Analysis of the operation of the SCD Response intermittent compression system

The work assessed the performance of the Kendall SCD Response intermittent pneumatic compression system for deep vein thrombosis prophylaxis, which claimed to set its cycle according to the blood flow characteristics of individual patient limbs. A series of tests measured the system response in various situations, including application to the limbs of healthy volunteers, and to false limbs. Practical experimentation and theoretical analysis were used to investigate influences on the system functioning other than blood flow. The system tested did not seem to perform as claimed, being unable to distinguish between real and fake limbs. The intervals between compressions were set to times unrealistic for venous refill, with temperature changes in the cuff the greatest influence on performance. Combining the functions of compression and the measurement of the effects of compression in the same air bladder makes temperature artefacts unavoidable and can cause significant errors in the inter-compression interval.     

Effect of prostaglandin E2 on agonist-stimulated cAMP accumulation in the distal convoluted tubule isolated from the rabbit kidney

The effects of calcitonin, vasoactive intestinal peptide (VIP), parathyroid hormone (PTH) and isoprenaline on intracellular cAMP accumulation were determined in the distal tubule (DCT) microdissected from collagenase-treated rabbit kidney. In DCTb (the initial bright portion) calcitonin (10 ng/ml) elicited a highly reproducible response 203.7±19.1 fmol cAMP mm^–1 4 min^–1 (SE, N=13) whereas VIP-induced cAMP accumulation was less and more variable from one experiment to another (1 M, 97.2±17.8 fmol mm^–1 4 min^–1, SE, N=12). When used in combination, these two agonists were non-additive, indicating stimulation of a single pool of cAMP in DCTb. In DCTg, (granular) which consists of at least two cell types, PTH (100 nM) elicited a marked, reproducible accumulation of cAMP (154.3±27.0 fmol mm^–1 4 min^–1; SE, N=5). Isoprenaline (1 M) and VIP (1 M) induced much smaller increases in cAMP levels 20.9±2.7 and 29.4±4.1 fmol mm^–1 4 min^–1 (SE, N=5) respectively, and, when used in combination, were non-additive, demonstrating that VIP and isoprenaline are active on the same cell type. In DCTb, prostaglandin E₂ (PGE₂) inhibited both calcitoninand VIP-stimulated cAMP accumulation (calcitonin 57.8±2.7% inhibition, SE, N=16; VIP, 80.6±2.1% inhibition, SE, N=5). The EC₅₀ values for calcitonin were 1.21±0.33 ng/ml and 1.83±0.25 ng/ ml (SD, N=3) in the absence and presence of PGE₂ (300 nM) respectively with an IC₅₀ for PGE₂ of 26.3±6.3 nM (SE, N=4). In contrast, no effects of PGE₂ were seen in DCTg vis à vis PTH, isoprenaline or VIP. The percentage inhibition of calcitonin-stimulated cAMP accumulation by PGE₂ was of the same order in the presence of isobutylmethylxanthine (an inhibitor of all types of phosphodiesterase), Ro 20-1724 (inhibitor of low-K _m cAMP-specific phosphodiesterase) or in the absence of inhibitor. Preincubation of DCTb with pertussis toxin for up to 8 h in different experimental conditions did not relieve the inhibition by PGE₂. Protein kinase C activation by phorbol ester did not attenuate calcitonin responses. These data demonstrate that the inhibition by PGE₂ of cAMP production is restricted to the initial portion (DCTb) of the distal convoluted tubule and is effective on both calcitonin and VIP responses. When tested in the presence of Ro 20-1724, ionomycin, A₁-adenosine, ₂-adrenergic and muscarinic agonists were without effect on calcitoninand PTH-stimulated cAMP accumulation in DCTb and DCTg respectively.     

Immunity to type IX collagen in rodents: a study of type IX collagen for autoimmune and arthritogenic activities

Type IX collagen (CIX), a cartilage-specific glycoprotein, constitutes ≤ 10% of cartilage collagen. To ascertain whether CIX can induce arthritis as shown for type II and XI collagen (CII and CXI), outbred rats were sensitized with bovine, chick and human CIX; inbred rats, mice, and guinea pigs were sensitized with bovine CIX. Mice and guinea pigs proved resistant to arthritis, as did rats sensitized with CIX/Freund's incomplete adjuvant (FIA). Arthritis was seen in rats when 100 μg of Mycobacterium tuberculosis (Mtb) were added to FIA, but seldom with smaller doses of Mtb, suggesting the arthritis was adjuvant-induced. High levels of antibodies to rat CIX, containing complement-fixing subclasses, were detected in rat sera in addition to DTH and lymphocyte proliferation responses to rat CIX. Given the potential for CIX-induced disease, CIX-sensitized rats were injected intraperitoneally with lipopolysaccharide (LPS) to stimulate proinflammatory cytokine release, and intra-articularly with rat CIX to stimulate arthritis. LPS stimulation was ineffective; however, intra-articularly injected CIX produced transient synovitis. When rats with stable adjuvant arthritis were sensitized with CIX/FIA, significant increases in paw volume were measured compared with controls given CI/FIA. Immunohistochemical studies of actively and passively sensitized rats revealed deposits of CIX antibody, but not C3, at the joint margins where proteoglycan staining was weak. Together, these findings suggest that autoimmunity to CIX, in contrast to CII and CXI, is not directly pathogenic but may contribute to joint injury provided arthritis is initiated by an independent disease process.     

