Culturing and bioassay testing of Daphnia magna using Elendt M4, Elendt M7, and COMBO media.

A performance-based, tiered approach was used to evaluate survival, growth, and reproduction of Daphnia magna in three selected synthetic media: Elendt M4, Elendt M7, and COMBO. Both Elendt M4 and Elendt M7 are high-hardness media currently recommended for Organization for Economic Cooperation and Development (OECD) testing. COMBO is a softer medium similar in total hardness to natural water found in the environment. Tier I consistent of an acclimation phase; Tier II involved a 21-day evaluation of survival, growth, and reproduction; and Tier III used each medium in a 21-day chronic study using a reference toxicant, 3,4-dichloroaniline (3,4-DCA). The evaluation of the performance of each medium was based on acceptance criteria similar to those used by the U.S. Environmental Protection Agency and the European Commission. Tests were run concurrently at three laboratories to assess interlaboratory variability. Daphnids were acclimated to the media for less than 1 month. Daphnid performance in all media exceeded the European Economic Community (EEC) validity criteria; however, reproductive performance and growth were significantly greater in the Elendt media than in COMBO. 3,4-DCA exerted more toxicity to daphnids in COMBO medium [no-observed-effect concentration (NOEC), <3.1microg/liter] compared with those in the Elendt media (NOEC,

Evaluation of a high-hardness COMBO medium and frozen algae for Daphnia magna.

A new high-hardness (H-H) COMBO medium for long-term culturing and bioassay testing of Daphnia magna was evaluated in 21-day survival, growth, and reproduction studies. The COMBO medium originally designed for softwater daphnid species (i.e., D. pulicaria) was modified for the hardwater species D. magna. This medium also allowed continuous culturing of a green algal food source for daphnids, Ankistrodesmus falcatus. After 12 generations of culturing in H-H COMBO medium, the mean fecundity was 128 +/- 12 (coefficient of variation = 9.4%). No significant observations of dead young, aborted eggs, or reduced antennas were made during the 6 months of continuous culturing. The no-observable-effect concentration (NOEC) for a reference toxicant standard, 3,4-dichloroaniline (3,4-DCA), was 8.3 micrograms/liter, which is similar to published values. These studies demonstrate that H-H COMBO is an acceptable medium for use for culturing and bioassay testing with D. magna. Additional experiments using frozen aliquots of A. falcatus were conducted. Although mean fecundity (64 +/- 7) and adult length were significantly decreased from the values for daphnids fed fresh algae, the NOEC for 3,4-DCA was > 25 micrograms/liter. The use of this alternative food source in bioassay testing appears promising, but further optimization of feeding rates is warranted.

Carcinoid tumour of the lung.

A retrospective analysis of 29 patients with carcinoid tumour of the lung treated between 1980 to 1995 is presented. There were 15 females and 14 males with a mean age of 57 years (range 28-72). Fourteen of the 29 carcinoids were peripheral and the remaining 15 were central. Preoperative histology was available in 17. Surgical resection was carried out in 27 patients, one patient was unfit whilst the other patient had multiple liver metastases at presentation. Surgical treatment offered were lobectomy (n = 19), pneumonectomy (n = 3), sleeve lobectomy (n = 3) and segmentectomy (n = 2). Twenty three patients were stage 1 tumours, 3 were stage II and one was stage III and 1 was stage IV. Postoperative histology confirmed typical carcinoids in 24 patients and the remaining 5 were atypical. There was one perioperative death from massive pulmonary embolism and there was no morbidity. Overall five year survival rate for patients with carcinoid was 96.4%. Five year survival for typical carcinoid and that of atypical carcinoid was 100% and 77.8% respectively. Typical carcinoids carry an excellent prognosis and should be offered conservative lung resection, whilst atypical carcinoids which behave aggressively should be treated by radical lung resections.

Results of surgical treatment of oesophageal cancer.

