P146 ROBOTIC REPAIR OF COMPLICATED INGUINAL HERNIAS

Aim

In this video, the authors provide an educational demonstration on the use of robotic surgery in management of two patients with complicated and recurrent inguinal hernias. The two patients demonstrated in these videos show the benefits of use of robotics in the approach to a patient with a recurrent hernia after previous open repair with plug and patch method as well as repair in a very obese patient with large hernias causing obstruction of the left ureter.

Material and Methods

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Results

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Conclusions

Robotic surgery is an emerging technology in surgery and can be a useful modality in treating patients with complex and recurrent inguinal hernias. Furthermore, the visualization in these complex cases can be helpful in identifying the important structures during dissection. Regardless of technique, the two videos presented demonstrate a complex dissection which may be needed when repairing recurrent or very large inguinal hernias.

Water Vapor, Clouds, and Saturation in the Tropical Tropopause Layer

The goal of this investigation is to understand the mechanism behind the observed high relative humidity with respect to ice (RHi) in the tropical region between ~14 km (150 hPa) and the tropopause, often referred to as the tropical tropopause layer (TTL). As shown by satellite, aircraft and balloon observations, high (>80%) RHi regions are widespread within the TTL. Regions with the highest RHi are co-located with extensive cirrus. During boreal winter, the TTL RHi is highest over the Tropical Western Pacific (TWP) with a weaker maximum over South America and Africa. In the winter, TTL temperatures are coldest and upward motion is the greatest in the TWP. It is this upward motion, driving humid air into the colder upper troposphere that produces the persistent high RHi and cirrus formation. Back trajectory calculations show that comparable adiabatic and diabatic processes contribute to this upward motion. We construct a bulk model of TWP TTL water vapor transport that includes cloud nucleation and ice microphysics that quantifies how upward motion drives the persistent high RHi in the TTL region. We find that atmospheric waves triggering cloud formation regulate the RHi, and that convection dehydrates the TTL. Our forward domain-filling trajectory (FDF) model is used to more precisely simulate the TTL spatial and vertical distribution of RHi. The observed RHi distribution is reproduced by the model and we show that convection increases RHi below the base of the TTL with little impact on the RHi in the TTL region.

Pinning and depinning: From periodic to chaotic and random media

We study the propagation of dissipative structures in inhomogeneous media with a focus on pinning and depinning transitions. We model spatial complexity in the medium as generated by dynamical systems. We are thus able to capture transitions from periodic to quasiperiodic, to homoclinic and heteroclinic, and to chaotic media. Depinning bifurcations exhibit universal laws depending on extreme value statistics that are encoded in the dimension of ergodic measures, only. A key condition limiting this approach bounds spatial Lyapunov exponents in terms of interface localization, and we explore the breakdown of smoothness and universality when this condition is violated and fluctuations in the medium occur on length scales shorter than a typical interface width.

Water Production Activity of Nine Long-Period Comets from SOHO/SWAN Observations of Hydrogen Lyman-alpha: 2013-2016

Nine recently discovered long-period comets were observed by the Solar Wind Anisotropies (SWAN) Lyman-alpha all-sky camera on board the Solar and Heliosphere Observatory (SOHO) satellite during the period of 2013 to 2016. These were C/2012 K1 (PanSTARRS), C/2013 US10 (Catalina), C/2013 V5 (Oukaimeden), C/2013 R1 (Lovejoy), C/2014 E2 (Jacques), C/2014 Q2 (Lovejoy), C/2015 G2 (MASTER), C/2014 Q1 (PanSTARRS) and C/2013 X1 (PanSTARRS). Of these 9 comets 6 were long-period comets and 3 were possibly dynamically new. Water production rates were calculated from each of the 885 images using our standard time-resolved model that accounts for the whole water photodissociation chain, exothermic velocities and collisional escape of H atoms. For most of these comets there were enough observations over a broad enough range of heliocentric distances to calculate power-law fits to the variation of production rate with heliocentric distances for pre- and post-perihelion portions of the orbits. Comet C/2014 Q1 (PanSTARRS), with a perihelion distance of only ~0.3 AU, showed the most unusual variation of water production rate with heliocentric distance and the resulting active area variation, indicating that when the comet was within 0.7 AU its activity was dominated by the continuous release of icy grains and chunks, greatly increasing the active sublimation area by more than a factor of 10 beyond what it had at larger heliocentric distances. A possible interpretation suggests that a large fraction of the comet's mass was lost during the apparition.

