Meiotic behavior and linkage relationships in the secondarily homothallic fungus Agaricus bisporus

This study followed the transmission of 64 segregating genetic markers to 52 haploid offspring, obtained from both homokaryotic and heterokaryotic meiospores, of a cross (AG 93b) of Agaricus bisporus, the commonly cultivated "button mushroom." The electrophoretic karyotypes of the AG 93b component nuclei were determined concurrently (n = 13). Eleven distinct linkage groups were identified by two-point analysis. DNA-DNA hybridization showed that nine of these corresponded to unique chromosome-sized DNAs. Two other chromosomal DNAs were marked with nonsegregating markers, including the rDNA repeat. Two remaining chromosomes remained unmarked but hybridized to repeated-sequence probes. Cross 93b had an essentially conventional meiosis in which both independent assortment and joint segregation of markers occurred, but in which crossing over was infrequent over much of the mapped genome. The 48 homokaryotic spore-offspring had overall crossover frequencies that were similar to, but possibly slightly less than, those of three homokaryon constituents of heterokaryotic spore-offspring. These daa provide support for our earlier cytogenetic model of sporogenesis in A. bisporus, that explains why heterokaryotic spore-offspring usually appear to exhibit no recombination. No evidence favoring an alternative, mitotic model of sporogenesis was found. The resulting genetic map appears to survey the genome extensively and for the first time permits localization of loci determining economically important traits in this fungal crop species. Large differences in the vigor of homokaryotic offspring were correlated with the inheritance of certain chromosome segments and were also often associated with significant departures from Mendelian segregation ratios.

An Accurate Quantum Monte Carlo Calculation of the Barrier Height for the Reaction H + H 2 → H 2 + H

An improved quantum Monte Carlo method has been used to calculate the classical barrier height for the hydrogen exchange reaction H + H(2) --> H(2) + H with accuracies greater than previously attained. The method is exact in that, except for the easily estimated Monte Carlo statistical or sampling error, it requires no mathematical approximations or physical approximations beyond those of the Schrödinger equation. The minimum in the barrier, occurring for the collinear nuclear configuration with the protons separated by 1.757 bohrs, was found to be 9.61 +/- 0.01 kilocalories per mole above H + H(2).

Circulating prostate specific antigen-positive cells correlate with metastatic prostate cancer

Analytical flow cytometry was used to study circulating prostate specific antigen (PSA)-positive cells in 40 consecutive patients with newly diagnosed, untreated prostate cancer; 25 patients (63%) had metastatic disease confirmed by a positive bone scan. Cell suspensions were prepared for each patient from both the primary tumour and peripheral blood samples. The cells were stained with a monoclonal antibody against PSA, and analysed by flow cytometry; PSA-positive cells were sorted according to their immunofluorescence and light scatter properties. The cellular deoxyribonucleic acid (DNA) content of each specimen was also analysed to establish ploidy status. PSA-positive cells were detected in the peripheral blood of 33 patients (83%). The presence of these cells in the circulation showed a higher degree of sensitivity and specificity in predicting positive bone scans than did serum PSA levels. Circulating PSA-positive cells may represent either a subpopulation of tumour cells with distinct metastatic properties or, alternatively, host immunocytes which take up PSA in an active or passive manner.

Retrospective analysis of guardians' perceptions of cognitively impaired elderly

The increased number of elderly persons who will become cognitively impaired in the near future is a cause for concern to all in the health care professions. Even though the final determination of incapacity and incompetency is a legal decision, input from health care professionals is weighed heavily by courts. Health professionals can have influence at the clinical level and also at the level of influencing social policy. Nurses rely on input from the assessments of informal caregivers. This research was conducted to determine guardians' perceptions of important criteria on the Incompetency Assessment Scale. Eleven guardians, a majority of whom were daughters of the elderly wards, perceived 9 of the 22 criteria on the IAS as important or very important to the question of incompetency. All nine criteria are found in Minnesota's statutory definition of incompetency, and also appear in the first two levels of the Maslow hierarchy of needs. Further research is recommended to develop a weighting or clustering of criteria to more accurately ascertain the way that incompetency judgments are made by guardians and other caregivers.

Postoperative retention of urine: a prospective urodynamic study

OBJECTIVE

To investigate the cause of post-operative retention of urine in elderly men.

DESIGN

Prospective study.

SETTING

Northern General Hospital, Sheffield.

PATIENTS

32 consecutive men (median age 73, range 55-85) referred to the urology department who were unable to pass urine either within 48 hours after operation and required catheterisation (23) or after removal of a catheter inserted at the initial operation (nine).

