Mechanical properties of l-lysine based segmented polyurethane vascular grafts and their shape memory potential.

Segmented polyurethanes based on polycaprolactone, 4,4 (metylene-bis-cyclohexyl) isocyanate, and l-lysine were synthesized, manufactured as small vascular grafts and characterized according to ISO 7198 standard for cardiovascular implants-tubular vascular prosthesis. In terms of mechanical properties, the newly synthesized polyurethane films exhibited lower secant modulus than Tecoflex™ SG 80A, a well-known medical grade polyurethane. Similarly, when tested as grafts, the l-lysine-based polyurethane exhibited lower longitudinal failure load (11.5 N vs. 116 N), lower circumferential failure load per unit length (5.67 N/mm vs. 14.0 N/mm) and lower suture forces for both nylon (13.3 N vs. 24.0 N) and silk (14.0 N vs. 19.3 N) when compared to Tecoflex™ SG 80A grafts. l-Lysine-based graft exhibited a burst strength of 3620 mmHg (482.6 kPa) and a compliance of 0.16%/mmHg. The cell adhesion was demonstrated with NIH/3T3 fibroblasts where cell adhesion was observed on both films and grafts, while cell alignment was observed only on the grafts. The mechanical properties of this polyurethane and the possibility of strain-induced PCL crystals as the switching phase for shape memory materials, allowed a strain recovery ratio and a strain fixity ratio with values higher than 95% and 90%, respectively, with a repeatability of the shape-memory properties up to 4 thermo-mechanical cycles. Overall, the properties of lysine-based polyurethanes are suitable for large diameter vascular grafts where cell alignment can be controlled by their shape memory potential.

High levels of LDL-C combined with low levels of HDL-C further increase platelet activation in hypercholesterolemic patients

High levels of low-density lipoprotein cholesterol (LDL-C) enhance platelet activation, whereas high levels of high-density lipoprotein cholesterol (HDL-C) exert a cardioprotective effect. However, the effects on platelet activation of high levels of LDL-C combined with low levels of HDL-C (HLC) have not yet been reported. We aimed to evaluate the platelet activation marker of HLC patients and investigate the antiplatelet effect of atorvastatin on this population. Forty-eight patients with high levels of LDL-C were enrolled. Among these, 23 had HLC and the other 25 had high levels of LDL-C combined with normal levels of HDL-C (HNC). A total of 35 normocholesterolemic (NOMC) volunteers were included as controls. Whole blood flow cytometry and platelet aggregation measurements were performed on all participants to detect the following platelet activation markers: CD62p (P-selectin), PAC-1 (GPIIb/IIIa), and maximal platelet aggregation (MPAG). A daily dose of 20 mg atorvastatin was administered to patients with high levels of LDL-C, and the above assessments were obtained at baseline and after 1 and 2 months of treatment. The expression of platelets CD62p and PAC-1 was increased in HNC patients compared to NOMC volunteers (P<0.01 and P<0.05). Furthermore, the surface expression of platelets CD62p and PAC-1 was greater among HLC patients than among HNC patients (P<0.01 and P<0.05). Although the expression of CD62p and PAC-1 decreased significantly after atorvastatin treatment, it remained higher in the HLC group than in the HNC group (P<0.05 and P=0.116). The reduction of HDL-C further increased platelet activation in patients with high levels of LDL-C. Platelet activation remained higher among HLC patients regardless of atorvastatin treatment.

High levels of LDL-C combined with low levels of HDL-C further increase platelet activation in hypercholesterolemic patients.

