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Biomedical subjects

G G Krueger

Publications and source records attributed to G G Krueger.

At least 19 recordsLinked to original sources
PubMed1999

Regulation of the spatial organization of mesenchymal connective tissue: effects of cell-associated versus released isoforms of platelet-derived growth factor.

Platelet-derived growth factor (PDGF), a mitogen and chemoattractant for mesenchymal cells, occurs as cell-associated or released isoforms. To investigate their in vivo role, human keratinocytes, which normally synthesize both types of PDGF, were genetically modified to overexpress either wild-type PDGF-B (cell-associated) or the truncation mutant PDGF-B211 (released). Cells expressing the mutant isoform released 20 times more PDGF (145 ng/hour/10(7) cells) than cells expressing the wild-type isoform (6 ng/ hour/10(7) cells). When grafted as epithelial sheets onto athymic mice, modified cells formed a stratified epithelium and induced a connective tissue response that differed depending on the PDGF isoform expressed. Expression of PDGF-B211 induced a thick connective tissue with increased numbers of fibroblasts, mononuclear cells, and blood vessels evenly distributed throughout the connective tissue layer, whereas expression of PDGF-B induced a zone of fibroblasts and mononuclear cells localized to the interface of the epidermis and connective tissue, which often disrupted the continuity of the basement membrane. Immunostaining revealed that wild-type PDGF protein was deposited in the basement membrane region. These data suggest that the different binding properties of PDGF isoforms control the spatial organization of cellular events in regenerating mesenchymal tissue in vivo.

Animals↗
PubMed1999

Persistent transgene expression and normal differentiation of immortalized human keratinocytes in vivo.

Cells transduced ex vivo with transgenes encoded on retroviruses have constant and prolonged expression in vitro; however, in vivo expression is quickly lost. Much attention has been directed at methods to circumvent this problem. We have shown that loss of transgene expression does not occur when transduced immortalized 3T3 cells are transplanted to the in vivo setting of athymic mice. Ease of acquisition and potential for clinical application led us to assess the potential of using immortalized human keratinocytes for expression of transgenes in vivo. Human keratinocytes were immortalized with a HPV16-E6/E7 retrovirus, transduced with a lacZ retrovirus, cloned by limiting dilution, seeded onto a physiologic dermal substrate, and transplanted to athymic mice. Six weeks after transplantation, the immortalized transgene expressing keratinocytes had formed an epidermis that was indistinguishable from one formed by nonimmortalized keratinocytes; furthermore, there was no loss of expression of the lacZ gene. These observations show that methods to extend cell survival are an alternative approach to achieving stable and prolonged expression of transgenes in vivo and that HPV16-E6/ E7 immortalized keratinocytes generate an epidermis with normal morphology.

Animals↗
PubMed1998

The safety and efficacy of tazarotene gel, a topical acetylenic retinoid, in the treatment of psoriasis.

OBJECTIVE: To determine the safety and efficacy of topically applied tazarotene gel in the treatment of mild to moderate psoriatic plaques. DESIGN: Two multicenter, double-blind, randomized studies of 6- and 8-week duration, with an 8-week follow-up in the second study. SETTING: Medical center outpatient dermatology services. PARTICIPANTS: One hundred fifty-three adults with 2 bilateral target plaques on the trunk, legs, or arms. INTERVENTIONS: Vehicle gel or 0.01% and 0.05% tazarotene gel administered twice daily to 45 patients (study A), or 0.05% and 0.1% tazarotene gel administered either once or twice daily to 108 patients (study B). MAIN OUTCOME MEASURES: Treatment success and plaque elevation, scaling, and erythema vs time. RESULTS: The 0.01% tazarotene gel showed minimal efficacy. Applications of 0.05% and 0.1% tazarotene gels administered once or twice daily, resulted in significant improvements in plaque elevation, scaling, erythema, and overall clinical severity as early as 1 week. Treatment success rates (defined as > 75% improvement from baseline) were 45% with 0.05% tazarotene gel vs 13% with vehicle gel after 6 weeks of treatment (P < .05; study A) and ranged from 48% to 63% with the various tazarotene treatment regimens after 8 weeks of treatment (study B). These improvements were evident at the 8-week follow-up. Treatment-related adverse effects were generally limited to mild or moderate local irritation and were less frequent with the treatment regimen administered once daily. CONCLUSION: The 0.05% and 0.1% tazarotene gels demonstrated significant efficacy in the treatment of mild to moderate psoriatic plaques that persisted after cessation of treatment.

