Population demographics of American eels Anguilla rostrata in two Arkansas, U.S.A., catchments that drain into the Gulf of Mexico.

The goal of this study was to compare American eel Anguilla rostrata life history in two inland river systems in Arkansas, U.S.A., that ultimately discharge into the Gulf of Mexico via the Mississippi River and the Red-Atchafalaya catchments. From 21 June 2011 to 24 April 2014, 238 yellow-phase A. rostrata were captured in the middle Ouachita River and tributaries using boat electrofishing and 39 in the lower White River using multiple sampling gears. Most of them were caught downstream of dams in both basins (61%). Medium-sized A. rostrata ranging from 225 to 350 mm total length (LT ) were the most abundant size group in the Ouachita River basin, but they were absent from the White River. Mean LT at age 4 years (i.e. youngest shared age) was 150 mm greater for the White River than the Ouachita River basin. Anguilla rostrata appeared to have a greater initial LT (i.e. minimum size upon arrival) in the White River that allowed them to reach a gonado-somatic index (IG ) of 1·5 up to 4 years earlier, and downstream migration appeared to occur 5 years earlier at 100 mm greater LT ; these differences may be related to increased river fragmentation by dams in the Ouachita River basin. Growth and maturation of A. rostrata in this study were more similar to southern populations along the Atlantic coast than other inland populations. Adult swimbladder nematodes Anguillicoloides crassus were not present in any of the 214 swimbladders inspected. Gulf of Mexico catchments may be valuable production areas for A. rostrata and data from these systems should be considered as range-wide protection and management plans are being developed.

Expression analysis of human pterygium shows a predominance of conjunctival and limbal markers and genes associated with cell migration.

PURPOSE: Pterygium is a vision-impairing fibrovascular lesion that grows across the corneal surface and is associated with sunlight exposure. To increase our understanding of the cells types involved in pterygium, we have used expressed sequence tag analysis to examine the transcriptional repertoire of isolated pterygium and to identify marker genes for tissue origin and cell migration. METHODS: An unnormalized unamplified cDNA library was prepared from 15 pooled specimens of surgically removed pterygia as part of the NEIBank project. Gene expression patterns were compared with existing data for human cornea, limbus, and conjunctiva, and expression of selected genes was verified by immunofluorescence localization in normal eye ocular surface and in pterygium. RESULTS: Sequence analysis of 2,976 randomly selected clones produced over 1,800 unique clusters, potentially representing single genes. The most abundant complementary DNAs from pterygium include clusterin, keratins 13 (Krt13) and 4 (Krt4), S100A9/calgranulin B, and spermidine/spermine N1-acetyltransferase (SAT1). Markers for both conjunctiva (such as keratin 13/4 and AQP3) and corneal epithelium (such as keratin 12/3 and AQP5) were present. Immunofluorescence of Krt12 and 13 in the normal ocular surface showed specificity of Krt12 in cornea and Krt13 in conjunctival and limbal epithelia, with a fairly sharp boundary at the limbal-corneal border. In the pterygium there was a patchy distribution of both Krt12 and 13 up to a normal corneal epithelial region specific for Krt12. Immunoglobulins were also among the prominently expressed transcripts. Several of the genes expressed most abundantly in excised pterygium, particularly S100A9 and SAT1, have roles in cell migration. SAT1 exerts its effects through control of polyamine levels. IPENSpm, a polyamine analogue, showed a significant ability to reduce migration in primary cultures of pterygium. A number of genes highly expressed in cornea were not found in pterygium (several small leucine-rich proteoglycan family members) or were expressed at considerably lower levels (ALDH3A1 and decorin). CONCLUSIONS: The expression pattern of keratins and other markers in pterygium most closely resemble those of conjunctival and limbal cells; some corneal markers are present, notably Krt12, but at lower levels than equivalent conjunctival markers. Our data are consistent with the model of pterygium developing from the migration of conjunctival- and limbal-like cells into corneal epithelium. Identification of genes with roles in cell migration suggests potential therapeutic targets. In particular, the ability of polyamine analogues to reduce migration in primary cultures of pterygium presents a possible approach to slowing pterygium growth.