High levels of low-density lipoprotein cholesterol (LDL-C) enhance platelet activation, whereas high levels of high-density lipoprotein cholesterol (HDL-C) exert a cardioprotective effect. However, the effects on platelet activation of high levels of LDL-C combined with low levels of HDL-C (HLC) have not yet been reported. We aimed to evaluate the platelet activation marker of HLC patients and investigate the antiplatelet effect of atorvastatin on this population. Forty-eight patients with high levels of LDL-C were enrolled. Among these, 23 had HLC and the other 25 had high levels of LDL-C combined with normal levels of HDL-C (HNC). A total of 35 normocholesterolemic (NOMC) volunteers were included as controls. Whole blood flow cytometry and platelet aggregation measurements were performed on all participants to detect the following platelet activation markers: CD62p (P-selectin), PAC-1 (GPIIb/IIIa), and maximal platelet aggregation (MPAG). A daily dose of 20 mg atorvastatin was administered to patients with high levels of LDL-C, and the above assessments were obtained at baseline and after 1 and 2 months of treatment. The expression of platelets CD62p and PAC-1 was increased in HNC patients compared to NOMC volunteers (P<0.01 and P<0.05). Furthermore, the surface expression of platelets CD62p and PAC-1 was greater among HLC patients than among HNC patients (P<0.01 and P<0.05). Although the expression of CD62p and PAC-1 decreased significantly after atorvastatin treatment, it remained higher in the HLC group than in the HNC group (P<0.05 and P=0.116). The reduction of HDL-C further increased platelet activation in patients with high levels of LDL-C. Platelet activation remained higher among HLC patients regardless of atorvastatin treatment.

Physicochemical characterization of segmented polyurethanes prepared with glutamine or ascorbic acid as chain extenders and their hydroxyapatite composites.

The development of elastomeric, bioresorbable, and biocompatible segmented polyurethanes (SPUs) for use in tissue-engineering applications has attracted considerable interest in recent years because of the existing need for mechanically tunable scaffolds for regeneration of different tissues. In this study segmented polyurethanes were synthesized from poly(ε-caprolactone)diol, 4,4'-methylene bis(cyclohexyl isocyanate) (HMDI) using osteogenic compounds such as ascorbic acid (AA) and l-glutamine (GL) as chain extenders, which are known to play a role in osteoblast proliferation and collagen synthesis. Fourier transform infrared spectroscopy (FTIR) revealed the formation of urethane linkages at 3373, 1729, and 1522 cm-1 (N-H stretching, C[double bond, length as m-dash]O stretching and N-H bending + C-N stretching vibrations, respectively) while urea formation was confirmed by the appearance of a peak at 1632 cm-1. Differential scanning calorimetry, dynamic mechanical analysis, X-ray diffraction and mechanical testing of the polyurethanes showed that these polyurethanes were semi-crystalline polymers (Tg = -25 °C; Tm = 51.4-53.8 °C; 2θ = 21.3° and 23.4°) exhibiting elastomeric behavior (ε > 1000%) only for those prepared by HA incorporation during prepolymer formation. Dense and porous composite matrices of the segmented polyurethanes were prepared by the addition of hydroxyapatite (HA) via either mechanical mixing or in situ polymerization and supercritical fluid processing, respectively. The addition of HA by physical mixing decreased the crystallinity (from 38% to 31%) of the composites prepared with ascorbic acid as the chain extender. Both Tg of the composites and the strain were also lowered to -38 or 36 °C and 27-39% for ascorbic acid and glutamine containing polyurethanes respectively. Composites prepared with ascorbic acid as the chain extender yielded higher Young's modulus and tensile strength than composites prepared with glutamine when HA was incorporated during prepolymer formation. Composites obtained by incorporation of HA by physical mixing revealed a poor dispersion in comparison to composites obtained via HA inclusion during prepolymer formation. In contrast, good dispersion of HA and porosity were achieved at 60 °C, 400 bar and holding times between 0.5 h and 2 h with a downtime between 15 min and 60 min in the CO2 reactor. Biocompatibility studies showed that SPUs containing ascorbic acid allowed the increase of alveolar osteoblast proliferation; hence, they are potentially suitable for bone tissue regeneration.

HUVEC biocompatibility and platelet activation of segmented polyurethanes prepared with either glutathione or its amino acids as chain extenders.

Novel biodegradable segmented polyurethanes (SPUs) were synthesized with polycaprolactone diol, 4,4'-methylen bis (cyclohexyl isocyanate) (HMDI), and either L-glutathione or its constituent amino acids (L-glutamic acid, L-cysteine and glycine) as chain extenders. Fourier transform infrared spectroscopy analysis revealed the feasibility of obtaining polyurethanes through the presence of NH (Amide II), C-N, C-O, and C=O bands and the absence of NCO band. Differential scanning calorimetry and X-ray diffraction revealed that a semicrystalline polymer (T m = 42-52 °C; 2θ = 21.3° and 23°) was obtained in all cases, while dynamic mechanical analysis (DMA) revealed an amorphous phase (T g = -30 to -36 (o)C). These properties, in addition to their high molecular weight, led to high moduli and higher extensibilities when glycine and glutamic acid were used as chain extenders. Clotting times (Lee-White test) and activated partial thromboplastin time determined on these polyurethanes were longer than with glass. In addition, all synthesized SPU exhibited platelet activation indexes below the collagen type I positive control. Human umbilical vein endothelial cells viability was higher in SPUs containing either glycine or cysteine. The obtained results indicate that SPUs that use cysteine as chain extender are promising candidates for cardiovascular applications.

