of conference attendees concluded that there is a realistic possibility that Mars hosts indigenous microbial life. A powerful theme that permeated the conference is that the key to the search for martian extant life lies in identifying and exploring refugia ("oases"), where conditions are either permanently or episodically significantly more hospitable than average. Based on our existing knowledge of Mars, conference participants highlighted four potential martian refugium (not listed in priority order): Caves, Deep Subsurface, Ices, and Salts. The conference group did not attempt to reach a consensus prioritization of these candidate environments, but instead felt that a defensible prioritization would require a future competitive process. Within the context of these candidate environments, we identified a variety of geological search strategies that could narrow the search space. Additionally, we summarized a number of measurement techniques that could be used to detect evidence of extant life (if present). Again, it was not within the scope of the conference to prioritize these measurement techniques-that is best left for the competitive process. We specifically note that the number and sensitivity of detection methods that could be implemented if samples were returned to Earth greatly exceed the methodologies that could be used at Mars. Finally, important lessons to guide extant life search processes can be derived both from experiments carried out in terrestrial laboratories and analog field sites and from theoretical modeling.

Microbial contributions to subterranean methane sinks.

Sources and sinks of methane (CH4 ) are critical for understanding global biogeochemical cycles and their role in climate change. A growing number of studies have reported that CH4 concentrations in cave ecosystems are depleted, leading to the notion that these subterranean environments may act as sinks for atmospheric CH4 . Recently, it was hypothesized that this CH4 depletion may be caused by radiolysis, an abiotic process whereby CH4 is oxidized via interactions with ionizing radiation derived from radioactive decay. An alternate explanation is that the depletion of CH4 concentrations in caves could be due to biological processes, specifically oxidation by methanotrophic bacteria. We theoretically explored the radiolysis hypothesis and conclude that it is a kinetically constrained process that is unlikely to lead to the rapid loss of CH4 in subterranean environments. We present results from a controlled laboratory experiment to support this claim. We then tested the microbial oxidation hypothesis with a set of mesocosm experiments that were conducted in two Vietnamese caves. Our results reveal that methanotrophic bacteria associated with cave rocks consume CH4 at a rate of 1.3-2.7 mg CH4  · m-2  · d-1 . These CH4 oxidation rates equal or exceed what has been reported in other habitats, including agricultural systems, grasslands, deciduous forests, and Arctic tundra. Together, our results suggest that depleted concentrations of CH4 in caves are most likely due to microbial activity, not radiolysis as has been recently claimed. Microbial methanotrophy has the potential to oxidize CH4 not only in caves, but also in smaller-size open subterranean spaces, such as cracks, fissures, and other pores that are connected to and rapidly exchange with the atmosphere. Future studies are needed to understand how subterranean CH4 oxidation scales up to affect local, regional, and global CH4 cycling.

The effect of radiation therapy on brain metastases from endometrial carcinoma: a retrospective study.

OBJECTIVE: The objective of this study was to investigate the effectiveness of radiation therapy as a treatment for brain metastases from endometrial carcinoma. METHODS: Between July 1985 and November 1999, 10 patients with brain metastases from endometrial carcinoma were treated at the Cleveland Clinic. We reviewed the patient and tumor characteristics at the time of the primary diagnosis and the brain metastases diagnosis. For the 8 patients who received radiation therapy with or without surgery, we analyzed the treatment results with regard to survival and local control of the metastases. RESULTS: Brain metastases from endometrial carcinoma were commonly accompanied by uncontrolled local-regional disease and systemic metastases. Multiple brain lesions developed in 7 of 10 patients. Two patients were treated with surgery alone and had a median survival of 2.75 months (4 and 1.5 months) after the brain metastases diagnosis. Three patients were treated with surgery and radiation therapy and lived for a median survival of 15 months (range 11.5 to 15.5 months). The 5 patients who were treated with radiation therapy without surgery had a median survival of 2.4 months (range 0.25 to 6 months). Patients with multiple brain metastases had a shorter survival than patients with a single metastasis. CONCLUSION: Overall survival after brain metastases development in patients with endometrial carcinoma was poor. Although the number of patients was small, radiation therapy alone resulted in poor survival. Combination treatment with surgery and radiation therapy may improve survival for selected patients.

