Age and growth of round goby Neogobius melanostomus associated with depth and habitat in the western basin of Lake Erie.

Round goby Neogobius melanostomus were examined from the Bass Islands area in the western basin of Lake Erie, U.S.A., to determine age and growth correlations. A total of 188 specimens were collected and examined during summer 2011 with 90 aged using scale analysis. Fish were grouped by sex, depth of habitat and habitat type (anthropogenically modified shallows, natural shallows and open lake deep water). Fish ranged from 17 to 117 mm total length (LT ) and 0+ to 3+ years. Males dominated the population (1·94:1) and backcalculated age showed that both sexes grew exponentially, with male growth rate increasing faster than female. Males were significantly larger than females in LT and mass (both P < 0·001). The relative mass index (Wr ) was low for the sampled population (mean ± s.d. = 32·00 ± 26·87 g), implying that the health of the Bass Island area population is very poor when compared with the species throughout its range. This could be due to a lack of food resources related to population size or that the fish is not optimally utilizing the available food resources. In contradiction to these findings, regression slope coefficient (b), calculated using Fulton's condition factor (K) (mean ± s.d. =1·50 ± 0·20), was very low for each habitat, implying a healthy population throughout. This seemingly opposite effect may be due to more individuals per unit area in shallow waters, which would cause increased competition for resources. Poor condition may indicate that the Lake Erie population has reached saturation or may reflect indirect fitness costs associated with increasing anoxic or hypoxic hypolimnion conditions.

Proteoglycan and glycosaminoglycan synthesis in embryonic mouse salivary glands: effects of beta-D-xyloside, an inhibitor of branching morphogenesis.

The proteoglycans and glycosaminoglycans synthesized by embryonic mouse salivary glands during normal morphogenesis and in the presence of beta-xyloside, an inhibitor of branching morphogenesis, have been partially characterized. Control and rho-nitrophenyl-beta-D-xyloside-treated salivary rudiments synthesize proteoglycans that are qualitatively similar, based on mobility on Sepharose CL-4B under dissociative conditions and glycosaminoglycan composition. However, beta-xyloside inhibits total proteoglycan-associated glycosaminoglycan synthesis by 50%, and also stimulates synthesis of large amounts of free chondroitin (dermatan) sulfate. This free glycosaminoglycan accounts for the threefold stimulation of total glycosaminoglycan synthesis in beta-xyloside-treated cultures. Several observations suggest that the disruption of proteoglycan synthesis rather than the presence of large amounts of free glycosaminoglycan is responsible for the inhibition of branching morphogenesis. (a) We have been unable to inhibit branching activity by adding large amounts of chondroitin (dermatan) sulfate, extracted from beta-xyloside-treated cultures, to the medium of salivary rudiments undergoing morphogenesis. (b) In the range of 0.1-0.4 mM beta-xyloside, the dose-dependent inhibition of branching morphogenesis is directly correlated with the inhibition of proteoglycan synthesis. The stimulation of free glycosaminoglycan synthesis is independent of dose in this range, since stimulation is maximal even at the lowest concentration used, 0.1 mM. The data strongly suggest that the inhibition of branching morphogenesis is caused by the disruption of proteoglycan synthesis in beta-xyloside-treated salivary glands.

Tissue-specific expression of novel messenger ribonucleic acids cloned from a renin-expressing kidney tumor cell line (As4.1).

As4.1 cells are derived from a renin-expressing kidney tumor induced by tissue-specific oncogene-mediated tumorigenesis in transgenic mice. These cells express high levels of renin messenger RNA (mRNA) and synthesize prorenin and renin; they were therefore used as a model to further investigate the molecular biology of renin-producing kidney cells by cloning and characterizing novel mRNAs expressed in these cells. One clone, designated 1.5, was randomly selected from an As4.1 complementary DNA (cDNA) library, and two other cDNA clones, designated 4.9 and 6.9, were obtained by screening the cDNA library using a strategy to identify As4.1 cell-specific mRNAs. Each clone exhibited a highly restricted tissue-specific expression profile, including high level expression in As4.1 cells and low level expression in kidney. No homology was found between the sequence of the partial 1.5 and 4.9 cDNAs and sequences in Genbank. Southern blot analysis revealed that clone 4.9 is encoded by a single copy gene containing at least two separate exons. A homology search of the sequence of clone 6.9 revealed it to encode a cDNA to serum amyloid A protein; consistent with this identification, expression of 6.9 mRNA was highly induced in both kidney and liver after treatment of mice with Escherichia coli lipopolysaccharide.