Characterization and biocompatibility studies of new degradable poly(urea)urethanes prepared with arginine, glycine or aspartic acid as chain extenders.

Polyurethanes are very often used in the cardiovascular field due to their tunable physicochemical properties and acceptable hemocompatibility although they suffer from poor endothelialization. With this in mind, we proposed the synthesis of a family of degradable segmented poly(urea)urethanes (SPUUs) using amino acids (L-arginine, glycine and L-aspartic acid) as chain extenders. These polymers degraded slowly in PBS (pH 7.4) after 24 weeks via a gradual decrease in molecular weight. In contrast, accelerated degradation showed higher mass loss under acidic, alkaline and oxidative media. MTT tests on polyurethanes with L-arginine as chain extenders showed no adverse effect on the metabolism of human umbilical vein endothelial cells (HUVECs) indicating the leachables did not provoke any toxic responses. In addition, SPUUs containing L-arginine promoted higher levels of HUVECs adhesion, spreading and viability after 7 days compared to the commonly used Tecoflex(®) polyurethane. The biodegradability and HUVEC proliferation on L-arginine-based SPUUs suggests that they can be used in the design of vascular grafts for tissue engineering.

Characterization of Bone Cements Prepared with Either Hydroxyapatite, α-TCP or Bovine Bone / Caracterización de cementos óseos preparados con hidroxiapatita, α-TCP o hueso bovino

In this work, we report the preparation of bone cements by using methyl methacrylate (MMA) as a base monomer and either hydroxyapatite (HA), alpha tricalcium phosphate (α-TCP) or bovine bone particles as bioactive fillers. In general, it was observed that curing times increased by the addition of any of these fillers (from 4 to 6.7 min). Maximum temperatures decrease slightly by the addition of 20 wt.% of either α-TCP or bovine bone (80.3°C and 73.2°C respectively) but it did not change by the addition of HA (84.3°C) with respect to PMMA only bone cement used as control. Residual monomer content was lower than 4% in the bioactive bone cements. By using α-TCP or bovine bone compressive strength increased with respect to the unfilled bone cement but it was reduced when HA was used. However, all these formulations fulfill the 70 MPa required for bone cement use. Flexural strength was increased by using either a-TCP o bovine bone but the addition of HA decreased this properties compared to the base bone cement. However, the minimum flexural strength (50 MPa) was fulfilled only in those experimental formulations containing low amounts of α-TCP. The minimum tensile strength (30 MPa) was satisfied by all formulations but it was always lower than the exhibited by the unfilled bone cement.

Este trabajo reporta la preparación de cementos óseos utilizando metacrilato de metilo (MMA) como monómero base y rellenos bioactivos tales como hidroxiapatita (HA), fosfato tricálcico alfa (α-TCP) o hueso bovino. En general, los tiempos de curado aumentaron con la inclusión de estos refuerzos (de 4 hasta 6.7 min). La temperatura máxima alcanzada durante la polimerización del cemento disminuyó ligeramente al adicionar 20% de α-TCP o hueso bovino (80.3°C y 73.2°C respectivamente) y se mantuvo sin cambio en las formulaciones con HA (84.3°C) con respecto al control de solo PMMA. El contenido de monómero residual en los cementos bioactivos fue menor al 4%. La presencia de α-TCP o hueso bovino aumentó la resistencia a la compresión del cemento base y la adición de HA la disminuyó, cumpliendo en todos los casos con la resistencia mínima a la compresión (70 MPa) sugerida para su uso como cemento óseo. La adición de α-TCP o hueso bovino aumentó la resistencia a la flexión del cemento base pero la adición de HA la redujo aunque el requerimiento mínimo de resistencia a la flexión (50 MPa) fue cumplido solamente al usar concentraciones bajas de α-TCP. La resistencia tensil mínima (30 MPa) fue satisfecha por todas las formulaciones aunque siempre fue menor que la exhibida por el cemento base.