Carboplatin skin testing: a skin-testing protocol for predicting hypersensitivity to carboplatin chemotherapy.

PURPOSE: A high incidence of moderate to severe hypersensitivity reactions (HRs) is noted in patients who have been treated with multiple courses of carboplatin. Presently, there is no reliable way to predict which patients may be at risk for this potentially severe adverse reaction. We developed a skin-test protocol to identify patients at high risk for HR to carboplatin chemotherapy. PATIENTS AND METHODS: Patients undergoing more than seven courses of carboplatin received a 0.02-mL intradermal injection of an undiluted aliquot of their planned carboplatin infusion 1 hour before each course of the agent. A positive skin test was prospectively defined as that resulting in a wheel of at least 5 mm with a surrounding flare. We recently reported a 27% incidence of HRs in patients receiving more than seven courses of carboplatin. These patients served as historical controls for the current study. RESULTS: Forty-seven patients with recurrent ovarian or primary peritoneal carcinoma receiving carboplatin were skin tested. Thirteen of 47 patients (28%) manifested a positive skin test at a median of nine total courses of carboplatin (range, eight to 17 courses). This rate of skin-test positivity was not significantly different from the incidence of documented HR reported in a historical control group (P =.89), suggesting comparable populations. A negative skin test accurately predicted the absence of HR in 166 of 168 courses of chemotherapy. Only two of 47 patients (4%) experienced a HR after a negative skin test. Thus, administering carboplatin only to patients with a negative skin test may result in a significant reduction in HRs relative to historical controls (P =.002). CONCLUSION: An easily performed skin test appears to predict patients in whom carboplatin may be safely administered. Treatment modifications based on the results of skin testing may reduce the incidence of HRs in patients receiving repeated courses of carboplatin.

Tumor distribution and survival in six patients with brain metastases from cervical carcinoma.

OBJECTIVE: The aim of this study was to investigate the patterns of brain involvement and the outcome of patients with brain metastases from cervical carcinoma. METHODS: Between January 1982 and November 1999, 1279 patients with brain metastases were treated at the Cleveland Clinic. Six of them had brain metastases from cervical carcinoma. We retrospectively reviewed the patient and tumor characteristics at the time of the primary diagnosis as well as at the time of the brain metastases diagnosis. RESULTS: Brain metastases from cervical carcinoma were rarely accompanied by systemic disease, but they were commonly accompanied by uncontrolled local-regional disease. The median interval from the appearance of the primary carcinoma to the detection of brain metastases in 5 patients was 12 months. Multiple brain lesions developed in 4 of 6 patients and consisted of multiple tumors distributed in the cerebral hemispheres (2 patients) or both the cerebral and the cerebellar hemispheres (2 patients). Only 2 patients had a single lesion confined to a cerebral hemisphere. One patient was treated with stereotactic radiosurgery alone, 3 with surgery followed by whole brain radiation therapy, 1 with whole brain radiotherapy, and 1 each with whole brain radiotherapy and stereotactic radiosurgery. Patients treated with surgery had a median survival of 8.25 months, while patients treated with whole brain radiotherapy with or without stereotactic radiosurgery had a median survival of 3.75 months. The 1 patient treated with stereotactic radiosurgery alone survived for 22.5 months. CONCLUSION: Although the number of the patients was too small to detect definitive patterns of brain metastases from cervical carcinoma, the results of our review suggest that, in contrast to previous reports, extended survival can occur with more aggressive treatment such as surgery or stereotactic radiosurgery.

Paclitaxel, an active agent in nonsquamous carcinomas of the uterine cervix: a Gynecologic Oncology Group Study.

PURPOSE: A phase II trial of paclitaxel was initiated in advanced nonsquamous carcinoma of the cervix to determine its activity in patients who had failed standard chemotherapy. PATIENTS AND METHODS: Eligible patients had at least one measurable lesion. The starting dose of paclitaxel was 170 mg/m(2) (135 mg/m(2) for patients with prior pelvic radiation) given as a 24-hour continuous intravenous infusion with courses repeated every 3 weeks. Dose escalation to 200 mg/m(2) and de-escalation to 110 mg/m(2) were allowed based on adverse effects. RESULTS: In this trial, 42 assessable patients were initially entered onto the study, and 13 responses were seen; four patients had a complete response, and nine patients had a partial response. The overall response rate was 31%. The primary and dose-limiting toxicity was neutropenia. CONCLUSION: The response rate to paclitaxel exceeds the rates reported using other single agents in nonsquamous carcinoma of the cervix.

