Reconstructive rhinoplasty

Reconstructive rhinoplasty for larger nasal defects requires a three-dimensional perspective using many of the aesthetic and functional techniques commonly employed in rhinoplasty. There are numerous ways of addressing a deficiency of the internal lining and each technique is detailed. Structural grafting is imperative in order to resist the contracture and collapse of the reconstructive nose. These grafts are also used to enhance contour and definition. Resurfacing of large cutaneous defects is frequently achieved through the midline forehead flap. There are many subtle maneuvers which can significantly impact the final aesthetic outcome and these are discussed below. This article highlights the three-layered approach to subtotal and total reconstructive rhinoplasty.

New approaches in clinical chemistry: on-line analyte concentration and microreaction capillary electrophoresis for the determination of drugs, metabolic intermediates, and biopolymers in biological fluids

The use of capillary electrophoresis (CE) for clinically relevant assays is attractive since it often presents many advantages over contemporary methods. The small-diameter tubing that holds the separation medium has led to the development of multicapillary instruments, and simultaneous sample analysis. Furthermore, CE is compatible with a wide range of detectors, including UV-Vis, fluorescence, laser-induced fluorescence, electrochemistry, mass spectrometry, radiometric, and more recently nuclear magnetic resonance, and laser-induced circular dichroism systems. Selection of an appropriate detector can yield highly specific analyte detection with good mass sensitivity. Another attractive feature of CE is the low consumption of sample and reagents. However, it is paradoxical that this advantage also leads to severe limitation, namely poor concentration sensitivity. Often high analyte concentrations are required in order to have injection of sufficient material for detection. In this regard, a series of devices that are broadly termed 'analyte concentrators' have been developed for analyte preconcentration on-line with the CE capillary. These devices have been used primarily for non-specific analyte preconcentration using packing material of the C18 type. Alternatively, the use of very specific antibody-containing cartridges and enzyme-immobilized microreactors have been demonstrated. In the current report, we review the likely impact of the technology of capillary electrophoresis and the role of the CE analyte concentrator-microreactor on the analysis of biomolecules, present on complex matrices, in a clinical laboratory. Specific examples of the direct analysis of physiologically-derived fluids and microdialysates are presented, and a personal view of the future of CE in the clinical environment is given.

Concentrations of adenosine and its metabolites in the rat retina/choroid during reperfusion after ischemia

PURPOSE

Little is known about the nature of biochemical disturbances during reperfusion after retinal ischemia. Previous studies have suggested that adenosine is responsible for regulation of retinal blood flow soon after ischemia has ended. Therefore, in this study we measured concentrations of adenosine and its metabolites in the rat retina/choroid after brief (10 min) or prolonged (60 min) periods of ischemia, and the functional consequences of inhibiting adenosine metabolism.

METHODS

Ischemia was produced in anesthetized rats by ligation of the central retinal artery. The eyes were frozen in situ and purine nucleoside concentration was determined by high performance liquid chromatography. The functional effects of pre-ischemic inhibition of xanthine dehydrogenase/xanthine oxidase were assessed by measurement of the electroretinogram before, during, and up to 7 days following 60 min ischemia.

RESULTS

Changes in the concentrations of adenosine and its metabolites were significant early in the reperfusion period, and were greater in magnitude and occurred earlier in prolonged, compared to brief, ischemic periods. Concentrations of adenosine, inosine, and hypoxanthine remained elevated for 30 min following the end of 60 min ischemia, and xanthine concentration was significantly elevated until 60 min after the end of either 10 or 60 min of ischemia. The onset of its peak value after ischemia was delayed in comparison to that of adenosine. Ischemia-evoked increases in xanthine concentration were attenuated by inhibition of adenosine deaminase or xanthine oxidase/xanthine dehydrogenase. Pre-ischemic inhibition of xanthine oxidase/xanthine dehydrogenase by oxypurinol (40 or 80 mg/kg intraperitoneally [IP]) resulted in a significant improvement in recovery of the a and b waves of the electroretinogram in comparison to a saline-treated control group.

CONCLUSIONS

These results indicate that adenosine is a major component of the biochemical changes that occur after retinal ischemia. Long-lasting increases in xanthine concentration during reperfusion after ischemia could be a source of oxygen free radicals that may contribute to delayed injury of the retina, attempts to decrease xanthine concentration would ideally be initiated within one hour after the end of ischemia.

