Sperm viability and sperm competition in insects.

Sperm quality plays an important role in vertebrates in determining which male has the advantage when two or more males compete to fertilize a female's ova. In insects, however, the importance of sperm quality has never been considered, despite sperm competition being widespread and well studied in this group. We tested the hypothesis that sperm viability, measured as the proportion of live sperm, covaried with the intensity of sperm competition in insects. In a pairwise comparison of seven closely related species pairs, each comprising a monandrous and a polyandrous species (i.e., with and without sperm competition, respectively), we found that in all cases the polyandrous species had a higher proportion of live sperm in their sperm stores. The distribution of the percentage of live sperm showed considerable inter- and intraspecific variation, suggesting that, all else being equal, males will vary in their ability to fertilize ova on the basis of sperm viability alone. Our results suggest that sperm viability is one of a suite of male adaptations to sperm competition in insects.

Strategic allocation of ejaculates by male Adélie penguins.

Sperm competition theory suggests that males should strategically allocate sperm to those females that will bring them the best possible genetic returns. Although males of a number of species of insects and fishes have been shown to allocate sperm strategically, we provide, to our knowledge, the first evidence that an avian species is also capable of allocating ejaculates. Male Adélie penguins (Pygoscelis adeliae) are more likely to transfer sperm during extra-pair copulations (EPCs) than during pair copulations. We investigated the question of how males allocate ejaculates within the constraints of limited sperm availability and found (i) that males that engaged in EPC attempts ejaculated less often when copulating with their social partner than males that made no EPC attempts, and (ii) that there was no difference between males that were involved in failed EPC attempts and those that were involved in successful EPCs in the proportion of copulations that resulted in sperm transfer. These results indicate that males achieve strategic allocation of sperm within the constraints of limited sperm availability by withholding ejaculates from their social partners.

Long-term colonization with single and multiple strains of Helicobacter pylori assessed by DNA fingerprinting.

The gastric pathogen Helicobacter pylori establishes long-term chronic infections that can lead to gastritis, peptic ulcers, and cancer. The species is so diverse that distinctly different strains are generally recovered from each patient. To better understand the dynamics of long-term carriage, we characterized H. pylori isolates from initial and follow-up biopsy specimens from a patient population at high risk of H. pylori infection and gastric cancer. Eighty-five isolates were obtained from 23 patients and were analyzed by genomic restriction enzyme analysis, arbitrarily primed PCR fingerprinting, (random amplified polymorphic DNA analysis), and/or restriction of specific PCR-amplified genes (restriction fragment length polymorphism analysis). A single strain was found in sequential biopsy specimens from 12 of 15 patients (80%) receiving sucralfate. In the remaining three patients treated with sucralfate, two strains were identified in two patients and three strains were identified in the third patient. In contrast, a single strain was found in sequential biopsy specimens from only three of eight patients (37%) receiving bismuth, metronidazole, and nitrofurantoin. Two strains were identified in five other patients receiving bismuth-antibiotic (63%). Immunoglobulin G antibodies to H. pylori were present in the sera of all patients. Thus, H. pylori colonization can persist for long periods (up to at least 4 years), despite high titers of immunoglobulin G antibodies in serum. Resistance to metronidazole was noted in some strains before and/or after treatment, but all strains remained susceptible to amoxicillin, tetracycline, and nitrofurantoin. We conclude that H. pylori genotypes, as measured by several sensitive DNA fingerprinting methods, can remain stable for years in vivo, despite the acquisition or loss of drug resistance, circulating antibody, or exposure to antibiotics or sucralfate.

Ascorbic acid, Helicobacter pylori and Lewis phenotype among blacks and whites in New Orleans.

Gastric juice ascorbic acid concentrations were examined in black and white patients. Significantly lower concentrations were found in blacks, in the absence of a significant difference in the plasma concentration of vitamin C between races. Blacks had higher prevalence of Helicobacter pylori infection, higher gastric pH, more severe acute and chronic inflammation of the gastric mucosa and higher frequency of Lewis (a-b-) phenotype. Although most of these factors have been related to low ascorbic acid levels in gastric juice, none of them could account entirely for the difference between races either individually or after joint consideration. These observations may help to explain the high incidence of gastric carcinoma among the black population in southern Louisiana.

