Psychopharmacological treatment of delirium to restore mental capacity.

The authors report four patient cases of delirium in which medications were used to restore mental capacity when life-or-death treatment decisions were required. Although extensive literature on substituted judgment exists for delirium and depression compromising capacity to make competent decisions, the authors could locate no articles proposing aggressive delirium treatment for restoring patients' capacity to participate in their own care. Without surgical intervention, all four of the authors' patients faced imminent death. Without psychopharmacologic banishment of the patients' deliria, proxies would have been asked whether the patients should undergo potentially lifesaving but high-risk procedures. The patients would have lost the opportunity to express their wishes about heroic lifesaving medical measures.

Natural killer cell function in women with vestibulitis.

OBJECTIVE: To assess natural killer (NK) cell activity in patients with vestibulitis. STUDY DESIGN: Twenty-two patients who met the International Society for the Study of Vulvar Disease criteria for vestibulitis and 17 age-, sex- and race-matched controls were recruited. NK cell activity was examined using a standard, four-hour 51Cr-release assay, freshly and after stimulation with interleukin 2 (IL2) or alpha interferon (IFN alpha). RESULTS: The subject samples had significantly decreased fresh NK cell activity (mean lytic units [LU]/10(6) peripheral blood leukocytes [PBLs] of 0.93 vs. 4.19, P < .001). This activity was augmented in response to either IFN or IL2. However, it remained significantly lower than in the control samples (12.07 vs. 20.6 LU/10(6) PBL, P = .007 for IL2 and 5.98 vs. 15.33 LU/10(6) PBL, P < .001 for IFN). This difference was not universal since the major histocompatibility-nonrestricted T killer cell activity of the subject samples was not significantly different from that in the control samples. CONCLUSION: This pilot study suggests that patients with vulvar vestibulitis have markedly decreased NK cell activity. Although this activity is increased in response to IL2 or IFN, it remains significantly impaired in comparison to the control samples.

Surgical glove powders differentially modulate macrophage and lymphocyte-derived cytokines and eicosanoids production in vitro.

The objective of the present study was to determine the effect of surgical glove powders Biosorb, Keoflo, and CaCO(3) and Hydrocote (a powder-free film; Biogel) on cytokine and eicosanoid production by lipopolysaccharide/phorbol 12-myristate 13-acetate activated and unactivated HL60, U937, and RPMI 1788 cells, human monocyte/macrophage, and B lymphocyte cell lines. The unactivated cell culture-conditioned media contained a low level of interleukin-1alpha and -1beta, granulocyte macrophage colony stimulating factor, and tumor necrosis factor-alpha, which significantly increased after activation (p < 0.05). Exposure of unactivated cells to glove powders or Hydrocote (100 microg/ml) had little effect. However, these compounds appeared to have multiple inhibitory and stimulatory action on the production of these cytokines and eicosanoids in lipopolysaccharide/phorbol 12-myristate 13-acetate activated cells. For instance, granulocyte macrophage colony stimulating factor production was inhibited only in U937 cells by Keoflo and CaCO(3), whereas, tumor necrosis factor-alpha production was stimulated by Biosorb and Keoflo in HL-60, and CaCO(3) was found to be predominantly inhibitory on tumor necrosis factor-alpha production by these cells (p < 0.05). Total transforming growth factor-beta(1) production was stimulated by Biosorb and Hydrocote in U937 and HL-60 cells, respectively, but inhibited by Keoflo in U937 cells. However, Biosorb and Keoflo inhibited transforming growth factor-beta(1) production in both HL-60 and RPMI 1788 cells, without any effect on active transforming growth factor-beta(1). With regard to eicosanoids, Biosorb and Keoflo stimulated prostaglandin E(2) production by RPMI 1788 cells, whereas it was inhibited by all glove powders in HL-60 cells. Thromboxane B(2) production was stimulated by Keoflo and inhibited by CaCO(3) and Hydrocote in U937 cells. Finally, Leukotriene B(4) synthesis was found to become stimulated by Keoflo, CaCO(3), and Hydrocote in both HL60 and RPMI 1788 cells (p < 0.05). These data indicate that exposure of activated, but not unactivated, macrophages and lymphocyte to surgical glove powders and Hydrocote differentially effects the release of cytokines and eicosanoids by these cells. Considering that cytokines and eicosanoids play an important role in mediating the inflammatory and immune responses of wound healing, complications arising from glove powder exposure in vivo may involve mechanisms which alter the type and level of cytokine and eicosanoid production.