Effects of abiotic stress on biomass and anthocyanin production in cell cultures of Melastoma malabathricum.

Plant cell cultures could be used as an important tool for biochemical production, ranging from natural coloring (pigments) to pharmaceutical products. Anthocyanins are becoming a very important alternative to synthetic dyes because of increased public concern over the safety of artificial food coloring agents. Several factors are responsible for the production of anthocyanin in cell cultures. In the present study, we investigate the effects of different environmental factors, such as light intensity, irradiance (continuous irradiance or continuous darkness), temperature and medium pH on cell biomass yield and anthocyanin production in cultures of Melastoma malabathricum. Moderate light intensity (301 - 600 lux) induced higher accumulation of anthocyanins in the cells. The cultures exposed to 10-d continuous darkness showed the lowest pigment content, while the cultures exposed to 10-d continuous irradiance showed the highest pigment content. The cell cultures incubated at a lower temperature range (20 ± 2 ºC) grew better and had higher pigment content than those grown at 26 ± 2 ºC and 29 ± 2 ºC. Different medium pH did not affect the yield of cell biomass but anthocyanin accumulation was highest at pH 5.25 - 6.25.

Degradation studies on segmented polyurethanes prepared with HMDI, PCL and different chain extenders.

Biodegradable segmented polyurethanes (BSPUs) were prepared with poly(caprolactone) as a soft segment, 4,4'-methylene bis (cyclohexyl isocyanate) and either butanediol (BSPU1) or dithioerythritol (BSPU2) as a chain extender. BSPU samples were characterized in terms of their physicochemical properties and their hemocompatibility. Polymers were then degraded in acidic (HCl 2N), alkaline (NaOH 5M) and oxidative (H(2)O(2) 30wt.%) media and characterized by their mass loss, Fourier transform infrared (FTIR), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), X-ray diffraction (XRD) and scanning electron microscopy (SEM). Undegraded BSPU1 and BSPU2 exhibited different properties, such as the glass transition temperature T(g) of the soft segment (-25 vs. 4 degrees C), mechanical properties (600% vs. 900% strain to break) and blood coagulating properties (clotting time=11.46 vs. 8.13min). After acidic and alkaline degradation, the disappearance of the 1728cm(-1) band of polycaprolactone (PCL) on both types of BSPU was detected by FTIR. However, the oxidative environment did not affect the soft segment severely as the presence of PCL crystalline domains were observed both by DSC (melting temperature T(m)=52.8 degrees C) and XRD (2theta=21.3 degrees and 23.7 degrees ). By TGA three decomposition temperatures were recorded for both BSPU samples, but the higher decomposition temperature was enhanced after acidic and alkaline degradation. The formation of the porous structure on BSPU1 was observed by SEM, while a granular surface was observed on BSPU2 after alkaline degradation.

Effects of abiotic stress on biomass and anthocyanin production in cell cultures of Melastoma malabathricum

Plant cell cultures could be used as an important tool for biochemical production, ranging from natural coloring (pigments) to pharmaceutical products. Anthocyanins are becoming a very important alternative to synthetic dyes because of increased public concern over the safety of artificial food coloring agents. Several factors are responsible for the production of anthocynin in cell cultures. In the present study, we investigate the effects of different environmental factors, such as light intensity, irradiance (continuous irradiance or continuous darkness), temperature and medium pH on cell biomass yield and anthocyanin production in cultures of Melastoma malabathricum. Moderate light intensity (301 - 600 lux) induced higher accumulation of anthocyanins in the cells. The cultures exposed to 10-d continuous darkness showed the lowest pigment content, while the cultures exposed to 10-d continuous irradiance showed the highest pigment content. The cell cultures incubated at a lower temperature range (20 ± 2 ºC) grew better and had higher pigment content than those grown at 26 ± 2ºC and 29 ± 2ºC. Different medium pH did not affect the yield of cell biomass but anthocyanin accumulation was highest at pH 5.25 - 6.25.

17-year follow-up of a randomized prospective controlled trial of adjuvant intravesical doxorubicin in the treatment of superficial bladder cancer.