Administration, Cutaneous↗
PubMed1998

Consensus workshop on the toxic effects of long-term PUVA therapy.

The possibility that there is an increased risk of melanoma in patients with psoriasis treated with psoralen-UV-A (PUVA) therapy has raised concern on the part of physicians and patients about the long-term safety of this treatment. In response to this concern, the National Psoriasis Foundation sponsored a workshop at which invited participants with expertise in PUVA therapy, psoriasis treatment, melanoma and nonmelanoma skin cancer, and epidemiological and clinical trials were asked to develop a consensus on the following 3 issues: the risk of long-term adverse effects of PUVA therapy with emphasis on nonmelanoma and melanoma skin cancer; the guidelines for physicians and patients for selection and use of PUVA therapy with consideration of the risk-benefit ratio of this treatment compared with the risk-benefit ratios of alternative treatments; and the directions for further evaluation of the long-term effects Of PUVA therapy.

Humans↗
PubMed1998

Topical metronidazole maintains remissions of rosacea.

BACKGROUND: Rosacea is a chronic skin disease that requires long-term therapy. Oral antibiotics and topical metronidazole successfully treat rosacea. Because long-term use of systemic antibiotics carries risks for systemic complications and adverse reactions, topical treatments are preferred. OBJECTIVE: To determine if the use of topical metronidazole gel (Metrogel) could prevent relapse of moderate to severe rosacea. DESIGN: A combination of oral tetracycline and topical metronidazole gel was used to treat 113 subjects with rosacea (open portion of the study). Successfully treated subjects (n = 88) entered a randomized, double-blind, placebo-controlled study applying either 0.75% topical metronidazole gel (active agent) or topical metronidazole vehicle gel (placebo) twice daily (blinded portion of the study). SETTING: Subjects were enrolled at 6 separate sites in large cities at sites associated with major medical centers. SUBJECTS: One hundred thirteen subjects with at least 6 inflammatory papules and pustules, moderate to severe facial erythema and telangiectasia entered the open phase of the study. Eighty-eight subjects responded to treatment with systemic tetracycline and topical metronidazole gel as measured by at least a 70% reduction in the number of inflammatory lesions. These subjects were randomized to receive 1 of 2 treatments: either 0.75% metronidazole gel or placebo gel. INTERVENTIONS: Subjects were evaluated monthly for up to 6 months to determine relapse rates. MAIN OUTCOME MEASURES: Inflammatory papules and pustules were counted at each visit. Relapse was determined by the appearance of a clinically significant increase in the number of papules and pustules. Prominence of telangiectases and dryness (roughness and scaling) were also observed. RESULTS: In the open phase, treatment with tetracycline and metronidazole gel eliminated all papules and pustules in 67 subjects (59%). The faces of 104 subjects (92%) displayed fewer papules and pustules after treatment, and 82 subjects (73%) exhibited less erythema. In the randomized double-blind phase, the use of topical metronidazole significantly prolonged the disease-free interval and minimized recurrence compared with subjects treated with the vehicle. Eighteen (42%) of 43 subjects applying the vehicle experienced relapse, compared with 9 (23%) of 39 subjects applying metronidazole gel (P<.05). The metronidazole group had fewer papules and/or pustules after 6 months of treatment (P<.01). Relapse of erythema also occurred less often in subjects treated with metronidazole (74% vs 55%). CONCLUSION: In a majority of subjects studied, continued treatment with metronidazole gel alone maintains remission of moderate to severe rosacea induced by treatment with oral tetracycline and topical metronidazole gel.