Improvement of Treatment Outcomes after Implementation of a Massive Transfusion Protocol: A Level I Trauma Center Experience

We assessed the effectiveness of the implementation of an institutional massive transfusion protocol (MTP) for resuscitation with a 1:1:1 transfusion ratio of packed red blood cell (PRBC), fresh frozen plasma, and platelet units. In a Level I trauma center database, all trauma admissions (2004–2012) that received massive transfusions (≥10 units PRBCs in the first 24 hours) were reviewed retrospectively. Demographic data, transfusion ratios, and outcomes were compared before (PRE) and after (POST) MTP implementation in May 2008. Age, sex, and mechanism of injury were similar between 239 PRE and 208 POST trauma patients requiring massive transfusion. Transfusion ratios of fresh frozen plasma:PRBC and platelet:PRBC increased after MTP implementation. Among survivors, MTP implementation shortened hospital length of stay from 31 to 26 days (P = 0.04) and intensive care unit length of stay from 31 to 26 days (P = 0.02). Linear regression identified treatment after (versus before) implementation of MTP as an independent predictor of decreased ventilator days after adjusting for age, Glasgow Coma Scale, and chest Abbreviated Injury Score (P < 0.0001). Modest improvement in ratios likely does not account for all significant improvements in outcomes. Implementing a standardized protocol likely impacts automation, efficiency, and/or timeliness of product delivery.

Improvement of Treatment Outcomes after Implementation of a Massive Transfusion Protocol: A Level I Trauma Center Experience

We assessed the effectiveness of the implementation of an institutional massive transfusion protocol (MTP) for resuscitation with a 1:1:1 transfusion ratio of packed red blood cell (PRBC), fresh frozen plasma, and platelet units. In a Level I trauma center database, all trauma admissions (2004-2012) that received massive transfusions (≥10 units PRBCs in the first 24 hours) were reviewed retrospectively. Demographic data, transfusion ratios, and outcomes were compared before (PRE) and after (POST) MTP implementation in May 2008. Age, sex, and mechanism of injury were similar between 239 PRE and 208 POST trauma patients requiring massive transfusion. Transfusion ratios of fresh frozen plasma:PRBC and platelet:PRBC increased after MTP implementation. Among survivors, MTP implementation shortened hospital length of stay from 31 to 26 days (P = 0.04) and intensive care unit length of stay from 31 to 26 days (P = 0.02). Linear regression identified treatment after (versus before) implementation of MTP as an independent predictor of decreased ventilator days after adjusting for age, Glasgow Coma Scale, and chest Abbreviated Injury Score (P < 0.0001). Modest improvement in ratios likely does not account for all significant improvements in outcomes. Implementing a standardized protocol likely impacts automation, efficiency, and/or timeliness of product delivery.

Risk of diabetes mellitus associated with disease-modifying antirheumatic drugs and statins in rheumatoid arthritis

OBJECTIVE

To investigate the rate of incident diabetes mellitus (DM) in patients with rheumatoid arthritis (RA) and the impact of disease-modifying antirheumatic drug (DMARD) and statin treatments.

METHODS

We studied patients with RA and ≥1 year participation in the National Data Bank for Rheumatic Diseases without baseline DM from 2000 through 2014. DM was determined by self-report or initiating DM medication. DMARDs were categorised into four mutually exclusive groups: (1) methotrexate monotherapy (reference); (2) any abatacept with or without synthetic DMARDs (3) any other DMARDs with methotrexate; (4) all other DMARDs without methotrexate; along with separate statin, glucocorticoid and hydroxychloroquine (yes/no) variables. Time-varying Cox proportional hazard models were used to adjust for age, sex, socioeconomic status, comorbidities, body mass index and RA severity measures.

RESULTS

During a median (IQR) 4.6 (2.5-8.8) years of follow-up in 13 669 patients with RA, 1139 incident DM cases were observed. The standardised incidence ratio (95% CI) of DM in patients with RA (1.37, (1.29 to 1.45)) was increased compared with US adult population. Adjusted HR (95% CI) for DM were 0.67 (0.57 to 0.80) for hydroxychloroquine, 0.52 (0.31 to 0.89) for abatacept (compared with methotrexate monotherapy), 1.31 (1.15 to 1.49) for glucocorticoids and 1.56 (1.36 to 1.78) for statins. Other synthetic/biological DMARDs were not associated with any risk change. Concomitant use of glucocorticoids did not alter DM risk reduction with hydroxychloroquine (HR 0.69 (0.51 to 0.93)).