Protein purification and cDNA cloning of a cecropin-like peptide from the larvae of fall webworm (Hyphantria cunea)

A proteinous antimicrobial substance was purified from the bacteria-challenged larvae of the fall webworm, Hyphantria cunea. It is a cecropin-like antibacterial peptide which exhibits antibacterial activity against Gram-negative and Gram-positive bacteria, and known as Hyphantria cecropin A. The cDNA clones corresponding to this peptide were isolated from a cDNA library constructed from the bacteria-challenged larvae and obtained complete nucleotide sequences. In addition to the Hyphantria cecropin A sequence, we obtained three other cDNAs exhibiting high sequence similarity with Hyphantria cecropin A. We synthesized the C-terminally amidated peptide of 35 residues based on the deduced sequence of the isolated cDNA of Hyphantria cecropin A. The synthetic peptide exhibited strong antibacterial activity against several microbes including medically important bacteria such as Salmonella, Shigella, and fungus such as Candida. A Southern blot experiment using these cloned cDNAs as probes predicted the existence of multiple forms of Hyphantria cecropin genes.

Pollen tube guidance by the female gametophyte

In flowering plants, pollen grains germinate on the pistil and send pollen tubes down the transmitting tract toward ovules. Previous genetic studies suggested that the ovule is responsible for long-range pollen tube guidance during the last phase of a pollen tube's journey to the female gametes. It was not possible, however, to unambiguously identify the signaling cells within an ovule: the haploid female gametophyte or the diploid sporophytic cells. In an effort to distinguish genetically between these two possibilities, we have used a reciprocal chromosomal translocation to generate flowers wherein approximately half the ovules do not contain a functional female gametophyte but all ovules contain genotypically normal sporophytic cells. In these flowers, pollen tubes are guided to the normal but not to the abnormal female gametophytes. These results strongly suggest that the female gametophyte is responsible for pollen tube guidance, but leave open the possibility that the gametophyte may accomplish this indirectly through its influence on some sporophytic cells.

Primary structure of 6.5k-arginine/glutamate-rich polypeptide from the seeds of sponge gourd (Luffa cylindrica)

The amino acid sequence of 6.5k-arginine/glutamate rich polypeptide (6.5k-AGRP) from the seeds of sponge gourd (Luffa cylindrica) has been determined. The 6.5k-AGRP consists of a 47-residue polypeptide chain containing two disulfide bonds, and a molecular mass calculated to be 5695 Da, which fully coincides with a value of [M+H]+ = m/zeta 5693.39 obtained by matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF MS). The mass spectrometric evidence indicated that 6.5k-AGRP is also present partially truncated at the C-terminus. In our preparations, approximately half of the polypeptide molecules have the C-terminal sequence Arg-Arg-Glu-Val-Asp; the other half lack Val-Asp and end with the glutamic acid, making a total of 45 residues in the polypeptide chain. The two disulfide bonds connect Cys12 to Cys33 and Cys16 to Cys29. Comparison of the amino acid sequence of 6.5k-AGRP with those of the other known proteins included in the PIR protein sequence database showed that it is related to the amino acid sequence of the N-terminal region encoded by the first exon of the cocoa (Theobroma cacao) and cotton seeds vicilin genes, sharing a characteristic two Cys-Xaa-Xaa-Xaa-Cys motif.

In vitro neutralization of hepatitis B virus by monoclonal antibodies against the viral surface antigen

In vitro HBV infection and neutralization were assayed using an anti-preS1 murine monoclonal antibody (1B3) and anti-preS2 (H69K) and anti-S (CS131A) murine-human chimeric antibodies. The 1B3 (IgG1) and H69K (IgG1) was constructed previously and the CS131A was constructed for this study by expressing stably the chimeric heavy and light chains in Chinese hamster ovary cells and purifying from the culture supernatant. Previous study showed that the H69K and CS131A recognize known virus-neutralizing epitopes, while the 1B3 does not. For the assays, adult human hepatocyte primary culture was infected with the adr or ayw subtype of HBV, and the infectivity and subsequent replication was confirmed both by measuring the kinetics of HB-sAg secretion by the infected cells and detecting the intermediate replicative form of HBV DNA in the cells. Next, the hepatocytes were infected with the adr or ayw subtype of the virus that had been preincubated with various concentrations of each of the antibodies and the neutralization of HBV was analyzed. The results showed that the anti-preS2 and anti-S chimeric antibodies exhibited neutralizing activity against both the adr and ayw subtypes of the virus, with approximately 1,000 and 2,000 times higher specific activity than polyclonal hepatitis B immune globulin, respectively, but the anti-preS1 antibody scarcely neutralized the infection. The neutralizing activities of the antibodies were consistent with their epitope specificity and antigenbinding affinity, suggesting that this neutralization assay is specific. The in vitro neutralization assay will be useful for evaluating the neutralizing activity of anti-HBV antibodies before in vivo testing in chimpanzees.