Treatment of relapsed carcinoma of the ovary with single-agent paclitaxel following exposure to paclitaxel and platinum employed as initial therapy.

OBJECTIVES: The aim of this study was to evaluate the ability of paclitaxel to achieve a second clinical response in patients with recurrent epithelial ovarian carcinoma who responded to standard therapy with platinum and paclitaxel in the initial setting. METHODS: Thirty-four patients with epithelial ovarian who demonstrated a complete response to paclitaxel and platinum in the initial treatment setting were retreated with paclitaxel as a single agent for relapse of their disease. Paclitaxel was given at a dose of 135-175 mg/m(2) over 3 h at 21-day intervals. Fifteen patients had platinum-resistant disease and 19 had potentially platinum-sensitive disease. Response was documented by physical examination, serial serum CA125 measurement, or radiologic evaluation. RESULTS: An objective response to paclitaxel retreatment was demonstrated in 15 patients (44%), with a median progression-free interval (PFI) of 8.6 months (range 4-17 months). An additional 14 patients (41%) demonstrated disease stabilization, with a median PFI of 7.4 months (range 3-13 months). Overall, retreatment with paclitaxel was well tolerated, with minimal cumulative toxicities, despite repetitive dosing. CONCLUSION: These results demonstrate that patients with ovarian cancer who relapse after initial treatment with paclitaxel often have disease that is still responsive to the agent. Given its relative lack of cumulative toxicity, retreatment with paclitaxel as a single agent is a reasonable therapeutic option for patients with recurrent ovarian cancer.

Safety and efficacy of adjuvant single-agent ifosfamide in uterine sarcoma.

PURPOSE: The role of adjuvant therapy for completely resected uterine sarcoma continues to be debated. Previous chemotherapy trials have shown little, if any, advantage over surgery alone, with significant added toxicity. To our knowledge, the current study is the first to evaluate adjuvant ifosfamide in completely resected uterine sarcomas. METHODS: Between 1992 and 1999, 13 consecutive patients with completely resected moderate- to high-grade uterine sarcoma received three cycles of adjuvant ifosfamide (1.5 g/m(2)/day x 3 days, repeated every 28 days). Mesna was given 30 min prior to infusion. Postinfusion mesna was administered to 10 of the patients in the outpatient setting utilizing a subcutaneous infusion pump. The remaining 3 patients received traditional intravenous mesna at 4 and 8 h after infusion. RESULTS: The median follow-up of the patient population was 26 months. For early-stage patients (n = 10), the 2-year progression-free survival was 60%, with a median of 26 months. The 2-year overall survival was 100%, dropping to 67% at 3 years. Early-stage patients showed an advantage in both progression-free and overall survival. Early-stage patients with mixed müllerian tumor (MMT) had a significantly longer time to progression that those with leiomyosarcoma (LMS) (2-year progression-free survival of 100% versus 33%; P = 0.019). Three patients required dose reduction secondary to grade 2-3 toxicities (neutropenia x2, nausea and vomiting x1). All significant toxicity was eliminated with dose reduction. CONCLUSIONS: Adjuvant ifosfamide appears to be safe and well tolerated in patients with completely resected uterine sarcoma. It can easily be given in the outpatient setting if mesna is administered via a subcutaneous pump. Our data, consistent with previous studies in advanced sarcoma, suggest a potentially greater role for ifosfamide in MMT than in LMS.

The use of paclitaxel and platinum-based chemotherapy in uterine papillary serous carcinoma.