Genetics of Coxiella burnetii.

Those organisms considered to be obligate intracellular bacteria are interesting objects for genetic studies. Little is known about their mechanisms for natural genetic exchange. Many genes from the bacterium Coxiella burnetii, an obligate intraphagolysosomal pathogen, have therefore been cloned and characterized using the heterologous host Escherichia coli. Recently, use of electroporation methodology followed by long-term selection periods have provided initial data on genetic transformation in C. burnetii.

Expression of beta-lactamase in Coxiella burnetii transformants.

Coxiella burnetii can be transformed to ampicillin resistance by electroporation with plasmids encoding beta-lactamase. However, non-plasmid emergence of resistance to ampicillin also develops. To validate the usefulness of the bla gene marker for selection and detection, transformed C. burnetii were examined for beta-lactamase expression by use of immunoblotting after SDS-PAGE. The 29-kDa mature form of the beta-lactamase protein was detected in C. burnetii lysates. Quantitation of these immunoblot signals showed that C. burnetii surprisingly expressed low levels of beta-lactamase. The results validate the use of plasmid-encoded ampicillin resistance as a means for selecting C. burnetii transformants; they also suggest that levels of ampicillin used for selection pressure should be empirically determined and that detection of beta-lactamase by antibody blotting done to confirm transformants.

A growth study of Coxiella burnetii Nine Mile Phase I and Phase II in fibroblasts.

Coxiella burnetii, a slow-growing, gram-negative, obligate intracellular bacterium, is the causative agent of Q fever in humans. The avirulent Phase II C. burnetii Nine Mile strain can invade and establish persistent infections in a wide variety of laboratory cell lines, and is generally considered to be easier to grow in culture than the wild-type Phase I organism. Efforts to improve Phase I organism yield in the BHK-21 cell line demonstrated that high CO2 conditions and the use of Dulbecco's modified Eagle's medium (DMEM) with 4.5 g/l glucose supplementation resulted in higher organism yields. Phase II organisms grown in the same cell line and conditions showed lower growth rates. Analysis revealed that increased average numbers of C. burnetii Phase I organisms within fibroblasts was due to higher growth rates within the hosts rather than to increased uptake or to increased cell-to-cell spreading. Addition of the nucleoside cytidine to the growth medium stimulated growth of Phase II but not Phase I organisms.

Electron microscopy of Coxiella burnetii in tissue culture. Induction of cell types as products of developmental cycle.

An in vitro ultrastructural study was carried out on tissue cultures (J774, murine macrophage-like tumour cell line, and BHK-21, baby hamster kidney cell line) persistently infected with C. burnetii to investigate whether the events of cellular differentiation could be visualized. At a given stage of the developmental cycle, a proportion of the cells within the affected phagolysosomes clearly underwent cellular differentiation. The cells initially showed asymmetrical septation, the primary stage of cellular differentiation, and ended with the formation of the differentiated product, a precursor to the small cell. The results verified our initial observation that the events occurring during growth in a phagolysosome represent stages of a complex developmental cycle consisting not only of i) vegetative growth by typical transverse binary fission, but also ii) cellular differentiation.

Restrictive covenants.

Sales of medical practices and physician employment contracts may contain covenants not to compete, also known as restrictive covenants. These covenants prohibit sellers from competing with buyers and employees from competing with former employers for a specified period of time. As a result of a call for legislative action to dispel confusion created by case law regarding these covenants, there now exists a statute dealing with restrictive covenants. This new law abolishes the "common calling" test, a standard for determining the enforceability of covenants not to compete in employment agreements, which the Texas Supreme Court adopted in 1987. Among other remedies, the new law provides procedures for reforming a broad restrictive covenant to one that is reasonable. This article discusses the 1987 Texas Supreme Court case and reviews the new statute.

Employment law primer.

All physicians regardless of their practice size will find themselves one day in the uncomfortable situation of dismissing an employee who may threaten legal action because of termination. Knowledge of and adherence to the basics of employment law as outlined in this article may not stop an angry dismissed employee from pursuing legal action. However, it should allow the physician to feel somewhat secure that such action likely will not be successful.

Blood transfusions and Jehovah's Witnesses.