CONCLUSIONS

In RA, incidence of DM is increased. Hydroxychloroquine and abatacept were associated with decreased risk of DM, and glucocorticoids and statins with increased risk.

Validation of a System to Predict Recanalization After Endovascular Treatment of Intracranial Aneurysms

BACKGROUND

With increasing use of endovascular techniques in the treatment of ruptured and unruptured aneurysms, the issue of obliteration efficacy has become increasingly important. We have previously reported the Aneurysm Recanalization Stratification Scale, which uses accessible predictors including aneurysm-specific factors (size, rupture, and intraluminal thrombosis) and treatment-related features (treatment modality and immediate angiographic result) to predict retreatment risk after endovascular therapy.

OBJECTIVE

To assess the external validity of the Aneurysm Recanalization Stratification Scale.

METHODS

External validity was assessed in independent cohorts from 4 centers in the United States and Canada where endovascular and open neurovascular procedures are performed, and in a multicenter cohort of 1543 patients. Probability of retreatment stratified by risk score was derived for each center and the combined multicenter cohort.

RESULTS

Despite moderate variability in retreatment rate among centers (29.5%, 9.9%, 9.6%, 26.3%, 19.7%, and 18.3%), the Aneurysm Recanalization Stratification Scale demonstrated good predictive value with C-statistics of 0.799, 0.943, 0.780, 0.695, 0.755, and 0.719 for each center and the combined cohort, respectively. Probability of retreatment stratified by risk score for the combined cohort is as follows: -2, 4.9%; -1, 5.7%; 0, 5.8%; 1, 13.1%; 2, 19.2%; 3, 34.9%; 4, 32.7%; 5, 73.2%; 6, 89.5%; and 7, 100.0%.

CONCLUSION

Surgical decision-making and patient-centered informed consent require comprehensive and accessible information on treatment efficacy. The Aneurysm Recanalization Stratification Scale is a valid prognostic index. This is the first comprehensive model that has been developed to quantitatively predict retreatment risk following endovascular therapy.

Intraoperative indocyanine green videoangiography to guide decision making regarding need for vessel bypass: A case report and technical note

Background:

Indocyanine green (ICG) videoangiography is an intraoperative technique recently used in vascular neurosurgery to assess the presence or absence of blood flow during critical times of a procedure. These include, but are not limited to, detecting whether daughter branches or perforators are patent after placing a vascular clip or determining whether an aneurysm has been completely isolated from the cerebral circulation after clipping. We present a case of a less-commonly reported application of ICG videoangiography involving the selection of a vessel to act as the bypass recipient once the need is identified during the surgical treatment of a complex intracranial aneurysm.

Case Description:

A 51-year-old male presented with a ruptured dissecting superior cerebellar artery (SCA) aneurysm that had two branches arising from the dome. Due to the difficult morphology of this aneurysm, a superficial temporal artery to SCA bypass was planned. We used ICG videoangiography to identify the branch that had insufficient retrograde flow via collateral circulation, to which the bypass was performed, followed by the isolation of the aneurysm from the cerebral circulation using permanent surgical clips.

Conclusion:

Our case represents a possible use of ICG videoangiography during the operative treatment of a difficult aneurysm. Our patient suffered no infarcts postoperatively. In the correct clinical context, this method represents a possible treatment option for complex aneurysms requiring a bypass.

Impacts from control operations on a recreationally hunted feral swine population at a large military installation in Florida

Feral swine were targeted for control at Avon Park Air Force Range in south-central Florida to avert damage to sensitive wetland habitats on the 40,000-ha base. We conducted a 5-year study to assess impacts from control to this population that had been recreationally hunted for many years. Control was initiated in early 2009. The feral swine population was monitored from 2008 to 2012 using a passive tracking index (PTI) during the dry and wet seasons and using recreational hunter take rates from the dry season. All three indices showed substantial feral swine declines after implementing control, with indices leveling for the final two study years. Military missions and recreational hunting seasons impacted temporal and spatial consistency of control application, thereby limiting further impacts of control efforts on the feral swine population. The PTI was also able to monitor coyotes, another invasive species on the base, and detect Florida black bear and Florida panther, species of particular concern.