Complex consultations and the ‘edge of chaos’

Complexity theory has attracted considerable attention in recent years, both within medicine and in the wider world. Its themes of uncertainty and non-linearity resonate deeply with the experience of working in general practice. Describing the consultation as a complex, adaptive system provides a coherent theoretical basis for understanding the consultation, which has so far been lacking. Understanding the consultation as a complex, adaptive system offers insights into the consultation of that may prove to be of practical use to clinicians.     

Distribution of vasoactive intestinal peptide-sensitive adenylate cyclase activity along the rabbit nephron

The effect of vasoactive intestinal peptide (VIP) upon adenylate cyclase (AC) activity has been determined in defined microdissected renal tubules isolated from collagenase-treated rabbit kidneys. In the presence of 10 M GTP, 1 M VIP gave marked stimulations of AC over basal values in the bright portion of the distal convoluted tubule (DCTb) (10.1-fold), and in the collecting tubule isolated from the inner stripe of the outer medulla (OMCTi, 7.8-fold). Less pronounced effects of VIP were found in the medullary collecting tubule isolated from the outer stripe (2.5-fold) and in the granular portion of the distal convoluted tubule (2.0-fold). VIP stimulation of AC activity in these segments amounted to 25 to 40% of the effect elicited by other agonists (arginine vasopressin, calcitonin or parathyroid hormone) in their respective target segments. A low response to VIP was observed in the cortical thick ascending limb (1.8-fold) which represented less than 5% of the calcitonin-stimulated AC activity. In the thin descending limb VIP produced a slight and variable stimulation of AC. VIP was without effect upon AC in the convoluted and straight portions of the proximal tubule, the medullary thick ascending limb and the cortical collecting tubule. Halfmaximal stimulation of AC by VIP was observed at 26±10 nM (n=3) in OMCTi and at 19 nM (n=2) in DCTb. Related peptides glucagon, secretin and PHI gave lower stimulations of AC compared to VIP in OMCTi. Conversely for rat OMCTi, under identical conditions, glucagon was much more effective than VIP.     

Terminal deletion (14)(q32.3): a new case.

A mildly dysmorphic, 2 year old girl with mental retardation was found to have a small de novo terminal deletion of the long arm of chromosome 14, del(14)(q32.3). She was found to have features in common with two previous terminal deletion cases and particularly with the well documented ring 14 syndrome, although seizures, a characteristic feature of ring 14, were notably absent.     

Paromomycin and Geneticin Inhibit Intracellular Cryptosporidium parvum without Trafficking through the Host Cell Cytoplasm: Implications for Drug Delivery

Cryptosporidium parvum, which causes intractable diarrhea and lethal wasting in people with AIDS, occupies an unusual intracellular but extracytoplasmic niche. No reliable therapy for cryptosporidiosis exists, though the aminoglycoside paromomycin is somewhat effective. We report that paromomycin and the related compound geneticin manifest their major in vitro anti-C. parvum activity against intracellular parasites via a mechanism that does not require drug trafficking through the host cell cytoplasm. We used both normal and transformed aminoglycoside-resistant Caco-2 or MDBK cells in these studies. Timed-exposure experiments demonstrated that these drugs inhibit intracellular but not extracellular parasites. Apical but not basolateral exposure of infected cells to these drugs led to very significant parasite inhibition, indicating an apical topological restriction of action. We estimated intracytoplasmic concentrations of paromomycin, using an intracellular bacterial killing assay, and found that C. parvum infection did not lead to increased paromomycin concentrations compared to those in uninfected cells. Global [³H]paromomycin uptake by Caco-2 cells was ~200-fold higher than the estimated intracytoplasmic paromomycin concentration, suggestive of host cell vesicular uptake and concentration (as has been reported with other cell lines). However, preinfection exposure of Caco-2 cells to paromomycin did not result in subsequent inhibition of parasite development, indicating that if exogenous paromomycin enters the infected host cell vesicular compartment, it does not effectively communicate with the parasite. Thus, the apical membranes overlying the parasite and parasitophorous vacuole may be the unsuspected major route of entry for paromomycin and may be of importance in the design and discovery of novel drug therapies for the otherwise untreatable C. parvum.     

Women''s decisions about whether or not to take hormone replacement therapy: influence of social and medical factors.