Identification of epidermal growth factor, transforming growth factor-alpha, and epidermal growth factor receptor in surgically induced pelvic adhesions in the rat and intraperitoneal adhesions in the human.

OBJECTIVE: Our purpose was to determine the presence and cellular distribution of epidermal growth factor, transforming growth factor-alpha, and epidermal growth factor receptor in surgically induced pelvic fibrous adhesions in rat uterine horns subjected to burn, crush, and debridement injury and intraperitoneal fibrous adhesions formed to various organs in the human. STUDY DESIGN: A total of 15 injured and five uninjured rats were used in this study, and fibrous adhesions and intact peritoneum were removed for processing 2 weeks after surgery. Fibrous adhesions formed to uterine, ovarian, and oviductal tissues and the peritoneal wall from eight patients who had gynecologic surgery were also collected. The tissues were processed for immunohistochemical localization of epidermal growth factor, transforming growth factor-alpha, and epidermal growth factor receptor with specific antibodies to human and rat epidermal growth factor and transforming growth factor-alpha and the extracellular binding domain of the epidermal growth factor receptor. RESULTS: All the cell types in the rat fibrous adhesion immunostained for epidermal growth factor, transforming growth factor-alpha, and epidermal growth factor receptor. The highest immunostaining intensity for epidermal growth factor was associated with inflammatory cells infiltrated into the fibrous adhesion, followed by arteriole endothelial and smooth muscle cells, fascial striated muscle, and fibroblasts of the fibrous adhesion. In the uterine tissue at the site of injuries myometrial smooth muscle cells, in addition to inflammatory cells that migrated among stromal cells, also immunostained for epidermal growth factor. Fibrous adhesions also immunostained for transforming growth factor-alpha with three separate polyclonal antibodies to the amino and carboxy termini of transforming growth factor-alpha precursor and the mature transforming growth factor-alpha, with no substantial differences in their intensity and pattern compared with epidermal growth factor. The pattern and cellular distribution of epidermal growth factor receptor was similar to that seen for epidermal growth factor and transforming growth factor-alpha. Fibrous adhesions from patients with intraperitoneal adhesions immunostained for epidermal growth factor, transforming growth factor-alpha, and epidermal growth factor receptor with a pattern and intensity similar to that observed in fibrous adhesions in the rats. CONCLUSIONS: The data suggest that epidermal growth factor and transforming growth factor-alpha may play a key role both in normal mechanism of peritoneal repair after injury and formation and maintenance of fibrous adhesions.

Insulin-like growth factor I (IGF-I), IGF-I receptors, and IGF binding proteins 1-4 in human uterine tissue: tissue localization and IGF-I action in endometrial stromal and myometrial smooth muscle cells in vitro.