Brainstem cavernoma hemorrhage during pregnancy in a 15-year-old: description of a unique neurosurgical approach

Cavernous haemangiomas, or cavernous malformations, have been reported during pregnancy, most of which have been either supratentorial or spinal lesions. We encountered a 15-year old pregnant patient with a rapidly progressive and haemorrhagic brainstem cavernous haemangioma. The case presented here describes the history and findings of this patient, as well as the less-commonly utilized technique we used to access the floor of the fourth ventricle via occipital craniotomy for complete macroscopic resection of this lesion, resulting in the gradual return of most of her neurological deficits.

Record of a Zoophthora sp. (Entomophthoromycota: Entomophthorales) pathogen of the irruptive noctuid moth Eurois occulta (Lepidoptera) in West Greenland

Eurois occulta undergoes extreme population fluctuations in Greenland, with long periods of low density punctuated by brief population explosions. During the summers of high E. occulta density in 2010 and 2011, large numbers of deceased late-instar larvae were observed in the summit disease position characteristic of entomophthoralean infection. Using genetic and morphological data, infected larvae from 2011 were determined to contain resting spores of a fungus of the genus Zoophthora, its first reported observation in the Arctic. In the absence of observation of primary spores or other identifying characters, a specific designation or description is not possible.

Central pontine and extrapontine myelinolysis in children: a review of 76 patients

This study aimed to identify the causes and contributing factors, neurologic presentation, and outcomes of central pontine and extrapontine myelinolysis and to examine any trends in the presentation and course of these disorders over the past 50 years. Seventy-six pediatric cases were identified in the literature. Age, sex, decade of diagnosis, neurologic presentation, outcome, and attributed causes were extracted. The results showed that the diagnosis, course, and outcomes of central pontine and extrapontine myelinolysis clearly have changed over the past few decades. Early cases generally were diagnosed at autopsy as opposed to computed tomography or magnetic resonance imaging more recently. Ninety-four percent of cases prior to 1990 and only 7% of cases from 1990 onward resulted in patient mortality. The decade in which the case was reported was the strongest predictor of outcome (P < .001), followed by sodium dysregulation (P = .045) and dehydration (P = .07).

The in Vitro Plasma Distribution of a Novel Cholesteryl Ester Transfer Protein Inhibitor, Torcetrapib, Is Influenced by Differences in Plasma Lipid Concentrations

PURPOSE

To determine the lipoprotein distribution of Torcetrapib in normolipidemic or hyperlipidemic human plasma and assess any changes in distribution due to lipid profile.

METHODS

Torcetrapib was incubated with human plasma samples, and the distribution was measured across four fractions: triglyceride-rich lipoprotein (TRL), low-density lipoprotein, high-density lipoprotein, and lipoprotein-deficient plasma fraction. Two stocks of human plasma were used, one considered normolipidemic (total cholesterol concentration = 164 mg/dL, triglycerides concentration = 139 mg/dL, protein concentration = 912 mg/dL), the other hyperlipidemic (total cholesterol = 260 mg/dL, triglycerides = 775 mg/dL, protein = 917 mg/dL). The plasma samples were incubated with Torcetrapib at 37 degrees C, and the incubation was stopped with the addition of sodium bromide and cooling to 4 degrees C. The plasma samples were then separated by density gradient ultracentrifugation to their lipoprotein fractions. The resulting lipoprotein fractions and an aliquot of incubated plasma were analyzed by a validated gas chromatography/tandem mass spectrometry analytical method. The distribution of Torcetrapib was determined first with varying incubation times, then with several concentrations.

RESULTS

At concentrations of 250 and 500 ng/mL, Torcetrapib distributed evenly across the four fractions in normolipidemic plasma. At the same concentrations in hyperlipidemic plasma, approximately 84% of Torcetrapib was found in the TRL fraction, with the remaining 16% evenly partitioned between the low-density lipoprotein, high-density lipoprotein, and lipoprotein-deficient plasma fractions.

CONCLUSIONS

The results suggest that lipid profile affects the distribution of Torcetrapib in hyperlipidemic human plasma lipoprotein fractions. The preferential distribution of Torcetrapib into the TRL fraction in hyperlipidemic plasma needs to be investigated to see if it will affect the pharmacological effect of Torcetrapib in vivo.

