Use of subatmospheric pressure to prevent progression of partial-thickness burns in a swine model.

The poorly understood, complex series of events that follows thermal injury frequently results in progressive loss of tissue. The concept of reversing this distinctive series of events has focused on the zone of stasis. Tissues in the zone of stasis that surround burn injuries usually die over a period of 48 to 72 hours postinjury, resulting in a more severe injury. Application of a controlled subatmospheric pressure (125 mm Hg) in an artificially closed space to partial-thickness burns in pigs significantly decreased the maximum depth of cellular death under the burn when the pressure was applied within 12 hours after burn creation (depth of control burns = 0.885 +/- 0.115 mm; subatmospheric pressure treated burns (0-hour delay) = 0.095 +/- 0.025 mm). A decrease in the depth of cell death was noted when subatmospheric pressure was applied for as little as 6 hours. In summary, the application of the negative pressure to partial-thickness burn injuries prevented progression of the wound to a deeper injury in this experimental pig model. A 12-hour working window exists between injury and treatment with reduced pressure, with an application time of as little as 6 hours for successful prevention of injury progression. This technique may represent a new, inexpensive, 'low tech' method for the treatment of partial-thickness burn injuries.

Autologous denatured muscle as a nerve graft.

This study examined the use of freeze-thawed muscle as a nerve graft material in Sprague-Dawley rats. In Group 1 (n = 4), the sciatic nerve was isolated and the incision immediately closed. In Group 2 (n = 4), a 5-mm segment of the nerve was removed and immediately replaced. In Group 3 (n = 50), a 5-mm segment of nerve was removed and muscle (2 x 2 x 5 mm, harvested from the gluteus, frozen in liquid nitrogen, and thawed in sterile water) was sutured in place. The short 5-mm segment of muscle provided an ideal situation for regeneration of myelinated nerve. Sciatic functional indices were comparable in all groups after 8 weeks and at 1 year. Histologic analysis showed comparable nerve regeneration in Groups 2 and 3 at 4 months. Group 3 grafts exhibited new axonal growth distal to the repaired gap at 4 weeks; myelinated fibers were present at 10 weeks. At 1 year, Group 3 nerves had almost the same axon count as contralateral nerves. However, myelin-sheath regeneration in the 5-mm muscle graft was incomplete, at 81 percent of normal, at 1 year.

Arachidonic acid metabolites: effects on inflammation of fetal rabbit excisional wounds.

Uncovered fetal rabbit excisional wounds do not exhibit any classic signs of healing; wounds covered with an impermeable cover do contract, reepithelialize, and exhibit inflammation. Prostaglandin E2 (PGE2) is elevated in amniotic fluid, acting as an immunosuppressant at the maternal-fetal interface. Full-thickness excisional wounds were made on 25-day gestational age rabbit fetuses. Half the wounds were covered with an impermeable cover. Tissue from covered, uncovered, and nonwounded fetuses was examined 72 h after wounding for arachidonic acid metabolites. Uncovered wounds had significantly (P less than or equal to 0.05) elevated levels of PGE2, PGF2 alpha, and 12-HETE versus covered wounds and control tissue. Covered wounds had significantly elevated levels of 15-HETE compared to uncovered and control tissue. The elevated PGE2 in uncovered wounds may act as a fetal immunosuppressant; covered wounds (lower PGE2) developed cellular inflammation. Further investigations of these interactions may permit modulation of adult inflammation.

Analysis of silicon in human breast and capsular tissue surrounding prostheses and expanders.

Diffusion of polydimethylsiloxane from silicone breast prostheses and soft-tissue expanders has been associated with capsular contraction. We used electron dispersive x-ray analysis and scanning electron microscopy to assess the presence of silicon in capsular tissue surrounding three categories of breast prostheses and expanders. Breast and subcutaneous tissues external to the capsules were used as control specimens. Semiquantitative results allowed capsules to be ranked according to implant type. Silicon was localized within the inner 2.0 mm of capsular tissue. The analyses of tissues from 2 patients exhibiting unilateral, Baker grade IV contraction after bilateral placement of prostheses showed less silicon present in the severely contracted capsule than in the less-contracted capsule. Results from this study diminish the importance of silicon as the initiator of capsular contraction.

The female sexual response revisited: understanding the multiorgasmic experience in women.

Although it has been almost 20 years since recorded evidence of multiple orgasms among women emerged, there have been few recent investigations of this phenomenon. The purpose of this study was to understand further the female multiorgasmic experience in relationship to the method of stimulatory activity, namely, masturbation, petting, and sexual intercourse. In addition, single-orgasmic and multiorgasmic women were compared by examination of various sexual and orgasmic behaviors, the role of sex partners, and perceptions of physiological and psychological sexual satisfaction. An anonymous 122-item questionnaire was utilized to obtain the responses of 805 college-educated female nurses, chosen for their perceived ability to verbalize data regarding the anatomical structures and physiological processes associated with sexual responsiveness. The findings indicated that 42.7% of the respondents had experienced multiple orgasms and that several significant differences existed between single-orgasmic and multiorgasmic women.

Monodelphis domesticus: a model for early developmental wound healing.