Intratracheal administration of perfluorochemical-gentamicin suspension: a comparison to intravenous administration in normal and injured lungs.

Respiratory infections can lead to acute lung injury and perfusion abnormalities. We hypothesized that intratracheal (IT) administration of a perfluorochemical (PFC) gentamicin (G) suspension as compared to intravenous (IV) administration of gentamicin will result in higher lung tissue levels of gentamicin, while maintaining safe serum levels. To test this hypothesis, 21 lambs with normal and acid injured lungs were studied for 4 hr, using 2 different drug delivery methods, IT and IV. Lungs were injured with warm HCl acid in saline lavage, followed by partial liquid ventilation with perflubron (bolus FRC = 20 mL/kg). G at a dose of 5 mg/kg was delivered either IT (G-PFC; 20 mL/kg) or IV (aqueous injection with IT 20 mL/kg PFC alone). Throughout the study, serum G levels, arterial blood gases, respiratory system compliance, and mean arterial blood pressure were measured. Lung tissue G levels were measured at 4 hr and averaged across lobes. Physiologic gas exchange and pulmonary function were maintained throughout the protocol for both the normal and injured lungs. Intravenously administered G resulted in an initial 5-min serum concentration of 43 +/- 2.5 mcg/mL, followed by an exponential decline over the 4-hr protocol to a level of 2.1 +/- 0.23 mcg/mL at hr 4. The intratracheally administered G suspension resulted in a 5-min serum concentration of 1.8 +/- 0.98 mcg/mL and remained relatively constant throughout the protocol, with a 4-hr level of 1.6 +/- 0.29 mcg/mL. With respect to lung tissue G levels, IT administration was significantly more effective in delivering the drug to the normal lungs than IV (31.4 +/- 3.3 mcg/g vs. 4.0 +/- 0.7 mcg/g) 4 hr after administration. In the lung injury group, there was a small but significant difference in lung tissue G levels, with the IT-administered perfluorochemical-G suspension achieving greater levels than the IV-administered G (11.9 +/- 0.52 mcg/g vs. 10.1 +/- 0.8 mcg/g). Additionally, the drug delivered IV and IT in both the normal and injured lung models was homogeneously distributed throughout the lung. These data show that G lung tissue levels in both normal and injured lungs were higher in the IT group when compared to IV administration. The results of this study demonstrate that in normal and injured lungs, homogeneous G lung tissue levels can be more effectively achieved at lower serum levels when delivered IT in a G-PFC suspension as compared to IV administration.

Intra-tracheal delivery strategy of gentamicin with partial liquid ventilation.

Patients with pulmonary infection often present with ventilation and perfusion abnormalities, which can impair intravenous antibiotic therapy. Intra-tracheal (i.t.) administration has met with obstacles, such as inadequate delivery to affected lung regions and the disruption of gas exchange. We hypothesized that i.t. administration of a gentamicin (G)/perfluorochemical (PFC) suspension (G/PFC) would effectively deliver and distribute gentamicin to the lung, while maintaining gas exchange and non-toxic serum levels. In addition, we sought to compare serum G and lung levels and distribution of G when G/PFC is administered at the initiation of partial liquid ventilation (PLV) vs. during PLV. To test this hypothesis, 17 newborn lambs were ventilated by PLV with perflubron (LiquiVent) for 4 h using three different G (5 mg kg-1) administration techniques: i.t. slow-fill (SF) (n = 6; G/PFC over 15 min at start of PLV), i.t. top-fill (TF) (n = 6; G/PFC 10-65 min after start of PLV), intravenous (i.v.) (n = 5, aqueous injection at start of PLV). Serum levels of gentamicin were obtained 1, 15, 30 and 60 min after administration, and hourly there after for the remainder of the protocol (4 h). Arterial blood gas and pulmonary function measurements were obtained throughout the protocol. At the conclusion of the protocol, representative samples from each lung lobe, the brain and kidney were homogenized and assayed for gentamicin. All results are presented as the mean +/- SEM; P < 0.05. Over time, serum gentamicin levels were greatest (P < 0.05) in i.v. (11.0 +/- 2.3 micrograms ml-1), followed by TF (2.3 +/- 0.1 micrograms ml-1) and SF (0.8 +/- 0.1 microgram ml-1). The percentage of the administered dose remaining in the lungs after 4 h was greater (P < 0.05) following i.t. delivery (SF 23.8 +/- 4.3%, TF 13.7 +/- 2.5%) as compared to i.v. (3.7 +/- 0.5%). These findings suggest that for a given dose of G, both SF and TF delivery methods of G/PFC can enhance pulmonary, relative to systemic, antibiotic coverage.