Differential effect of HERG blocking agents on cardiac electrical alternans in the guinea pig

Beat-to-beat alternations of the cardiac monophasic action potential, known as electrical alternans, were studied at drug concentrations that have known arrhythmogenic outcomes. Electrical alternans were elicited from the heart of anesthetized guinea pigs, both in the absence and presence of drugs that inhibit the delayed rectifier K(+) channel encoded by the human ether a-go-go related-gene (HERG), and are associated with the fatal arrhythmia, Torsade de Pointes. Two other HERG inhibiting drugs not associated with Torsade de Pointes were also studied. At concentrations known to be proarrhythmic, E-4031 and bepridil increased mean alternans 10 and 40 ms at pacing frequencies </=160 ms. Terfenadine and cisapride both increased mean alternans up to 20 and 21 ms, respectively, at pacing frequencies of </=150 ms. On the other hand, verapamil and risperidone showed no increase in mean alternans while risperidone significantly reduced alternans at concentrations up to 74 times its therapeutic level. The magnitude of effect on rate-dependent alternans may allow the differentiation of proarrhythmia and non-arrhythmic HERG blockers at clinically relevant concentrations.

Novel field sampling procedure for the determination of methiocarb residues in surface waters from rice fields

Methiocarb was extracted from surface water samples collected at experimental rice field sites in Louisiana and Texas. The sampling system consisted of a single-stage 90-mm Empore extraction disk unit equipped with a battery-powered vacuum pump. After extraction, the C-18 extraction disks were stored in an inert atmosphere at -10 degrees C and shipped overnight to the laboratory. The disks were extracted with methanol and the extracts analyzed by reversed-phase high-performance liquid chromatography with a methanol/water mobile phase. Methiocarb was detected by ultraviolet absorption at 223 nm and quantified with the use of calibration standards. Recoveries from control surface water samples fortified at 5.0, 10, 50, and 100 ng/mL methiocarb averaged 92 +/- 7%. A method limit of detection for methiocarb in rice field surface water was estimated to be 0.23 ng/mL at 223 nm.

Technology-enhanced distance education: from experimentation to concerted action

Despite the rush to embrace technology-enhanced learning (TEL), descriptions of how schools of nursing move toward systemwide implementation of this type of teaching are scarce. There is a wide gap between sporadic dabbling by individual instructors in specific courses and adoption and implementation of TEL throughout a program. This article describes the experiences of a group of nursing faculty who helped move one school of nursing from experimentation with TEL in distance education to concerted action toward a strategic schoolwide plan. J Prof Nurs 17:135-140, 2001.

Improving the selectivity of HAV-peptides in modulating E-cadherin-E-cadherin interactions in the intercellular junction of MDCK cell monolayers

PURPOSE

The objective of this work is to understand the sequence specificity of HAV peptides and to improve their selectivity in regulating E-cadherin-E-cadherin interactions in the intercellular junctions.

METHODS

Peptide 1 was modified using an alanine scanning method to give peptides 2-6. The ability of these peptides to modulate intercellular junctions was evaluated using Madin-Darby Canine Kidney (MDCK) cell monolayers on Transwell membranes from either the apical (AP) or the basolateral (BL) side. Modulation of the intercellular junctions was measured by the ability to lower the transepithelial electrical resistance (TEER) of MDCK monolayers and by the increase in mannitol flux. Molecular docking experiments were performed to model the binding properties of these peptides to the EC1 domain of E-cadherin.

RESULTS

Peptides 5 (Ac-SHAVAS-NH2) and 6 (Ac-SHAVSA-NH2) were found to be more effective than the parent peptide 1 in decreasing the resistance of the cell monolayer. Furthermore, comparative studies with the control and the weak inhibitor peptide 2 indicate that peptide 5 displayed a significant increase in mannitol flux. Molecular docking of peptides 1, 2 and 5 to the EC1 domain suggests that peptide 5 has the lowest binding energy.

CONCLUSIONS

HAV peptides have the ability to modulate E-cadherin-E-cadherin interactions in the intercellular junctions of the MDCK cell monolayer, thus indirectly increasing the permeability of the tight junctions. This observation indicates that residues flanking the HAV sequence are important in the binding selectivity of HAV peptides to E-cadherin. Molecular docking can further aid in the design of peptides with better selectivity to the EC1 domain of E-cadherin.