INTERVENTION

Intermittent self catheterisation.

MAIN OUTCOME MEASURES

Urological investigation by medium fill and voiding cystometry within four weeks after operation, and minimum follow up three months thereafter.

RESULTS

6 patients resumed normal voiding before urodynamic assessment, three proceeded straight to prostatectomy, and one was unfit for self catheterisation. Of 22 men who underwent urodynamic investigation, only five had bladder outflow obstruction, who subsequently had successful prostatectomy; 15 showed either a low pressure-low flow system (seven) or complete detrusor failure (eight) and two showed pelvic parasympathetic nerve damage. With intermittent self catheterisation spontaneous voiding returned in all but one man within a median of 8 weeks (range 6-32 weeks). Recovery of bladder function took significantly longer in men with detrusor failure than in those with an underactive bladder (median 10 weeks (range 6-32 weeks) v median 8 weeks (range 6-8 weeks); p = 0.05). Three months later all patients had re-established their own normal voiding pattern with minimal residual urine on ultrasonography and satisfactory flow rates.

CONCLUSIONS

Postoperative urinary retention in elderly men is not an indication for prostatectomy; a normal pattern of micturition can be re-established by intermittent self catheterisation in most men.

Mitochondrial genetics in a natural population of the plant pathogen armillaria

Transmission and propagation of mitochondrial genotypes in fungi have not been previously investigated in the field. This study examined the distribution of nuclear and mitochondrial genotypes in a natural, local population of the fungal (Basidiomycetes) root-rot pathogen, Armillaria. Six vegetative clones, ranging in size up to 635 m, were identified on the basis of mating-type alleles. Mitochondrial DNA (mtDNA) restriction fragment patterns indicated that each vegetative clone has one, unique mtDNA type. However, as in other basidiomycetous fungi, biparental transmission of mitochondria following laboratory matings of sexually compatible haploid isolates of Armillaria resulted in a uniformly diploid mycelium that was a mosaic for both parental mitochondrial types. Therefore, either matings between monosporous, haploid isolates are uncommon in nature, or when mating does occur, cytoplasmic markers of one partner predominate during subsequent vegetative growth.

Isolation of chloroplastic phosphoglycerate kinase : kinetics of the two-enzyme phosphoglycerate kinase/glyceraldehyde-3-phosphate dehydrogenase couple

We report here a method for the isolation of high specific activity phosphoglycerate kinase (EC 2.7.2.3) from chloroplasts. The enzyme has been purified over 200-fold from pea (Pisum sativum L.) stromal extracts to apparent homogeneity with 23% recovery. Negative cooperativity is observed with the two enzyme phosphoglycerate kinase/glyceraldehyde-3-P dehydrogenase (EC 1.2.1.13) couple restored from the purified enzymes when NADPH is the reducing pyridine nucleotide, consistent with earlier results obtained with crude chloroplastic extracts (J Macioszek, LE Anderson [1987] Biochim Biophys Acta 892: 185-190). Michaelis Menten kinetics are observed when 3-phosphoglycerate is held constant and phosphoglycerate kinase is varied, which suggests that phosphoglycerate kinase-bound 1,3-bisphosphoglycerate may be the preferred substrate for glyceraldehyde-3-P dehydrogenase in the chloroplast.

The Irving sterilization technique: a report of a failure

The Irving sterilization technique is a very reliable method of surgical contraception, with only two prior mentions of failure in the literature. We present the third case of failure of an Irving operation. A discussion on the surgical aspects of the Irving technique is also presented.

Inheritance of restriction fragment length polymorphisms in Agaricus brunnescens

The cultivated mushroom, Agaricus brunnescens, is secondarily homothallic; most basidia produce only two basidiospores, each of which receives two of the four post meiotic nuclei. The segregation of restriction fragment length polymorphisms (RFLPs) detected by four plasmid probes carrying single-copy nuclear DNA of Agaricus was followed in seven parental strains including commercial, wild-collected, and artificially synthesized heterokaryons. Of a total of 367 single-spore progeny examined, 351 (95.6%) were heteroallelic at all RFLP loci heteroallelic in the respective parents. Of the 16 segregant isolates, ten (2.7% of the total) were homoallelic at all segregating loci assayed, suggesting that these isolates were most probably derived from rare spores that had received only a single postmeiotic nucleus. Some of these ten isolates had recombinant genotypes. Only five isolates (1.4% of the total) showed homoallelism at one of the loci heteroallelic in the parent, while remaining heteroallelic at other loci. These five genotypes suggest that a crossover had occurred between a marker locus and its respective centromere. Taken together, the results suggest that meiosis in A. brunnescens is accompanied by low levels of recombination and that nonsister nuclei are preferentially incorporated into basidiospores after meiosis II.