OBJECTIVE: Uterine papillary serous carcinoma (UPSC) is an aggressive malignancy with a histologic appearance and pattern of spread that resembles that of papillary serous adenocarcinoma of the ovary. The current standard therapy for advanced ovarian cancer, cisplatin or carboplatin plus paclitaxel, results in high objective response rates for that tumor. This regimen has thus far not been evaluated in UPSC. METHODS: Twenty-four patients with UPSC treated with platinum-based chemotherapy and paclitaxel were retrospectively evaluated. Eighteen patients received these agents in the adjuvant setting (n = 9) or for disease persistent after initial surgical management (n = 9). Eleven patients received one or more courses of this drug combination for recurrent disease, 5 of whom had prior exposure in the initial setting. RESULTS: Mean follow-up was 35 months (range 6-72+). A median progression-free interval (PFI) of 30 months (range 8-61+) was seen in patients treated in the adjuvant setting. Objective response, indicated by normalization of an elevated prechemotherapy CA125 level, was seen in 8 of 9 patients treated for residual disease after initial surgery (median PFI of 13 months, range 5-38+). Objective response of both measurable and/or evaluable disease was seen in 7 of 11 patients treated for recurrent disease (median PFI of 9 months, range 4-18). Six patients had retreatment with one or both agents and 4 responded a second time. Overall, the regimen was well tolerated. CONCLUSION: Paclitaxel and platinum-based chemotherapy has demonstrated activity in UPSC with acceptable toxicity. These results merit further investigation of the possible role of these agents in patients with this aggressive histologic subtype.

In vitro studies on the release of morphine sulfate from compounded slow-release morphine-sulfate capsules.

Morphine sulfate is a commonly prescribed drug for the relief of pain. This study investigated the dissolution profile of extemporaneously prepared slow-release morphine-sulfate capsules and MS Contin (Purdue Frederick, Norwalk, CT). Extemporaneously prepared capsules obtained from one pharmacist were compared with MS Contin tablets. In addition, we compared capsules prepared by 15 different pharmacists and three different batches prepared by the same phaarmacist. A dissolution test was used to generate the dissolution profile for drug products. The compounded capsules demonstrated a slow-release profile that was similar to the commercial preparation except that the morphine sulfate was released at a faster rate. The zero-order dissolution rate constant (k0, milligrams/hour) was calculated from the dissolution profiles. Statistical analysis of k0 showed that caapsules prepared extemporaneously by pharmacist one showed a faster dissolution compared to MS Contin (p=0.0368); the difference was a rate of 0.81 mg/hour during the first four hours. When variability among compounding pharmacists was compared, only one batch of compounded capsules prepared from 15 different pharmacies showed a significantly different rate of morphine release. When reproducibility by a single pharmacist was examined, capsules showed some variation from batch to batch (p=0.05). Although variation was seen from one pharmacy to another and even between different batches made by the same pharmacist, the compounded capsules showed a remarkably consistent in vitro slow-release profile.

Experience with platinum-paclitaxel chemotherapy in the initial management of papillary serous carcinoma of the peritoneum.

OBJECTIVE: The objective of this study was to assess the activity and toxicity of combination platinum-paclitaxel chemotherapy in the initial management of patients with papillary serous carcinoma of the peritoneum (PSCP). METHODS: Patients initially treated at The Cleveland Clinic Foundation (CCF) for PSCP with platinum-paclitaxel combination chemotherapy regimens were identified and clinical information was abstracted by chart review. Toxicity data, progression-free survival, and overall survival were determined. RESULTS: Thirty-eight patients (36 Stage IIIC and 2 Stage IV) were identified. All chemotherapy was administered as outpatient infusions. All patients received paclitaxel (135 or 175 mg/m2) and 12 received cisplatin and 26 carboplatin. Two hundred thirty-two cycles were administered, with only three (1.3%) episodes of grade 3 toxicity and no grade 4 toxicity. Ninety-two percent of patients experienced at least a 50% reduction in their CA-125 levels and 55% experienced a greater than 90% reduction. Median progression-free survival (Kaplan-Meier) was 15 months and median overall survival was 40 months. Survival for optimally debulked patients (median not yet reached with median follow-up of 24 months) was significantly better than for suboptimally debulked patients (median 32.8 months) (P = 0.012). CONCLUSION: Platinum-paclitaxel chemotherapy regimens have substantial utility in the initial management of PSCP patients. The toxicity profile is modest. Carboplatin or cisplatin in conjunction with paclitaxel is the current first-line recommended chemotherapy for PSCP.

Phase II trial of 5-fluorouracil and high-dose leucovorin in recurrent adenocarcinoma of the cervix: a Gynecologic Oncology Group study.