Administration, Cutaneous↗
PubMed1998

Comparative efficacy of once-daily flurandrenolide tape versus twice-daily diflorasone diacetate ointment in the treatment of psoriasis.

BACKGROUND: Flurandrenolide tape has recently been listed as a group I topical corticosteroid. There are no studies that compare this product to group I ointments in the treatment of steroid-responsive dermatoses. OBJECTIVE: Our purpose was to determine the relative efficacy of flurandrenolide (4 microg/cm2) tape versus 0.05% diflorasone diacetate ointment in plaque psoriasis. METHODS: Thirty patients participated in an investigator-blinded, randomized, bilateral paired-comparison study of flurandrenolide tape applied to lesions of one side of the body once daily for up to 16 hours versus diflorasone diacetate ointment applied contralaterally twice daily. Lesions were assessed at baseline, then reevaluated at 2 and 4 weeks. RESULTS: Flurandrenolide tape-treated plaques showed consistently greater clearing in terms of erythema, scaling, induration, and treatment success for all plaques, as well as the subset of knee and elbow plaques, when compared with the lesions receiving diflorasone diacetate ointment. CONCLUSION: The efficacy of flurandrenolide tape in the treatment of psoriatic plaques surpasses that of diflorasone diacetate ointment.

Administration, Topical↗
PubMed1998

Efficacy and safety of treatment modalities for psoriasis.

Although there is no cure for psoriasis, a variety of treatments are available to reduce the severity of symptoms and lessen their impact on the patient's quality of life. For patients with less than 20% body surface involvement, topical therapy is the most appropriate choice for initial treatment. Commonly used topical therapies include corticosteroids; calcipotriene, a vitamin D analogue; tazarotene, the first retinoid to be approved for the treatment of psoriasis; and anthralin. Each of these treatments is effective in mild to moderate psoriasis, but each is also associated with varying degrees of safety and tolerability concerns. For patients with more severe, recalcitrant, or extensive psoriasis, phototherapy and systemic therapies are available. These therapies are more effective than topical therapy, but are also associated with significant cutaneous and systemic adverse effects. Phototherapy, alone or in combination with coal tar or psoralen, is very effective in the treatment of moderate to severe psoriasis, but can lead to erythema and pruritus acutely, and long-term problems such as wrinkling, solar elastosis, and an increased risk of skin cancer. Systemic therapies such as acitretin, methotrexate, cyclosporine, hydroxyurea, and thioguanine are also very effective in the treatment of moderate to severe psoriasis, but are all associated with significant systemic toxicity, which requires that patients be monitored carefully. Ultimately, treatment selection for each patient must take into account both the patient's disease severity and expectations for improvement, as well as the risk-benefit ratio associated with each potential therapy.

Administration, Topical↗
PubMed1997

Use of cloned genetically modified human fibroblasts to assess long-term survival in vivo.

Because human fibroblasts are easily brought to tissue culture conditions and can be stably transduced with retroviral vectors encoding transgenes ex vivo, genetically modified fibroblasts are frequently considered in strategies to correct disease with gene therapy. This enthusiasm has been dampened by studies showing that transgene expression by genetically modified fibroblasts diminishes with time in vivo, but not in vitro, for reasons that are unclear. We elected to study this problem using cloned human fibroblasts that had been cloned by limiting dilution and stably transduced with a retroviral vector encoding lacZ ex vivo. These were seeded onto a nonbiodegradable nylon matrix that was transplanted to nude mice. Transgene expression was followed prospectively by histologic exam. Data show that human fibroblasts can withstand the pressure of cloning by limiting dilution. In addition, they can be passaged from 10 to > 20 times, and > 1 x 10(20) of genetically modified fibroblasts can be generated as progeny of one cell. Loss of transgene expression by the cloned genetically modified fibroblasts in vivo occurs in an orderly and progressive fashion, but is not complete by 4 months. Neither the loss nor the persistence of expression appear to be random. These observations are most compatible with the thesis that a major cause of the loss of transgene expression in vivo is secondary to apoptosis of the genetically modified fibroblast. Loss of expression of transgenes in senescent genetically modified fibroblasts occurs more rapidly than in their presenescent counterparts in the age-neutral, in vivo setting of the nude mouse.