The enigma of interstitial cystitis--an autoimmune disease?

Interstitial cystitis (IC) is characterised by recurrent inflammation and destruction of bladder tissue without obvious cause. To determine whether this self-perpetuating disease is the result of an autoimmune disorder, we studied 26 patients with IC of mean duration 5 years and compared the results with those of a control group of similar age and sex with other urological complaints. We performed a standard autoimmune profile and looked for specific antibodies to normal human bladder in the serum, using an indirect immunofluorescence technique. Deep bladder biopsies were examined by conventional histology and cryostat sections were studied with peroxidase-conjugated anti-human antibodies in a search for immunoglobulin deposition within the bladder. Seventeen of 26 patients with IC (65%) and 5 of 14 controls (36%) demonstrated non-organ-specific antibodies; 40% of those with IC had anti-nuclear antibodies; 18 IC patients (75%) and 4 of 10 controls (40%) had anti-bladder antibodies present in the serum, but 5 healthy volunteers showed no such antibody activity. There was no statistically significant difference between the two groups for either type of antibody (Fisher's exact test). Only 5 of 17 patients with IC (29%) showed immunoglobulin deposition in the bladder epithelium, a similar proportion to controls (38%); 4 of these 5 had circulating anti-bladder antibodies present in the serum. Although IC patients demonstrated a non-specific increase in antibody formation, this was not significantly different from a similar group of other urological patients. The lack of specificity makes this immunological response more likely to be a secondary phenomenon associated with inflammatory damage to the bladder rather than the primary cause of the disease.

Testicular torsion in Bristol: a 25-year review

To identify changes in incidence, presentation, management and outcome, 670 patients with torsion of the spermatic cord presenting in Bristol between 1960 and 1984 have been reviewed. Among the susceptible population of 150,000, the annual incidence of torsion has increased fourfold from 11.2 cases between 1960 and 1964 to 42.8 cases between 1980 and 1984. Throughout this period greater than 90 per cent of patients have been managed by general surgeons. Patients aged between 12-18 years comprised 62 per cent but 20 per cent were 21 years or older. Torsion was commoner in the cold months, 24 per cent of cases occurring during December and January (chi 2 = 30.26, P less than 0.01). When acute torsion was relieved within 12 h of the onset of symptoms only 4 per cent of affected testes were considered non-viable, but beyond this time 75 per cent of patients received orchidectomy. Overall, 238 of 624 (38 per cent) acutely twisted testes were found to be infarcted at operation, and a further 35 patients (6 per cent) had marked testicular atrophy on review 3 months later. The testicular salvage rate has steadily improved from 45 per cent in the years 1960-64 to 67 per cent in 1980-84. Much of the increased incidence of testicular torsion is likely to reflect a greater awareness of the condition by general practitioners. It has been more than matched by an improvement in testicular salvage rate because of earlier referral.

Crosses among Homokaryons from Commercial and Wild-Collected Strains of the Mushroom Agaricus brunnescens (= A. bisporus )

A new technique for the production of hybrid strains of the cultivated mushroom Agaricus brunnescens is described. Homokaryons were recovered from regenerated protoplasts obtained from several heterokaryotic strains. A total of 16 novel hybrids were produced in 63 attempted crosses between paired homokaryons. Recovery of both homokaryons and hybrids was verified by analysis of restriction fragment length polymorphisms. Three of four hybrids fruited in small-scale tests, further confirming that the isolates were true hybrids. Colony morphology alone was found to be a poor indicator of hybrid status. In two instances, three homokaryons crossed successfully in all combinations, suggesting that there are at least three alleles at the putative mating-type locus. Crosses between homokaryons from commercial and wild-collected isolates indicated that these strains belong to the same biological species.