Fusion of green fluorescent protein with the Zeocin-resistance marker allows visual screening and drug selection of transfected eukaryotic cells.

Green fluorescent protein (GFP) and the Zeocin-resistance gene Sh ble (ZeoR) were fused together to generate a bifunctional protein for the identification and selection of transfected mammalian cells. Expression of this hybrid selectable marker, GFP-ZeoR, was visually detected and conferred Zeocin resistance in prokaryotes and eukaryotes. This selectable marker provides a way to determine transient transfection efficiencies in tissue culture cells using fluorescence microscopy. Expression of the GFP-ZeoR was also used to identify and select stable mammalian cell lines expressing a heterologous gene. Selection was efficient and GFP fluorescence provides an excellent, noninvasive technique to monitor the success of Zeocin selection during the development of the stable cell lines. This hybrid resistance gene combines the functional properties of the Zeocin-resistance marker and GFP and should be useful for combined selection and fluorescence in a variety of organisms.

Comparison of perfluorochemical fluids used for liquid ventilation: effect of endotracheal tube flow resistance.

Neonatal endotracheal tubes with small inner diameters are associated with increased resistance regardless of the medium used for assisted ventilation. During liquid ventilation (LV) reduced interfacial tension and pressure drop along the airways result in lower alveolar inflation pressure compared with gas ventilation (GV). This is possible by optimizing liquid ventilation strategies to overcome the resistive forces associated with liquid density (rho) and viscosity (mu) of these fluids. Knowledge of the effect of rho, mu, and endotracheal tube (ETT) size on resistance is essential to optimize LV strategies. To evaluate these physical properties, three perfluorochemical (PFC) fluids with a range of kinematic viscosities (FC-75 = 0.82, LiquiVent = 1.10, APF-140 = 2.90) and four different neonatal ETT tubes (Mallincrokdt Hi-Lo Jet ID 2.5, 3.0, 3.5, and 4.0 mm) were studied. Under steady-state flow, flow and pressure drop across the ETTs were measured simultaneously. Resistance was calculated by dividing pressure drop by flow, and both pressure-flow and resistance-flow relationships were plotted. Also, pressure drop and resistance were each plotted as a function of kinematic viscosity at flows of 0.01 L.s-1 for all four ETT sizes. Data demonstrated a quadratic relationship with respect to pressure drop versus flow, and a linear relationship with resistance versus flow: both were significantly correlated (R = 0.92; P < 0.01) and were inversely related to ETT size. Additionally, there was a significant correlation between pressure drop or resistance and kinematic viscosity (R = 0.99; P < 0.01). For LV in neonates these data can be used to select the optimum ETT size and PFC liquid depending OR the chosen ventilation strategy.

Persistent neuropsychological deficits following whiplash: evidence for chronic mild traumatic brain injury?