BACKGROUND. General practitioners have been described as reluctant to prescribe hormone replacement therapy although its use is widely discussed and advocated in the popular media. AIM. This study set out to identify women's perceptions of media coverage of hormone replacement therapy; the people influencing women's decisions about therapy and women's sources of information; their general practitioners' attitudes to therapy; and women's experiences of the primary health care team in relation to hormone replacement therapy. METHOD. In 1993, a postal questionnaire survey was undertaken of 1649 women aged between 20 and 69 years registered with eight general practices in Stockton-on-Tees. RESULTS. A total of 1225 women (74%) returned questionnaires. Women considered that the media portrayed mainly positive images of hormone replacement therapy. A substantial minority of women found the media information unhelpful (30%) or felt that it was incorrect (17%). General practitioners and practice nurses were most frequently considered to be the most important people in helping women decide about taking therapy, but relatives and friends were also important; 41% of women named no one. The media, friends and relatives were most commonly cited as the main sources of information about therapy. Of the women who had discussed hormone replacement therapy with their general practitioner, 65% felt that their general practitioner was in favour of its use for relieving menopausal symptoms. Two thirds of women felt they had had enough time and information when discussing hormone replacement therapy with their general practitioner and/or practice nurse. CONCLUSION. Women did not seem to perceive any resistance from their general practitioner to the prescribing of hormone replacement therapy. Although women gathered information about therapy from sources other than their doctor, doctors have an important role, as providers of the therapy, in listening to women and helping them to make their own decision about whether or not to take hormone replacement therapy.     

The spindle-shaped cells in cutaneous Kaposi''s sarcoma. Histologic simulators include factor XIIIa dermal dendrocytes.

Kaposi's sarcoma is a neoplasm that develops as multifocal lesions, often involving the skin, characterized by a complex histologic picture including numerous vascular spaces, perivascular and interstitial spindle-shaped cells, and extravasated erythrocytes, lymphocytes, and plasma cells. Using an antibody against factor XIIIa, which identifies dermal dendrocytes, numerous factor XIIIa-positive dermal dendrocytes were detected among the spindle-shaped cells in 12 acquired immune deficiency syndrome (AIDS)-associated, and five non-AIDS-associated Kaposi's sarcoma lesions. The factor XIIIa-positive dermal dendrocytes were also increased in histologic simulators of Kaposi's sarcoma such as dermatofibroma, angiomatoid malignant fibrous histiocytoma, granuloma annulare, and early wound healing, but were absent in keloids. The increased number of dermal dendrocytes, which are often in an angiocentric configuration and which also express CD4, lymphocyte function associated antigen-1 (LFA-1), and Leu M3 in Kaposi's sarcoma, may be important to the angioproliferative response. The results suggested that the spindle-shaped cells that are present in a variety of cutaneous lesions are dermal dendrocytes and belong to the reticuloendothelial system, unlike other mesenchymal cell types such as the endothelial cell. Apparently a diverse array of stimuli, including human immunodeficiency virus type-1 (HIV-1) infection and trauma, can stimulate the accumulation of factor XIIIa expressing dermal dendrocytes in the skin. These cells can then participate in different stages of a variety of cutaneous alterations including Kaposi's sarcoma, dermatofibroma, granuloma annulare, and early wound healing. Thus, the factor XIIIa-positive dermal dendrocyte is a common cellular denominator among diverse clinical entities that share some histologic features.     

Effects of all-trans retinoic acid and Ca++ on human skin in organ culture.

In this study, we have established an organ culture model of human skin and examined the effects of both all-trans retinoic acid (RA) and extracellular Ca++ on the epidermal and dermal components of the organ-cultured skin. Our data show that while organ cultures maintained in serum-free, growth factor-free culture medium containing 0.15 mM Ca++ degenerated rapidly, those treated with concentrations of RA that have been shown previously to stimulate fibroblast and keratinocyte proliferation in monolayer culture (J Invest Dermatol 1989, 93:449; 1990, 94:717; Am J Pathol 1990, 136:1275) demonstrated a healthy appearance for up to 12 days. Degeneration of the control cultures was characterized by separation of the epidermis from the underlying dermis, progressive cell necrosis leading to a complete absence of viable cells from both the dermal and epidermal compartments, disintegration and fibrillation of the dermal connective tissue, and a cessation of protein synthesis. RA-treated organ cultures contained large numbers of healthy-appearing cells in both the epidermal and dermal compartments. One or several layers of viable basal cells in the epidermis could be seen at least through day 12. However, the upper layers of the epidermis frequently separated from the cells in the basal layer. The dermal connective tissue was histologically well-preserved. Furthermore, the level of protein synthesis was higher in the RA-treated cultures than in the control cultures. In addition to treating organ cultures with RA, other cultures were exposed to serum-free, growth factor-free culture medium containing 1.4 mM Ca++. The presence of the elevated Ca++ concentration also preserved cellular and connective tissue structures in the dermal and epidermal compartments. In comparison to RA there was better preservation of the overall epidermal structure. The upper layers of epidermal cells did not separate from the basal cells, and the various stages of epithelial differentiation could be seen. Histologically, the dermis was well-preserved in the presence of elevated extracellular Ca++. Specimens treated with a combination of Ca++ and RA demonstrated features consistent with the features induced by each treatment separately. This included an expanded basal layer of epithelial cells and a prominent keratotic layer with a fairly orderly pattern of differentiation. The tendency of the upper epidermis to separate from the basal cells was partially mitigated. Taken together, these data indicate that both RA and extracellular Ca++ act to prevent the degeneration of human skin in organ culture but probably do so through different mechanisms.