Oesophagogastrectomy is the best available treatment for patients with carcinoma of the oesophagus or cardia. A retrospective analysis of our experience with 485 patients who were treated surgically forms the basis of this report. Of the 317 patients who underwent resection (resectability rate of 65%) only 210 were considered to be potentially curative. Overall, the 5-year survival rate for oesophageal cancer was 3%, whilst curative resection had a 5-year survival rate of 22% and varied according to stages. Five-year survival rate was 67.7% for patients with Stage I disease compared with 27.6, 9.4 and 6.4% for Stages IIa, IIb and III disease respectively. There were no 5-year survivors with Stage IV disease or with those patients who underwent an incomplete resection. Curative resection carried a mortality rate of 3.8%, whereas incomplete resection or palliative procedure carried higher mortality rates of 14 and 20.7% respectively. Adequate post-operative analgesia was provided by continuous extrapleural intercostal nerve block. Morbidity, mainly caused by respiratory complications, occurred in 30 patients (6.2%), with three patients requiring ventilatory support. Outcome was influenced mostly by the extent of the disease and the completeness of surgical resection rather than by histological type. We conclude that surgical treatment provides better longevity than any other type of therapy and remains the standard against which combined modality treatment should be compared. Our experience suggests that surgical treatment can be achieved with minimal morbidity and mortality.

Results of surgical treatment of stage I and II lung cancer.

Pulmonary resection remains the most appropriate treatment for localised bronchogenic carcinoma, since prognosis and outcome are currently dependent on surgical resectability. A retrospective analysis of our experience with three hundred and thirteen stage I (n=250) and stage II (n=63) patients treated surgically form the basis of this report. The initial pulmonary resection was lobectomy in 173 patients, bilobectomy in 38, sleeve lobectomy in 12, pneumonectomy in 59, wedge excision or segmentectomy in 31. The overall operative mortality was 3.2%; 4.03% for lobectomy and 1.6% for pneumonectomy. Morbidity was observed in 21 (6.7%) patients. Four out of sixteen small cell carcinoma patients had postoperative adjuvant chemotherapy. Survival in patients with stage I tumours was 71% at 5 years and 61% at 10 years compared with 41% at 5 years and 35% at 10 years for patients with stage II disease. The five year survival after pneumonectomy was significantly (p<0.05) better for both stage I and stage II lung cancer than after lobectomy. Five year survival in stage I carcinoma was not influenced by histological type, while there was statistically significant difference (p<0.05) in survival between adenocarcinoma (0%) and squamous cell carcinoma (46%) in stage II disease. We conclude that an aggressive surgical approach can provide an excellent prognosis for recovery and long term cure in most patients with early stage lung cancer.

A prospective, randomized comparison of interpleural and paravertebral analgesia in thoracic surgery.

We have undertaken a prospective, randomized comparison of the superficially similar techniques of interpleural and paravertebral (extrapleural) analgesia in 53 patients undergoing posterolateral thoracotomy. Local anaesthetic placed anterior to the superior costotransverse ligament and posterior to the parietal pleura produces a paravertebral block and instilled between the parietal and visceral pleurae produces an interpleural block. Patients received preoperative and postoperative continuous bupivacaine paravertebral blocks in group 1 and interpleural blocks in group 2. Premedication comprised diclofenac and morphine, and after operation all patients had regular diclofenac and patient-controlled morphine (PCM). Analgesia was assessed by visual analogue pain scores (VAS), PCM requirements, ratio of preoperative to postoperative spirometric values (PFT), rates of postoperative respiratory morbidity (PORM) and hospital stay, all recorded by blinded observers. Eight patients were withdrawn and data from 45 patients were analysed. Patient characteristics, surgery, VAS scores and PCM use were similar in both groups. PFT were significantly better (P = 0.03-0.0001) in group 1, and PORM was lower and hospital stay approximately 1 day less in this group. Five patients in group 2 became temporarily confused, probably because of bupivacaine toxicity (P = 0.02). We conclude that bupivacaine deposited paravertebrally produced greater preservation of lung function and fewer side effects than bupivacaine administered interpleurally.