Jehovah's Witnesses believe that a human must not sustain his life with another creature's blood, and they recognize no distinction "between taking blood into the mouth and taking it into the blood vessels." It is their deep-seated religious conviction that Jehovah will turn his back on anyone who receives blood transfusions (1). Thus, Jehovah's Witnesses regularly refuse transfusions for themselves and their children because they believe the procedure creates a risk of losing eternal salvation. Legally, such refusals are based on the constitutional grounds that the transfusion is an invasion of the right of privacy and a violation of the individual's freedom of religious practice. When courts review these refusals they focus on state interests that outweigh the individual's rights. With an eye toward providing guidance to Texas physicians in dealing with such refusals, this article reviews case law on the subject of blood transfusions and Jehovah's Witnesses.

Consent requirements for treatment of minors.

The American Academy of Family Physicians, the American Academy of Pediatrics, the American College of Obstetricians and Gynecologists, the Nurses Association of the American College of Obstetricians and Gynecologists, and the National Medical Association recently released guidelines aimed at protecting the privacy of adolescent patients. The organizations stated that, in many cases, young people will not confide in health professionals if the young people feel that these discussions will be reported to their parents. Ultimately, the organizations said, health risks to adolescents are so impelling that legal barriers and deference to parental involvement should not stand in the way of needed health care. In Texas there is a statute regarding consent for medical treatment of minors, which responds to the above organizations' concerns about confidentially treating children for substance abuse, sexually transmitted diseases, and suicide prevention. However, the statute is silent in regard to medical treatment involving prescription contraceptives. By negative inference, the statute would preclude a minor on her own from making a decision about abortion. This article examines Texas statutes dealing with consent for medical treatment for minors and discusses US Supreme Court decisions on a minor's rights to abortions and contraceptives.

PIP: Texas State law concerning consent requirements for medical treatment of minors is reviewed, both explicit statutes and inferred situations, specifically prescription contraception and abortion. Parental consent is defined as consent of only 1 parent or the parent with custody during the week (sole managing conservator), or the possessory conservator in emergencies. When the parent cannot be contacted, a grandparent, adult sibling, aunt or uncle, education institution, adult with written authorization to consent, court, or the Texas Youth Commission, may consent. Minors may give consent if they are in the military, at least 16 years old and emancipated, or if the consent is for diagnosis and treatment of a reportable disease, sexually transmitted disease, for treatment (other than abortion) of pregnancy, suicide prevention or chemical addiction. The consequences of the Roe v Wade decision are summarized. This decision implies that in Texas a physician who performs and abortion on an unemancipated minor who is mature and informed will probably not be held liable for civil damages to the minor's parents, unless the court decides that she is not mature and well informed. In Carey v Population Services International, the Supreme Court struck down a New York statute that made sale of nonprescription contraceptives to a minor criminal. By extension, since a minor can probably consent to abortion, Texas physicians should be able to prescribe contraceptives to a mature and well informed minor. The privacy and physician-patient relationship of the minor should be protected in such situation.

Concurrent care coverage by Medicare.

Medicare is a Federal Health Insurance Program administered by the Health Care Financing Administration for the elderly and certain disabled persons. The Texas Medicare carrier disseminates information and develops educational programs for improved understanding. "Concurrent care" exists when services are performed by more than one physician during a period of time for the same patient. Since Medicare does not have specialty designations for endocrinology, oncology, rheumatology, hematology, and infectious disease physicians, an X6 modifier is used for recognition. Services by two physicians of the same specialty or subspecialty rarely warrant coverage, but services by one physician and later care by another physician for an acute episode do warrant coverage. Emergency department codes should be used when care is given in that department and appropriate modifiers should be used by second- and third-opinion consultants in order to avoid the appearance of concurrent care. Diagnosis related to specialty and documentation of acute situations help avoid denial for "not reasonable or necessary" services. Physicians should use the "Waiver of Liability" when concurrent care seems necessary but is not likely to be covered by Medicare.

Directors' and officers' liability.

Charities or business associations frequently ask physicians--due to their status in the community--to serve as directors or officers. Just as frequently, physicians agree to serve in those positions without fully understanding the responsibilities and possible liabilities they are assuming. This article describes the duties of directors and officers and the liabilities associated with the job.

From informed consent to informed refusal.

This article traces the development of the informed consent concept, focusing on Texas case law and statutory provisions. We describe the proper use of the Texas Medical Disclosure Panel forms in establishing informed consent and illustrate common problems in proving that informed consent has been obtained. The need for effective physician-patient dialogue and communication is discussed.