Animals↗
PubMed1997

Tazarotene gel, a new retinoid, for topical therapy of psoriasis: vehicle-controlled study of safety, efficacy, and duration of therapeutic effect.

BACKGROUND: Topical therapy providing initial improvement and maintenance of effect after treatment of the large majority of patients with limited, mild to moderate psoriasis is not presently available. Previous topical retinoids have generally been either ineffective or too irritating for therapy of psoriasis. OBJECTIVE: Our purpose was to evaluate a new topical retinoid, tazarotene, in the treatment of stable plaque psoriasis during treatment and posttreatment periods. METHODS: In a double-blind manner, 324 patients were randomly selected to receive tazarotene 0.1% or 0.05% gel, or vehicle control, once daily for 12 weeks and were then followed up for 12 weeks after treatment. RESULTS: Of the total, 318 patients could be evaluated. Tazarotene gels were superior (p < 0.05) to vehicle, often as early as treatment week 1, in all efficacy measures: plaque elevation, scaling, and erythema; treatment response; percentage treatment success (patients with > or = 50% improvement); and time to initial success. Efficacy was equivalent on target lesion sites (trunk or limbs and knees or elbows) and overall. A sustained therapeutic effect was observed for 12 weeks after treatment. Tazarotene gel was cosmetically acceptable. There was low systemic absorption, limiting toxicity to local irritation. CONCLUSION: Once-daily tazarotene was effective and safe as a topical monotherapy for plaque psoriasis, providing rapid reduction of signs and symptoms.

Administration, Topical↗
PubMed1997

Cutaneous gene therapy.

Gene therapy efforts in a variety of tissues have foundered on fundamental technologic barriers, such as difficulties in achieving high-efficiency gene transfer to diseased tissues and in sustaining delivered transgene production. The skin offers an attractive tissue for development of approaches to therapeutic gene delivery by virtue of its accessibility for regulation by topical agents, the ease of gene transfer into cutaneous tissues, and the ready ability to monitor the impact of somatic gene transfer. With the ability of the skin to deliver therapeutic polypeptides to the systemic circulation and the recent molecular characterization of monogenic skin diseases, efforts to target genes to the skin are expected to accelerate. The current status of gene therapy efforts is reviewed, with a special focus on the skin.

Animals↗
PubMed1997

Description of the intrafollicular delivery of large molecular weight molecules to follicles of human scalp skin in vitro.

The objective of this study was to ascertain the elements that govern the intrafollicular delivery of large molecules to follicles of human scalp skin in vitro. The experiments were designed to assess the intrafollicular disposition of drug as a function of size, charge, and formulation. First, fluorescein covalently linked to antisense oligonucleotides and rhodamine-conjugated dextrans were topically applied to fresh human scalp skin in vitro. The drug position in the follicle was qualitatively determined by examining histologic sections of hair-bearing skin taken parallel to the skin surface at various depths and dissected hair follicles via fluorescent microscopy. Using radiolabeled antisense oligonucleotides we demonstrated that these cross sections can also be used to quantitatively localize the intrafollicular delivery of large molecules to follicles of human scalp skin in vitro. Experimental results showed that cationic lipid-based formulations enhanced delivery of oligonucleotides within the follicle. The qualitative analysis also illustrated that cationic lipid-based formulations directed the intrafollicular permeation along the junction of the internal and external root sheath. The charged, lower molecular weight (MW) dextrans permeated into all components of the hair follicle, including the hair shaft. The higher MW dextrans were confined to the follicular structures immediately surrounding the hair shaft. The demonstration of quantitation showed that approximately 0.5% of the applied dose was delivered to the hair bulbs and the deeper skin strata within 24 h of a single application. We conclude that topically applied agents of relatively large MW, in properly formulated delivery vehicles; have the potential to reach pharmacologically active concentrations at the hair bulb. It also should be noted that delivery takes place via the junction of the internal and external root sheath.