PURPOSE: To evaluate the efficacy of adjuvant intravesical doxorubicin in superficial transitional cell carcinoma of the urinary bladder on long-term follow-up. MATERIALS AND METHODS: Between July 1986 and November 1991, all patients harboring superficial bladder cancers (Ta or T1) with one or more of these criteria (stage>a, grade>1, size>1 cm, multiple or recurrent tumors) were randomized to receive either 50 mg doxorubicin or no adjuvant therapy. Patients with recurrences were allowed to receive doxorubicin or other intravesical agents. Recurrence, progression and survival were analyzed. RESULTS: There were 82 patients included (64 males and 18 females). The mean age was 64 years. Forty-six patients were randomized to the doxorubicin group and 36 to the control group. Final analysis was made at median follow-up of 45, 128 and 131.5 months for recurrence, progression and survival, respectively. Recurrence free, progression free and disease specific survival did not differ significantly between groups. The 10-year Kaplan-Meier estimates for recurrence free, progression free and disease specific survival were 67%, 84% and 92%, respectively for the doxorubicin group, and were 50%, 89% and 97%, respectively for the control group. Tumor size predicted recurrence (p=0.013) and grade predicted progression (p=0.004) with multivariate analysis. CONCLUSIONS: Adjuvant intravesical doxorubicin could not be shown to improve recurrence, progression and survival of superficial bladder cancer, compared with control on long-term follow-up. Tumor size and grade were shown to be prognostic factors for recurrence and progression, respectively.

17-year follow-up of a randomized prospective controlled trial of adjuvant intravesical doxorubicin in the treatment of superficial bladder cancer

PURPOSE: To evaluate the efficacy of adjuvant intravesical doxorubicin in superficial transitional cell carcinoma of the urinary bladder on long-term follow-up. MATERIALS AND METHODS: Between July 1986 and November 1991, all patients harboring superficial bladder cancers (Ta or T1) with one or more of these criteria (stage > a, grade > 1, size > 1 cm, multiple or recurrent tumors) were randomized to receive either 50 mg doxorubicin or no adjuvant therapy. Patients with recurrences were allowed to receive doxorubicin or other intravesical agents. Recurrence, progression and survival were analyzed. RESULTS: There were 82 patients included (64 males and 18 females). The mean age was 64 years. Forty-six patients were randomized to the doxorubicin group and 36 to the control group. Final analysis was made at median follow-up of 45, 128 and 131.5 months for recurrence, progression and survival, respectively. Recurrence free, progression free and disease specific survival did not differ significantly between groups. The 10-year Kaplan-Meier estimates for recurrence free, progression free and disease specific survival were 67 percent, 84 percent and 92 percent, respectively for the doxorubicin group, and were 50 percent, 89 percent and 97 percent, respectively for the control group. Tumor size predicted recurrence (p = 0.013) and grade predicted progression (p = 0.004) with multivariate analysis. CONCLUSIONS: Adjuvant intravesical doxorubicin could not be shown to improve recurrence, progression and survival of superficial bladder cancer, compared with control on long-term follow-up. Tumor size and grade were shown to be prognostic factors for recurrence and progression, respectively.

Prediction of differential creatinine clearance in chronically obstructed kidneys by non-contrast helical computerized tomography

PURPOSE: We investigate the use of non-contrast helical computerized tomography (NCHCT) in the measurement of differential renal parenchymal volume as a surrogate for differential creatinine clearance (CrCl) for unilateral chronically obstructed kidney. MATERIALS AND METHODS: Patients with unilateral chronically obstructed kidneys with normal contralateral kidneys were enrolled. Ultrasonography (USG) of the kidneys was first done with the cortical thickness of the site with the most renal substance in the upper pole, mid-kidney, and lower pole of both kidneys were measured, and the mean cortical thickness of each kidney was calculated. NCHCT was subsequently performed for each patient. The CT images were individually reviewed with the area of renal parenchyma measured for each kidney. Then the volume of the slices was summated to give the renal parenchymal volume of both the obstructed and normal kidneys. Finally, a percutaneous nephrostomy (PCN) was inserted to the obstructed kidney, and CrCl of both the obstructed kidney (PCN urine) and the normal side (voided urine) were measured two 2 after the relief of obstruction. RESULTS: From March 1999 to February 2001, thirty patients were enrolled into the study. Ninety percent of them had ureteral calculi. The differential CrCl of the obstructed kidney ( percentCrCl) was defined as the percentage of CrCl of the obstructed kidney as of the total CrCl, measured 2 weeks after relief of obstruction. The differential renal parenchymal volume of the obstructed kidney ( percentCTvol) was the percentage of renal parenchymal volume as of the total parenchymal volume. The differential USG cortical thickness of the obstructed kidney ( percentUSGcort) was the percentage of mean cortical thickness as of the total mean cortical thickness. The Pearson's correlation coefficient (r) between percentCTvol and percentCrCl and that between percentUSGcort and percentCrCl were 0.756 and 0.543 respectively. The regression line was percentCrCl = (1.00) x percentCTvol - 14.27. The percentCTvol overestimated the differential creatinine clearance by about 14 percent, but the correlation is good. CONCLUSION: The differential renal parenchymal volume measured by NCHCT provided a reasonable prediction of differential creatinine clearance in chronically obstructed kidneys.