The objective of the present study was to elucidate the presence and cellular distribution of insulin-like growth factor I (IGF-I), IGF-I receptor (IGF-IR), and IGF binding proteins (IGFBPs) in human uterine tissue at various reproductive stages, and to determine the effect of IGF-I and its interaction with epidermal growth factor (EGF) and platelet-derived growth factor (PDGF) in endometrial stromal and myometrial smooth muscle cells in primary culture. Using specific antibodies, immunohistochemical observations indicated that luminal and glandular epithelial cells were the major sites of immunoreactive IGF-I, IGF-IR, and IGFBPs 1-4, followed by myometrial smooth muscle and endometrial stromal cells. The immunostaining intensity of IGF-I, IGF-IR, and IGFBPs in endometrial but not myometrial tissue was cycle-dependent and higher in the late proliferative and early/mid-secretory periods than in the late secretory and postmenopausal periods, with little immunostaining at the early proliferative phase of the menstrual cycle. Stromal and smooth cells in primary cell culture also contained immunoreactive IGF-I, IGF-IR, and IGFBPs. IGF-I at 10-100 ng/ml stimulated 3H-thymidine incorporation in quiescent stromal and smooth muscle cells with maximal effect at 100 ng/ml (p < 0.05). However, in the presence of 2% serum, which induces half-maximal stimulation, IGF-I (100 ng/ml) further increased the rate of 3H-thymidine incorporation in stromal but not smooth muscle cells (p < 0.05). The effect of IGF-I was significantly lower than that induced by EGF (10 ng/ml), PDGF-BB (10 ng/ml) and their combination (p < 0.005), and higher in stromal cells from proliferative, than secretory phase of the cycle in the presence of 2% fetal bovine serum, but not serum-free condition (p < 0.005). The effect of IGF-I on myometrial smooth muscle cells was significantly higher than that induced by EGF, but lower than that induced by PDGF-BB or by EGF+PDGF-BB, without the cycle specificity seen with stromal cells. EGF, PDGF-BB, and their combination with IGF-I, but not IGF-I alone, stimulated stromal and smooth muscle cell growth as determined by a cell proliferation assay. The results indicate that human uterine tissue at various reproductive stages contains immunoreactive IGF-I, IGF-IR, and IGFBPs 1-4. Although IGF-I alone was found to be a weak mitogenic factor for stromal and smooth muscle cells, by interacting with EGF and PDGF-BB in a cycle-dependent manner it may regulate the growth and differentiation of these and other uterine cell types.

Prognostic validity of short-term abstinence in alcoholism.

A demonstrated period of abstinence is often viewed as a good prognostic sign in alcoholism. For example, short-term abstinence is one factor often considered important as a selection criteria for alcoholics who are being evaluated as liver transplant candidates. However, the prognostic validity of short-term abstinence is unclear. We evaluated the effects of 3 and 6 months of abstinence on readmission rates in a series of 299 alcoholics following discharge from inpatient treatment. Readmission rates were stratified using a 3-factor model of alcoholism severity. This 3-factor model defined groups with 1-year readmission rates, ranging from 15.8% to 62.7%. Short-term abstinence did not have strong effects on readmission rates for the most severe alcoholics, nor did short-term abstinence produce clinically significant reduction for readmission rates for the least severe alcoholics. We conclude that short-term abstinence has minimal effect on prognosis for alcoholics with various levels of baseline severity.

Localization of transforming growth factor beta isoforms TGF-beta 1, TGF-beta 2, and TGF-beta 3 in surgically induced pelvic adhesions in the rat.

OBJECTIVE: To investigate the presence and cellular distribution of transforming growth factor (TGF)-beta s in surgically induced pelvic fibrous adhesions in rat uterine horns subjected to burn, crush, and debridement injury. METHODS: Thirty injured and 20 uninjured rats were treated postoperatively with intraperitoneal administration of either 2 micrograms/mL of recombinant human TGF-beta, 10 micrograms/mL TGF-beta neutralizing antibody, or phosphate-buffered saline + 500 micrograms rat serum albumin for 5 consecutive days. The intact (uninjured) and fibrous tissues were analyzed immunohistochemically for the presence of TGF-beta s using polyclonal antibodies to TGF-beta s 1-3. RESULTS: The intact peritoneum immunostained with a lower intensity than fibrous adhesive tissues for TGF-beta 1, TGF-beta 2, and TGF-beta 3. The immunoreactive TGF-beta s were present in fibroblasts, inflammatory cells infiltrated into the fibrous adhesion, and endothelial and smooth-muscle cells of the arterioles. In the uterine tissue at the site of injury, the following immunostained for TGF-beta s: uterine serosal tissue, myometrial smooth-muscle cells, endometrial luminal and glandular epithelial cells, and inflammatory cells. However, endometrial stromal cells did not immunostain for TGF-beta s. There were no substantial differences in immunostaining intensities of fibrous adhesive tissues in the TGF-beta group, neutralizing TGF-beta antibody group, and the controls. CONCLUSION: The data suggest that TGF-beta s may play a role in the formation and maintenance of fibrous adhesions following intraperitoneal injury.