OBJECTIVE: To investigate claims of neuropsychological evidence for acquired brain damage (axonal degeneration) in chronic whiplash. DESIGN: Fifteen whiplash patients (Whiplash) were compared with 10 patients who had documented moderate-to-severe head injury (Mod-Sev), and with 24 patients who had chronic pain syndrome (CPS) and no history of head injury on two tests of mental efficiency considered highly sensitive to and specific for the subtle effects of brain trauma. All 3 groups, assessed 4 years after onset in a teaching hospital setting were matched for age, education, and IQ. Exclusion criteria included narcotics/benzo-diazepines or (suspected) malingering. Subjective ratings of depression and pain were collected as well as objective indices of outcome (return to work/school). MEASURES: Neuropsychological test scores were subjected to ANOVA followed by regression analysis regarding the possible effects of age, IQ, pain, and mood ratings. RESULTS: No differences between the Whiplash, Mod-Sev, or CPS groups on the neuropsychological tests emerged. IQ was strongly related to mental efficiency. Counterintuitively, Mod-Sev patients complained of less depression and pain than did Whiplash or CPS patients (where no differences were seen) and displayed a better outcome. Finally, although results from 3 of the original 18 patients in the Whiplash group were later discarded for malingering, no malingering was detected in the 2 other groups. CONCLUSIONS: The theory of neuronal degeneration in the etiology of whiplash-related cognitive complaints was not supported, nor was the specificity of neuropsychological tests in detecting the subtle effects of brain trauma.

Liquid ventilation: a comprehensive overview.

Despite advances in neonatology, some infants do not respond to current pharmacologic and ventilatory techniques. Others suffer chronic lung disease, require prolonged ventilatory support, and experience significant morbidity during infancy due to the elevated inflation pressures used to treat their respiratory problems. Over the past 30 years, results of studies in premature animals as well as clinical trials have demonstrated that ventilation with oxygenated perfluorochemical (PFC) fluids provides effective gas exchange and improved lung mechanics. PFC fluids are biologically inert, have a high gas solubility and a low surface tension, and are nonbiotransformable. With liquid ventilation, alveolar pressures are low because the high surface tension of the gas-lung interface in eliminated. Potential neonatal applications include surfactant deficiency, persistent pulmonary hypertension, meconium aspiration, diaphragmatic hernia, pneumonia, and a vehicle for drug delivery. In order to develop a nursing care plan for the liquid-ventilated infant, nurses need knowledge of the physiologic changes involved in liquid ventilation, as well as its mechanics.

A cross-sectional survey of condom use in conjunction with other contraceptive methods.

A cross-sectional survey of 3,136 women attending family planning clinics in Texas was conducted to examine past use of and future plans for use of condoms by partners during sexual intercourse for disease prevention in conjunction with other contraceptive methods. Following the receipt of clinical services, including counseling about family planning and disease prevention, both contraceptive and planned condom use reporting increased for the majority of subjects. However 22% of the sample indicated that they intended to reduce condom use in the future and instead use a contraceptive which protects from pregnancy but not from disease. Condom use was indicated more frequently for those who reported at least one risk factor for HIV, but 17% of those at risk indicated lower future condom use than past use. This suggests that without changes in risk behavior, these women will be at increased risk of HIV or another sexually transmitted disease.