Functional expression of P-glycoprotein in primary cultures of human cytotrophoblasts and BeWo cells

The objective of this study was to investigate the functional expression of the efflux transporter, P-glycoprotein (P-gp), in primary cultures of human cytotrophoblasts and BeWo cell monolayers. Uptake studies with primary cultures of human cytotrophoblasts or BeWo cells were conducted with calcein-AM and vinblastine (P-gp markers) or fluorescein (MRP marker) in the presence of specific P-gp or MRP inhibitors. Results showed that the accumulation of P-gp substrates calcein-AM and vinblastine by BeWo cells or primary cultures of human cytotrophoblasts was significantly enhanced in the presence of a typical P-gp inhibitor, cyclosporin-A, or other inhibitors such as quinidine, verapamil, and dipyridamole. MRP inhibitors had no effect on the accumulation of calcein or fluorescein by BeWo cells. Western blots confirmed the presence of multidrug resistant gene product 1 (MDR1) in both primary cultures of human cytotrophoblasts and BeWo cells. This study demonstrates functional P-gp in term human trophoblasts and further supports the use of primary cultures of human cytotrophoblasts and BeWo cells as in vitro models of the trophoblast to investigate mechanisms regulating drug distribution across the placenta.

A theory of planned behavior-based structural model for breast-feeding

BACKGROUND

Breast-feeding is the recommended method of infant feeding because it is clearly associated with health benefits for infants and their mothers. Yet, many women who initiate breast-feeding fail to meet their own personal goals or recommended standards for duration of breast-feeding.

OBJECTIVE

To refine a Theory of Planned Behavior (TPB)-based structural model for explaining variability in breast-feeding intention and duration.

METHOD

The study design was prospective, multicorrelational, and longitudinal. Out of the total sample of 635 women, 602 mothers of healthy, full-term infants provided complete datasets over the entire course of their breast-feeding experience and these datasets were used in the modeling analyses. Simultaneous multisample analysis of covariance structures was used to develop the model.

RESULTS

The resulting TPB for Breast-Feeding (TPB-BrF) describes the rational, motivational processes of the original TPB, but reconfigures the relationships among them, for homemakers (TPB-BrF/H), women employed half-time or less (TPB-BrF/EL), and women employed more than half-time (TPB-BrF/EM). Mothers' early postpartum ratings of adequacy of milk supply and stimulus conditions of maternal education and breast-feeding knowledge were included in the TPB-BrF to better explain breast-feeding outcomes. Model complexity increased with employment effort.

CONCLUSION

The TPB-BrF is a comprehensive, theoretically based, empirically verified model that can serve as a useful heuristic for understanding the personal motivational components of breast-feeding behavior.

Factors associated with very early weaning among primiparas intending to breastfeed

OBJECTIVES

The major objective of this study was to identify predictor variables that accurately differentiated breastfeeding women who weaned during the first 4 weeks, those who weaned between 5 and 26 weeks, and those who weaned after 26 weeks. Predictors were demographic variables, Theory of Planned Behavior (TPB) variables, breastfeeding knowledge, and difficulties experienced during the first month.

METHODS

Primiparas who delivered healthy infants in an urban midwestern hospital provided initial data prior to discharge. Follow-up occurred at 1, 3, 6, 9, and 12 months. Following appropriate bivariate analyses, polychotomous logistic regression was used to determine predictors of weaning group. Linear multiple regression was used to predict intended duration.

RESULTS

Most of the 84 women who weaned very early had intended to breastfeed considerably longer. According to the multivariate analysis, women who weaned earlier were younger, had completed fewer years of education, had a more positive bottle-feeding attitude and a less positive breastfeeding attitude, intended to breastfeed less time, had lower knowledge scores, had higher perceived insufficient milk scores, and planned to work outside the home. Variables postulated by the TPB to be direct predictors of intention explained 36% of the variance in intended duration.

CONCLUSIONS

Women at risk for early weaning can be identified with reasonable accuracy using a TPB-based conceptual framework expanded to include breastfeeding specific variables. Casefinding using empirically derived screening methods and careful postpartum follow-up, along with professional intervention, should be used to avert unintended early weaning.