The effect of surgical glove powder on proliferation of human skin fibroblast and monocyte/macrophage.

The effect of surgical glove powders (Biosorb, Keoflo, and CaCO3) and Hydrocote (powder-free lubricating agent, Biogel) was examined on human skin fibroblasts and monocyte/macrophage cell lines (U937 and HL-60). Glove powders (0.1-100 micrograms/ml) in the presence of 10% fetal bovine serum (FBS) had no significant effect on the rate of 3H-thymidine uptake and proliferation of these cells after 48 h and 7 days of exposure, respectively. However, they inhibited HL-60 growth after 10 days, and Biosorb and CaCO3 inhibited U937 after 10-21 days of exposure compared with control. In the presence of low serum (0.5%), Biosorb, but not Keoflo, CaCO3, and Hydrocote, inhibited HL-60 cells after the third day of exposure (p < 0.05), whereas they were without any effect on U937 cells. Further incubation resulted in a significant decrease in cell density in all treatments, as well as controls, because of cell death. In the presence of 2% serum, glove powder-treated HL-60 significantly increased in cell numbers during the first 3 days, and the cells became stationary thereafter, whereas Keoflo and CaCO3-stimulated U937 reached a maximal by 9 days of treatment. Coculturing of fibroblasts directly with macrophages (0.4-5 x 10(5) cells per dish) or incubation with macrophage culture-conditioned media (CCM) stimulated quiescent fibroblast growth equal to that induced by 10% and 0.5% serum, respectively (p < 0.05). However, incubation of fibroblasts with glove powder-treated HL-60 CCM (except CaCO3) inhibited (p < 0.05) and CCM from Biosorb-treated U937 stimulated (p < 0.05) fibroblast proliferation. The CCM from glove powder-treated HL-60 and U937 did not have any significant effect on the rate of 3H-thymidine incorporation into fibroblasts compared with controls. The present observations suggest that glove powder action on fibroblast and macrophage growth in vitro depends on both the serum concentration of the culture medium and the length of exposure. The results imply that glove powders may have an adverse effect in vivo by directly influencing the biologic activity of macrophages, as well as other cell types, leading to alterations in the early phases of wound healing.

Descriptive and predictive validity of a high-risk alcoholism relapse model.

A major problem with alcoholism treatment is the high rate of early recidivism to drinking and re-admission for alcoholism treatment. The objective of this study was to retest a model or predict early (within 6 months) re-admission to alcoholism treatment using a second independent sample. Additionally, we compared a high-risk alcoholism relapse (HAR) model (defined by chronicity of heavy drinking, daily alcohol consumption and previous treatment history) with three previously defined alcoholism typologies for descriptive and predictive validity. Male alcoholics (N = 299) admitted for treatment at a Veterans Affairs inpatient treatment program were interviewed and then followed for 6 months after discharge. The HAR model identified 107 (35.8%) alcoholics at high-risk for relapse prior to discharge. Of the HAR group 61% were re-admitted within 6 months compared to 28% of the low-risk alcoholism relapse (LAR) group (OR = 4.0, 95% CI = 2.4-6.8). The HAR group was older with a lower socioeconomic status, fewer legal problems, more physical and mental health problems and decreased evidence of social support. The HAR model was more successful than were the typologies for predicting early relapse. The HAR model demonstrates descriptive and predictive validity and compares favorably to existing typology models.