PIP: During May 10-July 20, 1993, clinic staff interviewed 3136 women aged 12-45 attending 13 family planning clinics in southeastern Texas so researchers could determine the frequency of condom use for prevention of sexually transmitted diseases (STDs) in women using other forms of contraception for pregnancy prevention. 30% had had unprotected intercourse at least once in the last month. Clients who planned to always use a contraceptive method in the future increased from 58% to 83% after counseling. After counseling, 31% planned to always use a condom in the future. Before the visit, 10% had always used a condom. After counseling, condom use with oral contraceptives, IUD, diaphragm, cervical cap, implants, Depo Provera, or sexual sterilization increased from 28% to 42%. 35% of clients used condoms when they thought that protection was needed. 72% were currently in a monogamous relationship. 10% considered themselves not at risk of HIV. Women with one sexual partner tended to think that they were not at risk of HIV or not concerned about HIV. They were much less likely to intend to use condoms in the future with another method than their counterparts. Three women had HIV infection. 4% had genital herpes. 13% had had another STD. 260 women (8%) had had intercourse with partners engaging in risky behavior. 47% of clients had at least one risk factor for HIV (e.g., recent STD). After counseling, condom use increased among clients with risk factors for HIV. These same clients were also more likely to use condoms than those with no risk factors. 17% of these clients planned to reduce condom use in the future, however. 22% of clients planned to decrease condom use in the future and use a contraceptive method to protect against pregnancy rather than STDs. These findings show that many women at risk for STDs who request contraception do not protect themselves from STDs, indicating an additional unmet need. The researchers suggest that there should be research and development for intervention methods for women at risk for STDs who stop using condoms when they receive another contraceptive method.

One-year experience with subdermal contraceptive implants in the United States.

Women who received Norplant contraceptive implants from any of fifteen clinical settings in southeast Texas, U.S.A., were followed for one year to determine their reactions to the method. Of 1,385 who enrolled to receive Norplant implants, 1,253 had implants inserted. Side effects were reported by 78% of those receiving implants and 70% described changes in bleeding patterns. Spotting or irregular bleeding, weight gain and headaches were the conditions reported most frequently. Nine pregnancies were reported during the study period. Six of these, however, existed before the implants were inserted. At the one year anniversary, 143 of women receiving implants had had them removed. Those who discontinued method use were less satisfied, reported more side effects and were more likely to have planned to have another child, thus using the method for spacing, or to have had a change in their marital status while they were using the contraceptive. Providers should counsel patients to focus attention on plans for the future in selecting their contraceptive method. In addition, we recommend, as does the product's distributor, that providers confirm that patients are not pregnant prior to inserting implants.

External beam radiotherapy for incidental adenocarcinoma of the prostate discovered at transurethral resection.

This paper updates the results of 89 patients treated between 1967 and 1989 for incidental carcinoma discovered at transurethral resection of the prostate (Stanford stage T0 or AJC-UICC stage T1) with external beam irradiation. Twenty-two patients had Stanford T0 focal (less than 5% involvement of the prostatic chips) and 67 presented with Stanford T0 diffuse (5% or more involvement). Follow-up ranges from 4 months to 25.1 years, with a mean follow-up of 9.8 years. The actuarial local control for Stanford T0 focal is 100%, and 70% for Stanford T0 diffuse at 15 years. There was no difference in survival between Stanford T0 diffuse and T0 focal and the expected survival of an age-matched control population. Patients who were treated when younger than 65 had a similar local control and distant relapse when compared to those treated when 65 or older. There was no difference in local control, freedom from relapse, or disease-specific survival when the 38 patients who received irradiation to the prostate only are compared with the 29 who also received pelvic irradiation for Stanford T0 diffuse carcinoma. Patients with a Gleason score of 6 or more, when compared with those with a score of 5 or less, experienced more distant relapses and similar local control, suggesting that patients with a high grade tumor have occult metastases at presentation.

Composite (adenocarcinoid) tumors of the gastrointestinal tract.

Tumors of the gut with composite features of both adenocarcinoma and carcinoid have been recognized mainly in the appendix. There also have been isolated reports of similar tumors arising from other parts of the gastrointestinal tract. It is generally concluded that these tumors have better prognosis than adenocarcinomas of the gastrointestinal tract. We reported six patients with composite tumors arising from the stomach in one, small intestine in two, cecum in two, and rectum in one patient. Clinical presentations in each was suggestive of malignancy with extension to either serosa and/or lymph nodes. Metastasis to liver was present in two patients. Histologically, the tumor showed glands with surface microvilli resembling adenocarcinoma and also organoid pattern with neurosecretory granules in cells resembling carcinoid. Two patients died three and nine months after surgery. The clinical presentation, findings at operation, and the postsurgical course of these six patients reveal that these tumors behave more like an adenocarcinoma than carcinoid and do not appear to have a better prognosis than ordinary adenocarcinoma.

