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Biomedical subjects

R R Anderson

Publications and source records attributed to R R Anderson.

258 records · Page 15Linked to original sources
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Reduction of regrowing hair shaft size and pigmentation after ruby and diode laser treatment.

Laser pulses which selectively damage pigmented hair follicles are a useful treatment for hypertrichosis. Clinically, regrowing hairs are often thinner and lighter after treatment. In this study, hair shaft diameter and optical transmission (700 nm) were measured before and after ruby (694 nm) and diode (800 nm) laser irradiation. Hair was collected from 47 and 41 subjects treated with ruby (0.3 ms and 3 ms) and diode (10-20 ms) lasers, respectively. "Responders" were defined as subjects with significant long-term hair loss as determined by hair counts at 9 and/or 12 months after treatment. In ruby laser responders (34/47), regrowing hairs were significantly both thinner (decreased diameter) and lighter (increased transmission). In "nonresponders" (13/47), regrowing hairs were lighter, but not thinner. The regrowing hair shaft absorption coefficient (as calculated assuming Beer's law) was significantly decreased by 0.3 ms ruby laser treatment, but was not changed by 3 ms ruby laser or diode laser treatment. After diode laser treatment, 38 of the 41 subjects were responders and regrowing hairs were both thinner and lighter. These results show that laser treatments can affect structural recovery (size of hair), follicular pigmentation (hair absorption coefficient), or both. Regrowth of thinner hair (decreased shaft diameter) occurs in conjunction with actual loss of hair. After long pulses (3 ms ruby; diode), regrowing hair was thinner and also lighter to an extent related to the decrease in hair diameter. In contrast, short ruby laser pulses (0.3 ms) appeared to be capable of inhibiting follicular pigmentation per se, in addition to affecting the hair diameter. This may account for the complete regrowth of lighter hair in "nonresponders" treated with 0.3 ms pulses. Laser-induced reduction in hair diameter and/or pigmentation are both long-term responses which confer cosmetic benefits in addition to actual hair loss.

Adult↗
PubMedDate not supplied

The thermal properties of bovine joint capsule. The basic science of laser- and radiofrequency-induced capsular shrinkage.

Orthopaedic surgeons have recently adapted the holmium: yttrium-aluminum-garnet (YAG) laser for the shrinkage of capsular tissues for treatment of glenohumeral instability. The molecular mechanism of capsular shrinkage has not been documented to date. This study examined the effects of heating on bovine calf knee capsule and subsequent shrinkage of the capsule. Capsule specimens were placed in a saline bath at temperatures ranging from 55 degrees to 75 degrees C for 1, 3, 5, and 10 minutes. Shrinkage was quantified by digital imaging, and the tissue was examined by light and polarized light microscopy. Tissue contraction was not measurable at or below 57.5 degrees C. At 60 degrees C, tissue shrinkage occurred with corresponding basophilic staining and loss of birefringence in collagen fibers. For specimens heated at 60 degrees C and 62 degrees C, shrinkage directly correlated with duration of thermal exposure. Maximal shrinkage of approximately 50% in length occurred at and above 65 degrees C with thermal exposures of 1 minute or greater. This study demonstrates that thermal shrinkage of bovine knee capsule correlates with denaturation of collagen fibers and depends on both time and temperature. Capsular shrinkage treatments may be performed with any energy source that is capable of well-controlled heating of capsular tissue and does not depend on the special properties of laser light.

Animals↗