Cellular distribution of epidermal growth factor, transforming growth factor-alpha, and epidermal growth factor receptor in fascia and peritoneum during healing in the rat: an autoradiographic and immunohistochemical study.

The presence and cellular distribution of epidermal growth factor (EGF), TGF-alpha, and EGF-R were determined in the rat fascial and peritoneal tissue during healing of an incisional injury by means of immunohistochemistry and autoradiographic techniques. The immunostaining intensity for EGF in the regenerating wound area was substantially higher during the first 14 days, then decreased to near prewound levels during 14 to 35 days after surgery. Within the wound area, the most intense immunostaining occurred with inflammatory cells, followed by fascial striated muscle and arterioles, whereas fibroblasts in the regenerating area contained very low immunostaining intensity. The immunostaining pattern for TGF-alpha with the use of three separate polyclonal antibodies that were directed against the amino and carboxy termini of TGF-alpha precursor and a fragment of the mature 50-amino-acid form of TGF-alpha was similar to that seen with EGF and persisted until 28 days after injury. However, fibroblasts in the regenerating area immunostained intensely for TGF-alpha but not for EGF. Quantitative autoradiography of iodine 125-labeled EGF binding and immunohistochemical studies of the EGF-R with monoclonal antibodies that were directed against the extracellular binding domain of EGF-R demonstrated the presence of specific EGF-R in regenerating fascial and peritoneal tissue. Net grain density (100 microm(2)), representing specific binding of (125)I-EGF, was calculated for different cell types in the wound. The grain density over fascial striated muscle, migratory fibroblasts and peritoneal fibroblasts increased by two and one half, three, and four times, respectively, at 7 days and decreased to the values in adjacent unwounded tissue by 21 days after injury (p < 0.05). Immunostaining for the EGF-R generated similar patterns, which persisted for 14 days after injury. The grain density and immunostaining for EGF-R over the arterioles in the wound did not change during the course of healing and was similar to that of the uninjured regions. In summary, these observations indicate that the local levels of EGF, TGF-alpha, and EGF-R increase during the early phases of healing in fascial and peritoneal injury, which suggests a role for these growth factors in the normal mechanism of fascial/peritoneal wound healing and fibrous adhesion formation.

Important points in managed care contracts.

Health care is increasingly managed through some contractual relationship. Such contracts vary and the contracting entities may be clinics, universities, health maintenance organizations, individual practitioner organizations, preferred provider organizations, corporate health plans, or other structures. It is estimated that within 10 years more than 70 percent of all health care will be provided through some type of managed care plan.

Platelet-derived growth factor (PDGF), epidermal growth factor (EGF), and EGF and PDGF beta-receptors in human endometrial tissue: localization and in vitro action.