Effects of lithotripter fields on development of chick embryos.

Chick embryos at 72 h incubation were subjected to three double shock waves from a Wolf Model 2137.50 Electrohydraulic Lithotripter. The pressure amplitude at the embryo was adjusted by variation of the distance from the source to the embryo. After a total of 120 h of incubation, they were assessed for developmental abnormalities. Early deaths, delayed deaths and malformations were all significantly increased at pressures of 10 MPa with suggestions of possible effects at lower pressure levels.

Test for kidney hemorrhage following exposure to intense, pulsed ultrasound.

A recent study has found that the threshold for extravasation in mouse kidney tissues by exposure to a spark-generated shock wave is of the order of 3-5 MPa (peak positive pressure). Since the mode pressure used by commercial pulsed Doppler ultrasound units is approximately 5 MPa, it is essential to determine whether these observations are relevant to diagnostic ultrasound. Hence, a comparable study has been completed using the same pathological endpoints but with exposure to pulsed ultrasound (10 microseconds pulse length) at 1.2 MHz and 3.8 MHz in which peak positive pressures exceeded 10 MPa. At these levels the focal waves are in shock because of the nonlinear properties of the propagating medium. The results of the pulsed ultrasound study were negative. Although this finding is encouraging for the use of diagnostic ultrasound, the two studies eventually must be integrated into a single mechanistic picture before the limits of safety will be known.

Inhibitors of arachidonic acid lipoxygenase impair the stimulation of inositol phospholipid hydrolysis by the T lymphocyte mitogen phytohaemagglutinin.

Piriprost and nordihydroguiaretic acid (NDGA), specific inhibitors of arachidonate lipoxygenase, inhibited phytohaemagglutinin (PHA)-stimulated breakdown of inositol lipids in human T lymphocytes. The dual inhibitors eicosatetraynoic acid (ETYA) and BW 755C, which inhibit both lipoxygenase and cyclooxygenase, also had similar actions, whereas indomethacin and acetylsalicyclic acid, which inhibit cyclooxygenase alone, did not. The effects of lipoxygenase inhibitors and dual inhibitors were reversible. These agents did not inhibit phosphatidylinositol-4,5-bisphosphate-specific phospholipase C (PIP2-PLC) in vitro. Bromophenacyl bromide, and irreversible inhibitor of phospholipase A2, also abolished PHA-stimulated inositol lipid breakdown without affecting PIP2-PLC in vitro. The results are consistent with a role for the PHA-stimulated generation of arachidonic acid and its conversion to lipoxygenase metabolites (e.g. leukotrienes and/or hydroxyeicosatetraenoic acids) as intermediate steps in the signal transduction pathway between cell-surface mitogen receptors and the stimulation of PIP2-PLC in lymphocytes.

Hyaluronate accumulation and nerve-dependent growth during regeneration of larval Ambystoma limbs.