Dextrans↗
PubMed1997

Quantitative analysis of l-alpha-acetylmethadol, l-alpha-acetyl-N-normethadol, and l-alpha-acetyl-N,N-dinormethadol in human hair by positive ion chemical ionization mass spectrometry.

A sensitive and specific method was developed for the quantitative analysis of l-alpha-acetylmethadol (LAAM), l-alpha-acetyl-N-normethadol (norLAAM), and l-alpha-acetyl-N,N-dinormethadol (dinorLAAM) in hair. In the development of this method, it was determined that sample pretreatment methods performed by the laboratory greatly affect the measured concentrations of drug and metabolite in hair. Deuterated internal standards were added to 20-mg hair samples and the samples digested overnight in a buffered solution of Protease Type VIII enzyme. Digests were extracted by modification of a liquid-liquid extraction procedure developed previously in our laboratory for the analysis of plasma and tissues. Derivatized extracts were analyzed on a Finnigan MAT 4500 mass spectrometer in positive ion chemical ionization mode using methane and ammonia reagent gases, helium carrier gas, and a DB-5MS (30 m, 0.25-micron film thickness) capillary column. The assay was linear to 50 ng/mg hair (r = 0.99) for all three compounds with a limit of quantitation experimentally determined to be 0.5 ng/mg for LAAM and 0.3 ng/mg for norLAAM and dinorLAAM. Intra-assay precision ranged from 1.0 to 10.5% for the three analytes at concentrations of 0.5, 5.0, and 25.0 ng/mg of hair. Interassay precision ranged from 4.7 to 12.9%. The performance of the method was also evaluated for its utility in detecting and quantitating LAAM, norLAAM, and dinorLAAM in hair from rats (n = 6) that had been administered 3 mg/kg LAAM intraperitoneally once daily for five days. LAAM, norLAAM and dinorLAAM were detectable in pigmented hair at concentrations of 1.27 ng/mg (+/-0.04), 1.28 ng/mg (+/-0.014), and 2.89 ng/mg (+/-0.014), respectively. Five laboratory wash solvents were then evaluated for their effect on the measured concentration of LAAM and metabolites in the rat hair. Phosphate buffer and 1% SDS washes substantially reduced the measured LAAM, norLAAM, and dinorLAAM concentrations by at least 30%, which suggests that drug incorporated into hair is removed (extracted) during the laboratory wash procedures. Wash procedures using methanol, methylene chloride, or water reduced the measured concentrations by no more than 20%. Because measured concentrations of LAAM, norLAAM, and dinorLAAM in hair appear to depend on the specific wash procedures used by a laboratory, quantitative data must be interpreted cautiously based on the sample pretreatment conditions.

Animals↗
PubMed1996

Codeine disposition in human hair after single and multiple doses.

OBJECTIVE: We studied the dose-proportion and time-course relationships for the incorporation of codeine into human hair after the administration of three different groups. SUBJECTS: Male volunteers, with dark hair, were given oral codeine either as a single dose of 60 mg (n = 7) or 120 mg (n = 12) or as multiple doses of 30 mg 3 times daily for 5 days (n = 7) (450 mg total dose). METHODS: Blood and urine were collected for various times for up to 72 h after dosing. Scalp hair was collected initially by plucking (up to 4 weeks) and later by cutting for up to 10 weeks. Plasma, urine, proximal 1 cm of hair and distal hair were each analyzed for codeine and its metabolites by positive-ion chemical ionization ion trap gas chromatography/mass spectrometry. RESULTS: Codeine was detected in the proximal 1 cm of hair within 30 min of an oral 120-mg dose. Codeine was not detected in the distal hair segment until 3 weeks after receiving a dose of codeine. Codeine was detected in distal hair segments for at least 10 weeks at 30 pg mg-1 hair following a single 120 mg codeine dose and at 90 pg mg-1 hair following 30 mg codeine 3 times a day for 5 days. Morphine or the glucuronides of codeine or morphine were not detected in the hair specimens of these subjects. CONCLUSION: Codeine is rapidly distributed into the germanitive elements of hair in a dose-proportional manner. A portion of the codeine remains bound as the hair grows and can be detected in distal hair for up to 10 weeks after a single dose.