OBJECTIVE: The objective of the study was to determine the response rate and associated toxicity of 5-fluorouracil and high-dose leucovorin in patients with recurrent adenocarcinoma of the cervix. METHODS: Between December 1993 and October 1995, 53 patients with recurrent adenocarcinoma of the cervix were entered into a Phase II trial utilizing 200 mg/m2 of intravenous (iv) leucovorin with 370 mg/m2 of i.v. 5-fluorouracil daily for 5 days every 4 weeks for two courses, then every 5 weeks until disease progression. Eligibility criteria were a Gynecologic Oncology Group (GOG) performance status of 0-2, adequate bone marrow reserve, adequate liver function with bilirubin < or = 1.5 x normal and SGOT and alkaline phosphatase < or = 3 x normal, serum creatinine < or = 2 mg%, and signed informed consent. Standard GOG toxicity and response criteria were employed. RESULTS: Six patients were ineligible because of wrong cell type (N = 3), insufficient pathology materials (N = 2), or a second primary (N = 1); therefore 45 were evaluable for toxicity. Two patients did not have adequate response assessment; thus, 43 were evaluable for response. The median age was 50 (range, 28-79). Prior chemotherapy had been administered to 16 patients and radiotherapy to 40 patients. The median number of courses delivered was three (range, 1-22). The site of evaluable disease was pelvic in 25 patients and extra-pelvic in 18. Grade 3 neutropenia was seen in 17.8% (8/45) patients and 35.5% (16/45) developed grade 4 neutropenia. Grade 3 or 4 thrombocytopenia was seen in 1 patient each (2.1%). Grade 3 gastrointestinal toxicity with nausea, vomiting, diarrhea, dehydration, or stomatitis was of grade 3 severity in 11.1% (5/45) and grade 4 in 6.7% (3/45). There were four partial responses and two complete responses for an overall response rate of 14%. The duration of the complete responses was 17.3 and 8.8+ months. None of the patients with responses had previously received chemotherapy. CONCLUSION: The schedule of 5-fluorouracil and leucovorin exhibits moderate activity in patients with previously treated adenocarcinoma of the cervix and should be considered for a trial in chemotherapy-naive patients.

A phase II trial of prolonged oral etoposide (VP-16) as second-line therapy for advanced and recurrent endometrial carcinoma: a Gynecologic Oncology Group study.

Prolonged oral etoposide is an active regimen in small and nonsmall cell carcinoma of the lung, carcinomas of the breast and ovary, germ cell tumors, and in lymphoma. A Phase II trial was conducted by the Gynecologic Oncology Group to determine its activity in endometrial carcinoma. Twenty-six patients with advanced or recurrent endometrial carcinoma were entered into study; one patient was ineligible because of an incorrect cell type. The remaining eligible patients were treated with etoposide at a starting dose of 50 mg/m2/day (30 mg/m2/day with prior radiotherapy) for 21 days. Based on hematologic toxicity, a dose escalation to a maximum dose of 60 mg/m2/day was prescribed. Twenty-two patients were evaluable for response and 25 were evaluable for toxicity. Fourteen had received prior radiotherapy and 24 had received prior chemotherapy. A median of two courses were given (range, 1-10). Grade 3 or 4 leukopenia occurring in 52% was the most common complication (grade 3, 36%; grade 4, 16%). Grade 4 thrombocytopenia occurred in 16% of patients. There were no objective responses including four patients with serous papillary carcinoma. This regimen is not significantly active as second-line therapy in endometrial carcinoma.

Radical hysterectomy for cervical cancer: the effect of shorter length of stay on outcome.

BACKGROUND: The surgical treatment for limited cervical cancer (radical hysterectomy and pelvic lymph node dissection) has remained essentially the same for 40 years, but economic pressures have resulted in shorter length of hospital stay, and precautions against infectious diseases have resulted in less use of blood products. PURPOSE: To determine if recent changes in hospital practices have affected outcomes, and if obese patients are at greater risk of complications. METHODS: Retrospective review of 100 surgical cases grouped by time period (1981 through 1987 and 1988 through 1993) and by patient weight (< 80 kg and > or = 80 kg). RESULTS: Comparing the two time periods, the mean operative time remained the same (199 minutes), but use of blood products declined (mean 2.1 vs 1.5 units; P < .01), as did the mean length of hospital stay (10.6 vs 7.4 days, P < .01). The rate of postoperative complications decreased significantly (P < .01), and the 5-year survival rate remained 91%. Obese patients received more blood transfusions than did nonobese patients (2.6 vs 1.6 units; P = .02), but their mean operative time and hospital stay did not significantly differ. The rate of postoperative and long-term complications did not differ significantly between the two weight groups. CONCLUSIONS: Surgical treatment of limited cervical carcinoma continues to be safe and effective.