Human endometrial tissue and primary stromal cell culture contain immunoreactive epidermal growth factor (EGF), platelet-derived growth factor (PDGF)-AB as well as EGF and PDGF-beta receptors. The immunostaining for EGF, EGF receptor, and PDGF beta-receptor were associated with endometrial luminal and glandular epithelial and stromal cells, whereas only the stromal cells contain immunoreactive PDGF-AB. The immunostaining intensity of EGF, EGF receptor, and PDGF-AB was similar in both phases of the menstrual cycle, whereas, PDGF-beta receptor immunostaining was highest in proliferative phase and considerably reduced, particularly in luminal and glandular epithelial cells in the secretory phase. In addition primary stromal cell cultures express EGF, PDGF-AB, and contain EGF and PDGF-beta receptors, and very low levels of PDGF-alpha receptor. 3H-Thymidine incorporation indicate that after 48 h of incubation in serum-free medium approximately 75-80% of stromal cells are quiescent. Incubation of quiescent stromal cells with 10% fetal bovine serum stimulate 3H-thymidine incorporation in a time-dependent manner reaching maximal after 30-48 h, with a doubling time of 38.2 h. EGF (1.5-15 ng/ml) stimulates 3H-thymidine incorporation by quiescent stromal cells (P less than 0.001). This effect was significantly reduced at concentrations above 15 ng/ml (P less than 0.005). PDGF-AB (3-10 ng/ml) and PDGF-BB (0.5-10 ng/ml) also stimulate 3H-thymidine incorporation in quiescent stromal cells compared to controls (P less than 0.005). The action of EGF (15 ng/ml) and PDGF-AB (10 ng/ml) was time dependent, reaching maximal after 36 and 48 h of incubation (P less than 0.002). Addition of PDGF-AB (10 ng/ml) to EGF (15 ng/ml) significantly enhanced the action of EGF or PDGF-AB used individually (P less than 0.001). 17 beta-estradiol or progesterone at 1 microM did not stimulate 3H-thymidine incorporation, although they were stimulatory in combination (P less than 0.001), they did not alter the action of EGF or PDGF when added in combination. These observations provide further evidence that human endometrial tissue contains specific immunoreactive EGF receptors. It also demonstrates the presence of immunoreactive EGF, PDGF-AB, and PDGF-beta receptors in endometrial tissue as well as stromal cells in primary culture. Both EGF and PDGF are mitogenic for endometrial stromal cells, suggesting an autocrine/paracrine role in modulation of endometrial cell growth and differentiation.

Presence of epidermal growth factor, platelet-derived growth factor, and their receptors in human myometrial tissue and smooth muscle cells: their action in smooth muscle cells in vitro.

Immunohistochemical observations indicate that human myometrial smooth muscle cells express epidermal growth factor (EGF) and platelet-derived growth factor (PDGF)-AB and contain EGF and PDGF-beta receptors with no variation in intensity with phases of the menstrual cycle. Furthermore, immunofluorescent microscopic studies revealed that primary myometrial smooth muscle cell cultures also express EGF, PDGF-AB, and contain EGF and PDGF-beta, but not alpha-receptor. Incubation of subconfluent smooth muscle cells in serum-free medium leads to quiescence within 48 h as demonstrated by 3H-thymidine incorporation and labeling index. Exposure of quiescent cells to 10% fetal bovine serum stimulates resumption of DNA synthesis and proliferation in a time-dependent manner with a doubling time of 41.6 h. EGF (1.5-50 ng/ml) and PDGF-AB (1-10 ng/ml) in a dose- and time-dependent manner significantly stimulated 3H-thymidine incorporation by quiescent myometrial smooth muscle cells (P less than 0.05). Combinations of EGF (15 ng/ml) and PDGF-AB (10 ng/ml) significantly increased 3H-thymidine incorporation induced by either growth factor alone (P less than 0.05). PDGF-BB at 10 ng/ml also stimulated 3H-thymidine incorporation and its effect was similar to that induced by PDGF-AB at the same concentration. 17 beta-Estradiol (E2) at 1 microM inhibited 3H-thymidine incorporation by the smooth muscle cells (P less than 0.05). E2 also reduced the stimulatory effect of EGF (15 ng/ml) and PDGF (3 ng/ml). Progesterone at 1 microM either alone or in combination with E2 did not have any effect on 3H-thymidine incorporation or alter the mitogenic action of EGF and PDGF. The effect of EGF and PDGF on cell growth and 3H-thymidine incorporation by myometrial smooth muscle cells was independent of phases of the menstrual cycle. In summary, the results of present studies indicate that human myometrial tissue and myometrial smooth muscle cells in primary culture locally produce EGF and PDGF-AB and contain EGF and PDGF-beta, but not alpha-receptors. Moreover, the myometrial smooth muscle cells in culture respond to the mitogenic action of EGF and PDGF.

Selection of incisions for gynecologic procedures.