Administration, Oral↗
PubMed1996

Evaluation of human skin reconstituted from composite grafts of cultured keratinocytes and human acellular dermis transplanted to athymic mice.

This study evaluates the use of composite grafts of cultured human keratinocytes and de-epidermalized, acellular human dermis to close full-thickness wounds in athymic mice. Grafts were transplanted onto athymic mice and studied up to 8 wk. Graft take was excellent, with no instances of infection or graft loss. By 1 wk, the human keratinocytes had formed a stratified epidermis that was fused with mouse epithelium, and by 8 wk the grafts resembled human skin and could be freely moved over the mouse dorsum. Immunostaining for keratins 10 and 16 and for involucrin revealed an initial pattern of epithelial immaturity, which by 8 wk had normalized to that of mature unwounded epithelium. Mouse fibroblasts began to infiltrate the acellular dermis as early as 1 wk. By 8 wk fibroblasts had completely repopulated the dermis, and blood vessels were evident in the most superficial papillary projections. Dermal elements, such as rete ridges and elastin fibers, which were present in the starting dermis, persisted for the duration of the experiment. Grafts using keratinocytes from dark-skinned donors as opposed to light-skin donors had foci of pigmentation as early as 1 wk that progressed to homogenous pigmentation of the graft by 6 wk. These results indicate that melanocytes that persist in vitro are able to resume normal function in vivo. Our study demonstrates that composite grafts of cultured keratinocytes combined with acellular dermis are a useful approach for the closure of full-thickness wounds.

Animals↗
PubMed1995

Disposition of codeine in female human hair after multiple-dose administration.

Studies of the disposition of codeine into the hair of female subjects (n = 7) were performed after a multiple-dose protocol. Caucasian female subjects with dark-brown-to-black hair were administered a total dose of 450 mg codeine over 5 days (30 mg was administered three times a day for 5 days). Analyses of codeine and metabolites in plasma, urine, and hair were performed by positive ion chemical ionization gas chromatography-mass spectrometry (GC-MS) on a Finnigan Magnum" mass spectrometer. Hair was plucked from the scalp for 5 weeks and subsequently cut from the scalp for up to 10 weeks. Prior to analysis, plucked hair specimens were cut into three segments: (a) a proximal, 1-cm segment, which contained the root, (b) the next distal, 3-cm segment, which was closest to the scalp, and (c) a segment containing all remaining hair to the natural hair tip. in female subjects, the mean (plus or minus standard error of the mean) hair concentration of codeine in the proximal, 1-cm segment from plucked hair was 2.7 ng/mg (+/- 0.55) at 12 h after the last codeine dose; 0.44 ng/mg (+/- 0.20) still remained in this segment at 5 weeks. Codeine was detected in the next 3-cm hair segment (above the scalp) at 1 week; the average codeine concentration for 10 weeks in the 3-cm, distal segment was 0.54 ng/mg (+/- O.05). No codeine was detected in the remaining hair segment (to the tip) at any time. In male subjects studied previously, the mean hair concentration of codeine in the proximal, 1-cm hair segment was 2.6 ng/mg (+/- 0.34) at 12 h after the last codeine dose, and no codeine was detected at 5 weeks. Codeine was not detected in the next 3-cm hair segment (above the scalp) until 3 weeks, and the average mean codeine concentration for 10 weeks was 0.09 ng/mg (+/- 0.01). Differences noted between male and female subjects in distal codeine hair concentrations were not explained by plasma pharmacokinetics.

Administration, Oral↗