Hyaluronate-mediated expansion of the extracellular matrix has been suggested as an important element of growth and morphogenesis in several developing systems. In vitro, various growth factors have been shown to stimulate hyaluronate synthesis as well as cell proliferation. A similar link between proliferation and hyaluronate production during in vivo growth is difficult to demonstrate, because in most systems the source of growth-promoting factors is either not known or not amenable to experimental manipulation. During amphibian limb regeneration, cell proliferation depends upon paracrine release of factors from axons in the limb stump, and the nerve supply can be eliminated or augmented experimentally for study of growth in this system. Denervated and amputated limbs of larval salamanders do not begin to regenerate until distal areas of the limb stumps are reinnervated. We have used such limbs to examine the effect exerted by the reappearance of nerves on the amount of hyaluronate in the tissue undergoing the growth response. Hyaluronate was demonstrated by the metachromatic dye Ethyl Stains-all, which stains hyaluronate blue while sulfated glycosaminoglycans (GAGs) and proteins in the extracellular matrix stain various shades of violet, and by microspectrophotometry of alcian-blue-stained GAGs in serial sections pretreated with buffer or with Streptomyces hyaluronidase (SH) to remove hyaluronate specifically. Both methods showed little hyaluronate in the distal region of limb stumps prior to reinnervation, while reinnervated stumps had amounts of hyaluronate similar to those of control blastemas. Autoradiography of 3H-glucosamine-labeled limbs indicated that hyaluronate in the blastemas of reinnervated limb stumps included material newly synthesized by cells throughout the growing tissue.(ABSTRACT TRUNCATED AT 250 WORDS)

Influence of a calcium dependent protease inhibitor on platelet activation and secretion.

Continuous proteolysis resulting in consumption of major cytoskeletal proteins may be essential for platelet activation and aggregation. In this study we evaluated the effect of a known protease inhibitor, Leupeptin, on agonist induced platelet aggregation and secretion. Platelets exposed to 10 ugs/ml of Leupeptin did not aggregate in response to the action of thrombin (0.2 u/ml). However, a concentration of Leupeptin as high as 250 ugs/ml did not prevent arachidonate induced aggregation and secretion. Leupeptin (100 ugs/ml) effectively blocked thrombin (0.2 u/ml) induced elevation of cytosolic calcium, but did not affect arachidonate induced elevation of platelet intracellular calcium levels. At a concentration of 100 ug/ml, Leupeptin effectively blocked thrombin (0.5 u/ml) induced clot formation of platelet poor plasma, suggesting that it can exert its effect on thrombin by preventing fibrinogen degradation. Effective Ki for the competitive inhibition of thrombin induced hydrolysis of a chromogenic substrate, S2238, by Leupeptin was 2.4 uM. Leupeptin inhibition of platelet function was reversible by washing platelets free of the polypeptide. Results of our study demonstrate that Leupeptin inhibits thrombin induced platelet activation, probably by interfering with its proteolytic activity on the platelet surface membrane. However, inhibition of platelet surface membrane associated proteases did not prevent activation of platelets by other agonists.

Who cares? Nursing and sociology: the development of a symbiotic relationship.

The paper has three aims: to illustrate ways in which sociology may help nurses to achieve their primary objective: good patient care; to show how nursing can contribute to sociology; and to indicate some conditions for a healthy relationship between the two activities. After a brief discussion of the nature of sociology, intended for non-sociologists, four examples of ways in which sociology may be relevant to nursing are discussed: (i) Implications for nursing of changing patterns of disease, dependency and death; (ii) Social and cultural variations in perceptions of, and responses to, pain and disease; (iii) Organizational analyses, with particular reference to the importance of nurse-patient communication; (iv) Sociological studies of inter-personal relationships, illustrated by a study of student nurse training. Nursing is described as the major caring profession; as such it has inherent interest for sociologists interested in health care. However, its sociological interest is enhanced by the fact that it is permeated by paradoxes. Reference is also made to current debate on the most appropriate model for health care: the traditional medical model places relatively greater emphasis on cure than does nursing, with its relatively greater involvement with care. It is suggested that current patterns of disease and dependency increase the importance of the care model, and that nursing could play a crucial role in such a shift of emphasis. Having shown that sociology can make positive contributions to nursing, attention is drawn to certain dangers. Nursing should thus make sure that the sociology which it welcomes into its domain is academically sound, and not ideology in disguise. It is also suggested that nursing education should encourage more critical thinking, to enliven nurses' appreciation of what sociology has to offer, and to improve their ability to evaluate the quality of health care.