Fetuses heal significantly differently than adults; amniotic fluid and the fetal environment have profound effects on the fetus' response to excisional wounding. The Brazilian gray short-tailed opossum (Monodelphis domesticus) is presented as a new model for early developmental wound healing. This is a small, docile, pouchless marsupial whose young, at birth, are equivalent to an 8-week gestational age human, which allows investigations of early developmental wound healing exclusive of the amniotic environment. Incisional and excisional wounds were made on the dorsum of pups 1 or 15 days after birth. The pups were killed 1, 3, or 6 days after wounding and were fixed for histology. All incisional wounds were bridged by keratinocytes within 24 hours. Day 1 excisional wounds healed 6 days after wounding with a hypertrophic layer of keratinocytes and no inflammation. Day 15 excisional wounds exhibited inflammation, focal necrosis, and healing by epithelial migration 6 days after wounding. This model allows for investigations into early developmental wound healing and exhibits responses dependent on age similar to prepartum and postpartum young of higher mammals.

In vitro adhesion of endogenous skin microorganisms to breast prostheses.

Bacterial proliferation on polymeric biomaterials varies with the material and microorganism. Subclinical infection is implicated frequently as the initiative factor in capsular contracture around breast prostheses. The ability of endogenous skin microorganisms to produce an exopolysaccharide "slime" is emerging as an important factor in biomaterial colonization. This study was designed to demonstrate the ability of microorganisms of varying slime productivity to colonize, in vitro, different kinds of breast prostheses. Six-millimeter disks from seven kinds of silicone prostheses and polyurethane foam were exposed to three radioactivity labeled strains of bacteria, one slime producer, and two non-slime producers, for 1 hour. Data were expressed as colony-forming units bound per disk. There was no significant difference in adherence between the bacterial strains used, suggesting that initial adherence was nonspecific. The adherence did not appear to be related to surface type, whether smooth or textured, nor to the polymeric composition of the implant material, whether silicone or polyurethane, nor to the presence or absence of slime. Also, adherence was consistent with expected nonspecific bacterial adherence to biomaterials.

Sub-Doppler tunable far-infrared spectroscopy.

The first experimental observations to our knowledge of sub-Doppler linewidths in a cell made using tunable far-infrared radiation are reported. A double-resonance scheme has been used, combining CO(2)-laser infrared radiation with tunable far-infrared radiation to observe a sub-Doppler line shape in an excited vibrational state of CH(3)OH.

Direct frequency measurements of transitions at 520 THz (576 nm) in iodine and 260 THz (1.15 microm) in neon.

The o hyperfine component of the (127)I(2) 17-1 P(62) transition at 520 THz (576 nm) in iodine was measured with respect to the CH(4)-stabilized 88-THz He-Ne laser. A 26-THz CO(2) laser, a color-center laser at 130 THz, and a He-Ne laser at 260 THz were used as transfer oscillators. The measured I(2) frequency was 520 206 808.547 MHz with a total fractional uncertainty of 1.6 x 10(-10). The 1.15-microm (20)Ne Lamb-dip-stabilized laser frequency was 260 103 249.26 MHz with a total fractional uncertainty of 3.1 x 10(-10).

Direct frequency measurement of the I(2)-stabilized He-Ne 473-THz (633-nm) laser.

The absolute frequency of the 473-THz He-Ne laser (633 nm), stabilized on the g or i hyperfine component of the (127)I(2) 11-5 R(127) transition, was measured by comparing its frequency with a known frequency synthesized by summing the radiation from three lasers in a He-Ne plasma. The three lasers were (1) the 88-THz CH(4)-stabilized He-Ne laser (3.39 microm), (2) a 125-THz color-center laser (2.39 microm) with its frequency referenced to the R(II)(26) (13)C(18)O(2)laser, and (3) the 260-THz He-Ne laser (1.15 microm) referenced to an I(2)-stabilized dye laser at 520 THz (576 nm). The measured frequencies are 473 612 340.492 and 473 612 214.789 MHz for the g and i hyperfine components, respectively, with a total uncertainty of 1.6 parts in 10(10). The frequency of the i component adjusted to the operating conditions recommended by the Bureau International des Poids et Mesures is 473 612 214.830 +/- 0.074 MHz.

Frequency measurement of the 260-THz (1.15-microm) He-Ne laser.

Absolute infrared frequency measurement has been extended to 260 THz with the measurement of the strong 1.15-microm laser line in (20)Ne. The frequency was synthesized in nonlinear crystals of CdGeAs(2) and Ag(3)AsS(3) from stabilized CO(2) lasers and the 1.5-microm laser line in (20)Ne. The measured frequency is nu(20)Ne, 1.15 microm = 260.103 284(30) THz.

Extension of absolute-frequency measurements to the visible: frequencies of ten hyperfine components of iodine.

Direct-frequency measurements have been extended into the visible region of the electromagnetic spectrum. The visible frequencies were synthesized by generating the second harmonic of the recently measured 260-THz (20)Ne, 1.15-microm laser with a LiNbO(3) crystal. The absolute frequencies of ten hyperfine components of (127)I(2) near 520 THz are reported.