Prediction of differential creatinine clearance in chronically obstructed kidneys by non-contrast helical computerized tomography.

PURPOSE: We investigate the use of non-contrast helical computerized tomography (NCHCT) in the measurement of differential renal parenchymal volume as a surrogate for differential creatinine clearance (CrCl) for unilateral chronically obstructed kidney. MATERIALS AND METHODS: Patients with unilateral chronically obstructed kidneys with normal contralateral kidneys were enrolled. Ultrasonography (USG) of the kidneys was first done with the cortical thickness of the site with the most renal substance in the upper pole, mid-kidney, and lower pole of both kidneys were measured, and the mean cortical thickness of each kidney was calculated. NCHCT was subsequently performed for each patient. The CT images were individually reviewed with the area of renal parenchyma measured for each kidney. Then the volume of the slices was summated to give the renal parenchymal volume of both the obstructed and normal kidneys. Finally, a percutaneous nephrostomy (PCN) was inserted to the obstructed kidney, and CrCl of both the obstructed kidney (PCN urine) and the normal side (voided urine) were measured two 2 after the relief of obstruction. RESULTS: From March 1999 to February 2001, thirty patients were enrolled into the study. Ninety percent of them had ureteral calculi. The differential CrCl of the obstructed kidney (%CrCl) was defined as the percentage of CrCl of the obstructed kidney as of the total CrCl, measured 2 weeks after relief of obstruction. The differential renal parenchymal volume of the obstructed kidney (%CTvol) was the percentage of renal parenchymal volume as of the total parenchymal volume. The differential USG cortical thickness of the obstructed kidney (%USGcort) was the percentage of mean cortical thickness as of the total mean cortical thickness. The Pearson's correlation coefficient (r) between %CTvol and %CrCl and that between %USGcort and %CrCl were 0.756 and 0.543 respectively. The regression line was %CrCl = (1.00) x %CTvol - 14.27. The %CTvol overestimated the differential creatinine clearance by about 14%, but the correlation is good. CONCLUSION: The differential renal parenchymal volume measured by NCHCT provided a reasonable prediction of differential creatinine clearance in chronically obstructed kidneys.

Comparison of skin stapling devices and standard sutures for pediatric scalp lacerations: a randomized study of cost and time benefits.

OBJECTIVE: To compare the total costs and the physician time requirements for suture and staple repair of pediatric scalp lacerations. STUDY DESIGN: Eighty-eight children, 13 months to 16 years of age, coming to a children's hospital emergency department with simple scalp lacerations were prospectively randomly selected to receive staple or suture repair. Wound lengths, times required for initial wound care and closure, and equipment use were recorded. Patients returned in 1 week for suture or staple removal and wound reevaluation. The two methods were compared in terms of both time expended and costs of equipment and physician compensation. RESULTS: Forty-five children underwent staple repair and 43 underwent suture repair. There were no differences in age, sex, wound length, number of sutures or staples per centimeter, or physician experience. Stapling resulted in shorter wound closure times (65 vs 397 seconds; p < 0.0001) and shorter overall times for wound care and closure (395 vs 752 seconds; p < 0.0001). Staple repair was less expensive in terms of equipment ($12.55 vs $17.59; p < 0.0001) and total cost based on equipment and physician time ($23.55 vs $38.51; p < 0.0001). The follow-up rate was 91%, with no cosmetic or infectious complications in either group. CONCLUSIONS: Stapling is faster and less expensive than suturing in the repair of uncomplicated pediatric scalp lacerations, with no additional complications. Physicians who treat children with scalp lacerations should consider the use of stapling devices.