Vitamin C concentration in gastric juice before and after anti-Helicobacter pylori treatment.

OBJECTIVES: To investigate the change of vitamin C concentration (ascorbic and dehydroascorbic acid) in gastric juice after anti-Helicobacter pylori treatment, and to relate any observed change to gastric pH, inflammatory compromise of the gastric mucosa, plasma vitamin C concentration, and smoking habits. METHODS: Plasma and gastric juice vitamin C, fasting gastric juice pH, gastric histology, and smoking status were studied in 70 patients with H. pylori-associated gastritis before and after therapy. RESULTS: Gastric juice ascorbic acid increased significantly after H. pylori clearance. For the most part, this change was confined to patients who experienced reduction of gastric pH. It was also related to improvement of the compromise of the gastric epithelium, reduction of the proportion of vitamin C composed by dehydroascorbic acid, and increase of the gastric juice/plasma vitamin C concentration gradient. Smokers had lower vitamin C concentrations in plasma and gastric juice before and after H. pylori clearance than nonsmokers. CONCLUSIONS: The findings are consistent with a causal association between H. pylori infection and low ascorbic acid levels in gastric juice, and support two mechanisms for this association: increased oxidation and a decreased secretion of ascorbic acid.

Helicobacter pylori-associated gastritis and the ascorbic acid concentration in gastric juice.

Patients infected with Helicobacter pylori have abnormally low ascorbic acid concentration in gastric juice. Low vitamin C intake and Helicobacter pylori infection have been related to an increased risk of gastric carcinoma. This report examines the association between ascorbic acid and Helicobacter pylori in patients referred for upper gastrointestinal endoscopy. Elevated gastric pH and the damage to the gastric surface epithelium were inversely associated with the ascorbic acid concentration in gastric juice. We postulate that these two factors mediate the ascorbic acid-decreasing effect of Helicobacter pylori. Patients with nonpremalignant conditions (normal gastric histology, diffuse antral gastritis, or duodenal ulcer) had lower gastric pH, less damage to the gastric epithelium, and higher levels of ascorbic acid in gastric juice than patients with atrophic gastritis, intestinal metaplasia, or dysplasia.

Serum pepsinogens as markers of response to therapy for Helicobacter pylori gastritis.

We have investigated the effect of therapy for Helicobacter pylori gastritis on serum concentrations of pepsinogen I and II in 43 patients. In the 22 patients in whom therapy resulted in dramatic decrease in gastritis scores and in clearance of the bacteria, there was a highly significant (P = 0.0001) fall in mean serum pepsinogen II from 13.3 +/- 0.8 to 7.9 +/- 0.7 micrograms/liter, and a less pronounced fall in pepsinogen I from 89.0 +/- 5.9 to 78.5 +/- 0.4 micrograms/liter (P = 0.01). These changes resulted in a significant (P = 0.01) increase in the pepsinogen I/II ratio. In contrast, nonsignificant declines of 3.5% and 11.6% were observed in mean pepsinogen I and II levels in the 21 patients whose gastritis failed to resolve histologically and whose infection did not clear. These findings suggest that serum pepsinogen levels, especially pepsinogen II, are a new tool that may be found to be clinically useful in evaluation of treatment outcome in patients with H. pylori-associated gastritis.

Why do females copulate repeatedly with one male?

For most animals, a small number of copulations is sufficient to fertilize all the eggs that a female will lay at any one time. However, in some species a very high frequency of mating occurs, indicating that individuals copulate many more times than are necessary for fertilization. If copulation behaviour carries costs, then the question arises as to how individuals of both sexes benefit from repeated matings with a single partner. For a male, a high frequency of copulation appears to be advantageous in securing or assuring paternity when his sperm is in competition with those of another male. Since copulation is likely to be as costly for females as it is for males, it is necessary to seek adaptive explanations from the female perspective. Attention is now being focused on why females should copulate repeatedly with a single male.

Mechanisms of sperm competition.

Sperm competition occurs when two (or more) males inseminate a single female during a reproductive cycle, but what determines which one of them will fertilize her eggs? Is it simply a lottery, or are there some more complex rules by which matings are translated into offspring? Several studies covering various animal groups have shown that mating order effects are often important in determining paternity patterns: in animals as different as insects and birds, the sperm from the last male to mate often has precedence over previously introduced sperm. Recently, behavioural ecologists and physiologists have started to examine the mechanisms by which sperm precedence is achieved. The study of sperm competition mechanisms complements the more behavioural studies, and a combination of the two approaches used on single species should prove to be particularly rewarding.