Progress is being made in the employment of abdominal incisions. The use of mass closure has greatly decreased the incidence of disruption. The avoidance of subcutaneous sutures has likewise decreased the rate of wound infections, and modern aggressive management has lessened the time that patients must contend with incisional abscesses when they do occur. There will always be considerable discussion and debate on the choice of an abdominal incision. However, the primary consideration remains always to choose and construct a surgical incision large enough to operate through comfortably and effectively.

Tissue reactivity and degradation patterns of absorbable vascular ligating clips implanted in peritoneum and rectus fascia.

Absorbable vascular ligating clips are finding increasing use in intraabdominal surgery. We report the results of a light and scanning electron microscope investigation of the tissue reactivity and clip degradation patterns of two such materials, Absolok (polydioxanone) and Lactomer (copolymer of glycolic and lactic acid), implanted in the fascia and peritoneum of rabbits for intervals of 2 to 70 days. Cellular response to the clips, defined as the number of inflammatory cells/10(4) microns 2, was maximum at day 4 postimplantation, then gradually declined as the duration of implantation increased. This pattern, seen with both types of clips, was similar to that seen with polydioxanone (PDS) suture, but significantly greater than that associated with polypropylene (Prolene) suture. Although cellular response to the clips was greater in peritoneum than in fascia, especially on two occasions associated with adhesion formation, this was not statistically significant. Based on our morphological observations, the signs of clip degradation which were indicated by the appearance of surface crazing and cracks occurred earlier in peritoneum than in fascia.

Stress relaxation of organic suture materials.

Sutures fabricated from synthetic polymeric materials exhibit the phenomenon of stress relaxation, that is, when held under tension at a fixed elongation, there is a gradual realignment of the microstructure to accommodate the developed tensile stress. This property has been characterized for three modern suture materials, polypropylene, polydioxanone and poly(glycolic acid). All three materials exhibited stress relaxation but to different degrees, with polypropylene exhibiting the greatest stress relaxation (to approximately 40% of the initial load). The initial rate of stress relaxation increased with the rate of loading but the residual stress level was found to be independent of elongation rate except at extremely low rates of loading.

Chromic gut pelviscopic loop ligature. Effect of the number of pulls on the tensile strength.

The failure load of a pelviscopic loop ligature (PLL) was determined after tightening the slip knot with one, two or three pulls. The PLL showed a significant decrease in strength when tightened with three or more pulls. In each group some PLLs failed from slippage rather than from fracture of the suture material at the base of the knot. Slippage occurred more frequently with each additional pull. The findings indicate that the surgeon should apply only one pull on the device for the most secure knot. In addition, there was no strength difference between the suture material itself and the junction of the suture and its plastic tail grip. The plastic tail grip of the PLL will not release the tail end of the suture material before either the suture material or the slip knot fails.

In vivo and in vitro degradation of monofilament absorbable sutures, PDS and Maxon.

Two new absorbable monofilament suture materials polydioxanone and Maxon are being employed increasingly in abdominal surgery because of increased strength retention and decreased tissue reactivity compared with previously available materials. As part of our investigation of the behaviour of suture materials, 3-0 sutures of polydioxanone and Maxon were enclosed in nylon pouches, a technique developed for in vivo experiments to prevent cellular interaction with implanted devices. The pouched sutures were gas sterilized, then implanted in either the extrafascial space or peritoneal cavity for periods of 1-5 wk. Sterilized sutures were also incubated in Ringer's lactate at 37 degrees C. Tensile strength of the exposed sutures was measured. For a given suture material and duration of incubation, there was no significant difference in tensile strength degradation among the three test environments. Although the strength of unexposed Maxon is greater than that of polydioxanone, the residual strength of Maxon decreases more rapidly in use, so that, after 2 wk, the strength of polydioxanone is greater. Scanning electron microscope examination of the suture surfaces reveals that polydioxanone develops surface crazing with time, whereas the surface morphology of Maxon remains relatively unaltered.