Permeability and metabolic properties of a trophoblast cell line (HRP-1) derived from normal rat placenta

The HRP-1 cell line is derived from normal rat placenta and appears morphologically similar to and retains characteristic expression of cellular markers of labyrinthine trophoblast cells. In this study, monolayers of HRP-1 cells grown on permeable supports were evaluated as a potential in vitro system to study trophoblast transport and metabolism. The cell line was shown to express and retain functional activity of the predominant placental cytochrome P450 isozyme, CYP1A1. Additionally, the HRP-1 cells retain functional activity of angiotensin I converting enzyme and carboxypeptidase N-like enzyme, peptidases characteristic of the trophoblast. The permeation of several hydrophilic, inert markers across the HRP-1 monolayers was observed to be dependent on effective molecular size and to be passive in nature. Functional asymmetry of the HRP-1 cells was illustrated by the predominant permeation of linoleic acid in the apical-to-basolateral direction across the monolayers. Transferrin passage across HRP-1 monolayers was concentration-dependent, was bidirectional, and could be inhibited by unlabeled transferrin, features typical of the trophoblast transport system for transferrin. Collectively, these properties suggest that the HRP-1 cell line may provide a useful tool for evaluating some of the permeability and metabolic properties of the trophoblast.

Sentinel lymph node metastasis in experimental melanoma: relationships among primary tumor size, lymphatic vessel diameter and 99mTc-labeled human serum albumin clearance

BACKGROUND

This study was designed to investigate the relationships among primary tumor size, lymphatic vessel diameters, the incidence of sentinel lymph node (SLN) metastasis and lymphatic clearance from murine footpad melanomas.

METHODS

Lymphatic clearance (LC) of [99mTc]HSA from the middle of the footpad of syngeneic C57BL/6 mice, with or without primary melanomas (sizes varying from 1 to 5 mm in anteroposterior diameter), was quantitated using a gamma scintillation detection system. Lymphatic vessel diameters (LD) were measured after injection of aniline blue dye into footpad tumors. The incidence of SLN, femoral lymph node (FLN), and lung metastases was recorded.

RESULTS

Metastasis to SLNs increased as tumor growth progressed (r = 0.976, p = 0.001), and there was a correlation between tumor size and both FLN (p = 0.041) and lung (p = 0.055) metastases. There was also a correlation between lymph node metastasis and LC (r = 0.83, p = 0.04) and LD (r = 0.84, p = 0.04).

CONCLUSIONS

These studies support the hypothesis that lymph flow and LD is increased in experimental murine melanomas and this relates to both primary tumor size and to lymphatic and hematogenous metastasis.

Lymphatic diameters and radionuclide clearance in a murine melanoma model

OBJECTIVES

To determine the clearance of a radionuclide from various sizes of footpad melanomas via lymphatics and to measure the diameters of these vessels.

DESIGN

Nonrandomized animal study.

SETTING

A hospital research laboratory.

SUBJECTS

C57BL/6 mice.

INTERVENTIONS

Female mice were injected in the right rear footpad with B16 F10 cells that were allowed to grow to either 1, 2, 3, 4, or 5 mm in anteroposterior diameter. Clearance from feet with or without tumors of injected technetium Tc 99m human serum albumin (99mTcHSA) was assessed for 200 minutes. Calf lymphatic diameters were measured using aniline blue dye.

RESULTS

The clearance of the injected 99mTcHSA from mouse footpads without tumors was 1.26 +/- 0.18 x 10(-4) mL/min x cm3 of tissue. Clearance increased 2.24-fold to 2.82 +/- 0.12 x 10(-4) mL/min x cm3 of tissue from 1-mm tumors and to 6.20 +/- 0.08, 6.11 +/- 0.13, 6.91 +/- 0.58, and 7.23 +/- 0.48 x 10(-4) mL/min x cm3 of tissue from 2-, 3-, 4-, and 5-mm tumors, respectively (P < .05). Calf lymphatic diameters increased from 75.41 +/- 9.72 microns in naive nontumor-bearing mice to 93.51 +/- 7.12, 111.61 +/- 27.07, 126.69 +/- 25.20, 124.43 +/- 24.75, and 127.44 +/- 25.35 microns in mice bearing 1-, 2-, 3-, 4-, and 5-mm tumors, respectively (P < .01).

CONCLUSIONS

There was a size-dependent, direct correlation between increasing tumor size in the footpad and increasing diameter of lymphatics draining the footpad. Clearance of injected 99mTcHSA from these tumors also exhibited a similar positive correlation with tumor size.