Nuclear migration and mitochondrial inheritance in the mushroom agaricus bitorquis

Mitochondrial (mt) DNA restriction fragment length polymorphisms (RFLPs) were used as genetic markers for following mitochondrial inheritance in the mushroom Agaricus bitorquis. In many basidiomycetes, bilateral nuclear migration between paired homokaryotic mycelia gives rise to two discrete dikaryons which have identical nuclei but different cytoplasms. Although nuclear migration is rare in A. bitorquis, unidirectional nuclear migration occurred when a nuclear donating strain (8-1), was paired with a nuclear recipient strain (34-2). The dikaryon recovered over the nuclear recipient mate (Dik D) contained nuclei from both parents but only mitochondria from the recipient mate; thus nuclei of 8-1, but not mitochondria, migrated through the resident hyphae of 34-2 following hyphal anastomosis. The two mitochondrial types present in a dikaryon recovered at the junction of the two cultures (Dik A) segregated during vegetative growth. Dikaryotic cells having the 34-2 mitochondrial type grew faster than cells with the 8-1 mitochondrial type. Fruitbodies, derived from a mixed population of cells having the same nuclear components but different cytoplasms, were chimeric for mitochondrial type. The transmission of mitochondria was biased in favor of the 8-1 type in the spore progeny of the chimeric fruitbody. Protoplasts of dikaryon (Dik D), which contained both nuclear types but only the 34-2 mitochondrial type, were regenerated and homokaryons containing the 8-1 nuclear type and the 34-2 mitochondrial type were recovered.

Fulminant ulcerative colitis in late pregnancy and the puerperium

Four patients underwent emergency colectomy during pregnancy or the puerperium for complications of ulcerative proctocolitis. Three had inactive colitis at conception, while in the fourth the disease started during pregnancy. Three patients required subtotal colectomy and ileostomy for toxic dilatation during the third trimester or within 5 days of delivery, and the fourth underwent proctocolectomy postpartum for intractable colitis. There were no maternal deaths but 2 of 4 infants died. One child weighing 1.4 kg survived vaginal delivery during the 33rd week of pregnancy, 2 weeks after his mother had undergone emergency colectomy.

A leg positioning and holding mechanism for use during knee surgery

The paper describes a novel leg positioning and support mechanism for use during knee surgery. The limb is positioned by controlling hip flexion–extension and hip abduction–adduction, using the normal thigh tourniquet as an attachment point for the mechanism. The knee joint and the lower leg are not impeded by the device and the surgeon may freely test knee joint movements.

Early experience in the operating theatre indicates significant advantages in freeing the assistant surgeon for other duties, reduced physical effort, and firmer retention of the leg. The use of the leg positioning and support mechanism may permit ergonomically improved operating techniques to be developed.

Restriction fragment length polymorphisms in the mushrooms Agaricus brunnescens and Agaricus bitorquis

Two Agaricus species, A. brunnescens (a commercial mushroom) and A. bitorquis (a wild, edible species), were examined for restriction fragment length polymorphisms. EcoRI-digested nuclear DNA from isolates of both species were cloned in plasmid vector pUC18. Ten random recombinant clones were used in Southern DNA-DNA hybridizations to probe EcoRI-digested DNA from 11 A. brunnescens isolates (7 commercial, 2 wild type, and 2 homokaryotic) and 7 A. bitorquis isolates. Most cloned fragments were polymorphic in both species. There were fewer different genotypes than expected, however, in the sample of commercial A. brunnescens strains. DNA from homokaryotic strains showed fewer bands in most hybridizations than DNA from heterokaryotic strains. All A. bitorquis isolates could be distinguished from each other as well as from every A. brunnescens strain. Putative homokaryons were detected by the loss of polymorphic bands among protoplast regenerates from one commercial strain and two strains collected in the wild.

Fine-needle aspiration biopsy and the diagnosis of thyroid cancer

Conventional criteria for the evaluation of thyroid nodules are inaccurate in identifying the small proportion of malignant neoplasms. The diagnostic accuracy of fine-needle aspiration biopsy (FNAB) for cytology was therefore assessed in 562 patients with nodular thyroid disease, 373 of whom (66.4 per cent) had histological confirmation of the cytological diagnosis. Sixty-one aspiration biopsies were positive for malignancy, and the diagnosis was confirmed histologically in 59 of these (96.7 per cent). Thus, there were two false positive cytology results among 310 patients with proven benign disease (0.6 per cent). Four of sixty-three patients with proven carcinoma had a benign cytological diagnosis, a false negative rate of 6.3 per cent. In 57 of the 59 malignancies (96.6 per cent) correctly diagnosed by FNAB the histological type of tumour was successfully identified. Overall 367 of 373 patients received correct cytological discrimination between benign and malignant nodules, an overall accuracy of 98.4 per cent for FNAB. The sensitivity of the test was 93.7 per cent and the specificity 99.4 per cent. Besides being safe, cost-effective and reliable, FNAB directs the appropriate selection of patients for surgery and enables the correct operation to be performed for each type of tumour.