Results of surgical treatment of stage III lung cancer.

The role of surgery in the management of Stage III lung cancer is controversial. A retrospective analysis of our experience with 220 Stage III patients treated surgically (Stage IIIa n = 174, Stage IIIb n = 46) form the basis of this report. Of the 140 patients who underwent resection only 88 were considered to be potentially curative, all but two being operated in Stage IIIa. The overall 5-year survival rate for Stage III lung cancer was 12.1% whilst curative resection had a 5-year survival rate of 31.8%. The 5-year survival rate increased to 42% with curative resection for T3N0M0 patients. There were no 5-year survivors with incomplete resection. There were no 5-year survivors in Stage IIIb disease. Five-year survival rates for N0 (n = 62), N1 (n = 78), and N2 (n = 80) irrespective of T status were 37.2%, 3.4% and 5.6%, respectively. The operative mortality rate was only 3.4% for curative resection while palliative or non-resection patients had a mortality rate of 10.6%. Eighty-eight patients, 55 of Stage IIIa and 23 of Stage IIIb had postoperative radiotherapy with a median survival of 12 and 9 months, respectively. Fifteen small cell carcinoma patients had postoperative adjuvant chemotherapy with a median survival of 6.5 months. The only 5-year survivor in this group also had a curative resection. We conclude that metastasis to lymph nodes usually implies systemic disease and a poor prognosis. Surgical therapy continues to be the treatment of choice in a small subset of patients with Stage III resectable lung cancer discovered at thoracotomy.(ABSTRACT TRUNCATED AT 250 WORDS)

Egg size, postembryonic yolk, and survival ability.

Neonates of many species are dependent upon a post-embryonic yolk (PEY), a residual of the energy reserve of the developing embryo. Offspring hatching from large eggs have relatively more PEY than offspring from small eggs. Among daphniid Cladocera, large species produce larger eggs than smaller species. We have found that the proportional amount of energy reserve in eggs of five species of Cladocera is similar, but neonates of the larger Cladocera are born with a greater relative amount of postembryonic yolk, as triacylglycerol, than small species. Apparently, more of the reserve is metabolized by embryos of small species. This is correlated with the higher unitweight metabolic rates of smaller animals. It has been argued that animals should produce relatively larger eggs when exposed to low or unpredictable food conditions to increase the survivorship of their offspring. The physiological constraint of greater relative energy requirements of small embryos may limit PEY and explain why offspring of larger eggs survive better in low or unpredictable food resource environments.

Population oscillations and energy reserves in planktonic cladocera and their consequences to competition.

Time lags in an individual's response to decreased food densities are responsible for oscillations in laboratory populations of Daphnia galeata mendotae. Visible energy reserves of triacylglycerols accumulate in the body of animals at low population densities when food is abundant and are later metabolized at high population densities when food is scarce to temporarily sustain activity and reproduction. After these energy reserves are metabolized many individuals, primarily juveniles, starve and die. The length of the time lags is a function of the amount of energy reserve accumulated in the individual. Because this sustained activity and reproduction further decreases food concentrations to very low levels, individuals of a second smaller-body-sized species, Bosmina longirostris, that do not have sufficient energy reserves quickly starve and die. Thus the accumulation of energy reserves in individuals underlies the time lags important in causing population oscillations and has consequences to interspecific competition.

Developmental phases of the biocoenosis.

Species number and diversity increase log-linearly with time during the early development of a biocoenosis. This period may be divided into three phases. In the first phase, diversity increases with the rapid immigration of species into the newly established habitat. In the second phase, diversity increases as common species become less common and rare species less rare. This period ends with the attainment of a maximum diversity pattern. In the third phase, rare species continue to invade the habitat until it is saturated. In each phase there is a maximal number of species that can invade the habitat.