Role of cytochrome P450 enzyme induction in the metabolic activation of benzo[c]phenanthrene in human cell lines and mouse epidermis

The environmental contaminant benzo[c]phenanthrene (B[c]Ph) has weak carcinogenic activity in rodent bioassays; however, the fjord region diol epoxides of B[c]Ph, B[c]Ph-3,4-diol 1,2-epoxides (B[c]PhDE), are potent carcinogens. To determine the role of cytochrome P450 isozymes in the activation of B[c]Ph in MCF-7 cells and the low activation of B[c]Ph in mouse skin, cells of the MCF-7 and the human hepatoma HepG2 cell lines were treated with the potent Ah receptor agonist 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) prior to exposure to B[c]Ph for 24 h. Mice were treated topically with 1 microg of TCDD or vehicle (control) for 73 h and then with 2 micromol of B[c]Ph for 24 h. In MCF-7 cells, TCDD exposure increased B[c]PhDE-DNA adduct levels more than 3-fold with a 10-fold increase in the (-)-B[c]PhDE-2-dA(t) adduct. Treatment of HepG2 cells with TCDD prior to B[c]Ph application did not increase B[c]PhDE-DNA binding. Total B[c]PhDE-DNA adducts increased 3-fold in TCDD-treated mouse epidermis: the majority of the increase resulted from (+)-B[c]PhDE-1-dA adducts. Analysis of P450 enzymes by Western blotting detected a large increase of P4501B1 but almost no increase in P4501A1 in MCF-7 cells exposed to 10 microM B[c]Ph for 24 or 48 h. In HepG2 cells, there were no detectable levels of P4501A1 or P4501B1 after treatment with 10 microM B[c]Ph for 24 h. In contrast, topical application of 2 micromol of B[c]Ph to mouse skin for 48 or 72 h increased P4501A1, but no P4501B1 was detected. As a measure of P450 activity, the metabolism of 7,12-dimethylbenz[a]anthracene (DMBA) was analyzed in microsomes prepared from MCF-7 and HepG2 cells exposed to 0.1% DMSO, 10 microM B[c]Ph, or 10 nM TCDD for 24 or 48 h and from mouse epidermis treated with 1 microg of TCDD, or vehicle control for 72 h, or 2 micromol of B[c]Ph for 48 h. The levels of DMBA metabolites were low or undetectable in microsomes from B[c]Ph-treated MCF-7 and HepG2 cells, but a metabolite pattern consistent with P4501A1 metabolism of DMBA was present in B[c]Ph-exposed mouse epidermal microsomes. TCDD-treated MCF-7 cells, HepG2 cells, and mouse epidermis had DMBA metabolism patterns characteristic of P4501A1 activity. Microsomes from TCDD-treated human cells formed a higher proportion of the proximate carcinogenic metabolite DMBA-3,4-dihydrodiol (16% of total identified metabolites) than TCDD-treated mouse epidermis (2%). In mouse epidermis, the weak ability of B[c]Ph to increase hydrocarbon-metabolizing activity and the increase in mainly P4501A1, leading to formation of the less carcinogenic stereoisomer B[c]PhDE-1, may explain the low carcinogenic activity of B[c]Ph. In a human mammary carcinoma cell line, treatment with B[c]Ph increases mainly P4501B1 and results in formation of a higher proportion of the more carcinogenic B[c]PhDE-2. This indicates that cells in which B[c]Ph treatment increases P4501B1 levels effectively activate B[c]Ph to potent carcinogenic metabolites.