Immunity to potato mop-top virus in Nicotiana benthamiana plants expressing the coat protein gene is effective against fungal inoculation of the virus.

Nicotiana benthamiana stem tissue was transformed with Agrobacterium tumefaciens harboring a binary vector containing the potato mop-top virus (PMTV) coat protein (CP) gene. PMTV CP was expressed in large amounts in some of the primary transformants. The five transgenic lines which produced the most CP were selected for resistance testing. Flowers on transformed plants were allowed to self-fertilize. Transgenic seedlings selected from the T1 seed were mechanically inoculated with two strains of PMTV. Virus multiplication, assayed by infectivity, was detected in only one transgenic plant of 98 inoculated. T1 plants were also highly resistant to graft inoculation; PMTV multiplied in only one plant of 45 inoculated. Transgenic T1 seedlings were challenged in a bait test in which they were grown in soil containing viruliferous spores of the vector fungus Spongospora subterranea. In these tests only two plants out of 99 became infected. Of the five transgenic lines tested, plants of three lines were immune to infection following manual, graft, or fungal inoculation.

Enhancement of resistance to potato leafroll virus multiplication in potato by combining the effects of host genes and transgenes.

Four potato clones with host gene-mediated resistance to potato leafroll virus (PLRV) multiplication were transformed with the PLRV coat protein (CP) gene. Plants of lines expressing high levels of transcript were highly resistant to PLRV multiplication; virus concentration was only 20-40 ng/g of leaf, which is approximately 1% of the concentration reached in susceptible cultivars. The effects of the transgenic and host-derived resistance genes appear to be additive.

Clarification of the structure of the ampicillin-resistance plasmid RSF0885 from Haemophilus influenzae HR-885 serotype b.

The nonconjugative ampicillin-resistance plasmid RSF0885 has been reported to be as small as 2.9 MDa and as large as 4.1 MDa with at least two restriction enzyme maps reported. In addition, the source of the original plasmid has been reported to be Haemophilus influenzae and Haemophilus parainfluenzae. Characterization of the source strains and sequencing data of the plasmids revealed that H. influenzae serotype b was the original source strain and that IS1-K in the larger plasmid was presumably acquired when the smaller plasmid was maintained in Escherichia coli in S. Falkow's laboratory during the late 1970s.

Circadian-timed combination doxorubicin-cisplatin chemotherapy for advanced endometrial carcinoma. A phase II study of the Gynecologic Oncology Group.

Patients with advanced or recurrent endometrial cancer of any cell type having measurable disease have been entered into this study to determine the effectiveness and toxicity of circadian-timed doxorubicin-cisplatin chemotherapy. This Phase II study involved no randomization with treatment initiated with doxorubicin 60 mg/m2 over 30 minutes at 6:00 a.m., followed by cisplatin 60 mg/m2 over 30 minutes at 6:00 p.m. every 28 days. Treatment was continued for eight cycles or to a maximum tolerable doxorubicin dose of 480 mg/m2 for patients without progression. Thereafter, responders continued on cisplatin alone. A review of 30 evaluable patients showed 6 (20%) complete responses, 12 (40%) partial responses, and 7 (23%) with stable disease. The number of treatment courses ranged from 2 to 14 with a median of 6.5. the median white blood cell nadir for the 27 patients experiencing leukopenia was 1,600/mm3 (range: 300-3,600/mm3) For the 16 patients experiencing thrombocytopenia the median nadir was 48,500/mm3 (range: 8,000-138,000/mm3). There were no treatment-related deaths. Circadian-timed delivery of doxorubicin-cisplatin chemotherapy was reasonably well tolerated and demonstrated notable response rates in patients with advanced or recurrent endometrial carcinoma.