Extra-pair copulation and sperm competition in the zebra finch.

Most birds are monogamous, but recent studies have shown that extra-pair copulations (EPCs) occur frequently despite a range of paternity guards, including mate-guarding and frequent copulation. Although EPCs are known to result in extra-pair paternity, there are no previous quantitative estimates of the success of EPCs in fertilizing eggs. We present here estimates of the likelihood of success of extra-pair copulations in a monogamous passerine, the zebra finch Poephila guttata. We show that (1) EPCs occurring under semi-natural conditions in captivity result in extra-pair paternity, (2) sperm from the last male to mate has precedence over previous matings: a single EPC occurring last is disproportionately successful in fertilizing eggs, but EPCs followed by further pair copulations have a low probability of success. These results have important implications for sexual selection theory.

Nonsurgical treatment for symptomatic nonparasitic liver cyst.

Liver cysts seldom become symptomatic. For the few requiring intervention, various surgical modalities have been described. Cyst fluid has been removed by simple needle aspiration. Injection of formalin into echinococcus cysts at time of operation is not uncommon. In an analogy to the treatment of kidney cysts, we evacuated a large symptomatic liver cyst by percutaneous drainage and instilled alcohol as a sclerosing agent. This simple procedure may be sufficient treatment for selected symptomatic nonparasitic liver cysts.

Endoscopic papillotomy in Caroli's disease twenty-year follow-up of a previously reported case.

A patient diagnosed in 1963 as having congenital dilation of intrahepatic bile ducts, presented in 1982 with common bile duct lithiasis. Endoscopic papillotomy and stone extraction were followed by an unusual complication, hiccups lasting one week. We suggest that endoscopic papillotomy should be considered in selected patients with Caroli's disease. Typical and atypical features of this case presentation are discussed.

Alpha 1-antitrypsin deficiency and liver cirrhosis in adults.

Although cirrhosis of the liver caused by alpha 1-antitrypsin deficiency is not uncommon in children, only a few cases have been described in adults. We have seen three such patients--one man and two women, ranging in age from 57 to 66 years. These cases show the wide spectrum of this genetically influenced disease.

Neuropsychiatric syndromes after gastric partition.

A neuropsychiatric syndrome developed in four patients 2 1/2-9 months after gastric partition for morbid obesity. Since the partition, all four patients had recurrent severe vomiting with severe weight loss (52 to 100 lb) and they had not had vitamin supplementation. Two patients had peripheral neuropathy along with confusion and memory loss of recent events. The other two had peripheral neuropathy alone. Vitamin B complex replacement was especially helpful in the management of these patients. Peripheral neuropathy completely resolved in one of the patients, whereas the other three patients were left with residual weakness in their extremities and two had recent memory loss. Awareness of this complication may result in early recognition and treatment in the postgastric partition patient.

A comparison of bumetanide and furosemide in the treatment of ascites. Cooperative study.

In a cooperative study by clinicians in three medical facilities, bumetanide was compared with furosemide in patients presenting with ascites, a complication of chronic liver disease. In an open, parallel, randomized trial, 43 patients received bumetanide and 16 patients received furosemide. They were treated for from one to 28 weeks. Weight loss and decrease in abdominal girth following diuretic action occurred in both groups but was statistically significant only in the bumetanide treated patients. Because of the small number of patients on furosemide, valid statistical analysis could not be obtained. No evidence of hepatic encephalopathy developed during this study, and only one patient on furosemide was discontinued as a result of severe electrolyte imbalance. Differences in changes of electrolytes and uric acid ere not statistically significant in the two groups. The majority of drug-related abnormalities were the result of the pharmacologic activity of the diuretic.

Sarcoidosis of the stomach and rectum.

A patient, whose symptoms included epigastric pain, nausea and vomiting relieved with antacids but with no history of diarrhea or constipation, was found to have generalized sarcoidosis involving his lungs, liver, lymph nodes, skin, stomach and rectum. Because sarcoidosis rarely involves the gastrointestinal tract, we report this case.