Immune responsiveness to the immunodominant recombinant envelope epitopes of human T lymphotropic virus types I and II in diverse geographic populations.

The heterogeneity of immune responsiveness to the immunodominant epitopes of human T lymphotropic virus (HTLV) types I (MTA-1(162-209)) and II (K-55(162-205)) were determined in natural infections with HTLV-I and -II from diverse geographic areas (n = 285). Of the HTLV-I specimens confirmed by polymerase chain reaction (PCR), all North American (n = 37) and Peruvian (n = 19) specimens reacted with MTA-1. Of HTLV-II specimens confirmed by PCR, 44 (96%) of 46 from North American blood donors, 28 (97%) of 29 from native Americans, and all from intravenous drug users (n = 29) reacted with K-55. Specimens from other geographic areas (Peru, 30; Brazil, 4; Mexico, 10; Italy, 5; Somalia, 13; Ethiopia, 17; Japan, 32; and Jamaica, 15) all reacted either with MTA-1 or K-55. By synthetic peptide-based serologic typing, all of these specimens could be typed as HTLV-I or -II. In addition to the direct implications of these findings for diagnostic purposes, these data provide indirect evidence for the conservation of immunodominant HTLVenv epitopes in diverse geographic populations.

Segregation of human T cell lymphotropic virus type I and II infections by antibody reactivity to unique viral epitopes.

A recombinant protein of the human T cell lymphotropic virus type I (HTLV-I) gp46 outer membrane envelope, MTA-4 (residues 129-203), reacted by Western blot with sera from HTLV-I-infected individuals from the United States and Jamaica but not with 24 (10%) of 242 Japanese sera. A related gp46 recombinant protein, MTA-1 (residues 162-209), reacted with all 58 sera from HTLV-I-infected US and Jamaican individuals and 238 of 242 sera from infected Japanese (combined sensitivity of 99%). Neither recombinant showed reactivity to sera from HTLV-II-infected individuals or uninfected controls. The reactivity of recombinant proteins containing the region of HTLV-II gp46 analogous to MTA-1 was also evaluated by Western blot: GH2-K15 (residues 157-205) and GH2-K55 (residues 162-205) reacted with 88 (98%) and 89 (99%), respectively, of 90 sera from HTLV-II-infected individuals but not with sera from HTLV-I-infected individuals or uninfected controls. These recombinant proteins should permit the development of assays to unambiguously confirm and differentiate HTLV-I and HTLV-II infections.

Sudden infant death syndrome in infants of substance-abusing mothers.

A population-based study was performed to determine whether substance abuse during the perinatal period may be a risk factor for sudden infant death syndrome (SIDS). The incidence of SIDS was studied in 2143 infants of substance-abusing mothers (ISAM) born in Los Angeles County during 1986 and 1987 who were reported to the Los Angeles County Department of Health Services because of a history of drug exposure or positive urine test results in the mother, infant, or both. By comparing the ISAM birth reports with records of autopsy-proven SIDS in Los Angeles County, we found 19 SIDS cases in the population of 2143 ISAM, a SIDS rate of 8.87 cases per 1000 ISAM (95% confidence interval 5.3 to 13.8). This was significantly higher than the SIDS rate for the non-ISAM general population: 396 SIDS deaths among 325,372 live births, an incidence rate of 1.22 cases per 1000 births, p less than 0.00001. The age of ISAM at death was 99 +/- 63 (mean +/- SD) days compared with 91 +/- 52 days for the non-ISAM population (not significant). The incidence of SIDS was significantly greater in male infants, during the winter months, in black infants, and in non-Hispanic white infants in the non-ISAM population. Such differences were not observed in the ISAM group. A greater incidence of symptomatic apnea was reported before SIDS for the ISAM than for the non-ISAM population (22% vs 5.4%, p = 0.022). We conclude that ISAM have a higher incidence of SIDS than the non-ISAM general population. However, it was not possible to separate maternal substance abuse from other confounding variables that may also have had an impact on SIDS risk in the ISAM group.