Catalysis of the cysteine conjugation and protein binding of acetaminophen by microsomes from a human lymphoblast line transfected with the cDNAs of various forms of human cytochrome P450

We have previously found that for acetaminophen kinetic differences exist between the hepatic microsomal catalyzed protein binding and cysteine conjugation. We have also observed that the protein binding of acetaminophen is only to intralumenal proteins. Together these data suggested that two pools of the reactive metabolite, N-acetyl-p-benzoquinone imine (NABQI), are formed during the oxidative metabolism of acetaminophen: one on the cytosolic surface and the other within the lumen of the microsomes. This would indicate that some of forms of cytochrome P450 (CYP) catalyzing NABQI formation have their active site on the cytosolic surface and others on the lumenal surface. We have examined this question by comparing the rates of cysteine conjugation and protein binding of acetaminophen by microsomes from lymphoblasts transfected with the cDNAs for human CYPs. We found that CYP2D6 catalyzed only cysteine conjugation; CYP1A2 and 3A4 catalyzed only protein binding; CYP2E1 catalyzed both; and CYP1A1, CYP2A6 and CYP2B6 catalyzed neither. These data suggest that CYP2D6 has its active site only on the cytosolic surface; CYP1A2 and CYP3A4 only on the lumenal surface; and CYP2E1 has catalytic sites on both the lumenal and cytosolic surfaces of the membrane. In mouse studies we have found that ethanol administration increased acetaminophen protein binding by 265% but cysteine conjugation by only 61%. CYP2E1 and CYP2B increased, whereas CYP3A decreased and the others did not change. These data suggest that in control mice CYP2E1 catalyzes the bulk of protein binding, whereas CYP2D catalyzes slightly more cysteine conjugation than does CYP2E1.

Cartilage Viability with Interpolated Skin Flaps: An Experimental Study

Although composite cartilage grafts are often used in conjunction with a midline forehead flap to repair full-thickness nasal defects, the timing of pedicle division, which optimizes cartilage viability, has yet to be determined. A rabbit animal model was designed to investigate this question. The skin flap pedicle was divided at 0 days, 4 days, 3 weeks, 6 weeks, and 10 weeks in each of five groups of five animals. Although early pedicle division led to partial skin flap necrosis, the cartilage grafts tolerated this ischemic period better. Cartilage viability was approximately 70% and did not differ significantly between the five groups. It is concluded that a larger composite graft and better definition of the skin flap's critical period are needed to determine optimum timing for pedicle division in this animal model.

Cartilage viability with interpolated skin flaps: an experimental study

Although composite cartilage grafts are often used in conjunction with a midline forehead flap to repair full-thickness nasal defects, the timing of pedicle division, which optimizes cartilage viability, has yet to be determined. A rabbit animal model was designed to investigate this question. The skin flap pedicle was divided at 0 days, 4 days, 3 weeks, 6 weeks, and 10 weeks in each of five groups of five animals. Although early pedicle division led to partial skin flap necrosis, the cartilage grafts tolerated this ischemic period better. Cartilage viability was approximately 70% and did not differ significantly between the five groups. It is concluded that a larger composite graft and better definition of the skin flap's critical period are needed to determine optimum timing for pedicle division in this animal model.

Primary structure and allergenic activity of trypsin inhibitors from the seeds of buckwheat (Fagopyrum esculentum Moench)

The complete amino acid sequences of two trypsin inhibitors BWI-2a and BWI-2b from the seeds of buckwheat (Fagopyrum esculentum Moench) were determined. BWI-2b consists of 51 amino acid residues containing two disulfide bonds. BWI-2a shares all amino acids with BWI-2b except for the C-terminal tripeptide: BWI-2a lacks Glu-Gly-Asn and ends with the Asp residue, making a total of 48 residues in the chain. The two disulfide bonds connect Cys11 to Cys32 and Cys15 to Cys28. BWI-2b shows no relatedness to the other buckwheat trypsin inhibitor reported [Belozersky et al. (1995) FEBS Lett. 371, 264-266]. Sequence comparison of BWI-2b with those of the other proteins included in PIR showed that BWI-2b is significantly homologous to the N-terminal region of storage proteins classified in the vicilin family. Furthermore, the allergenic activity of BWI-2b and the other buckwheat trypsin inhibitor BWI-1 was examined using the radioallergosorbent test. The result indicated that both inhibitors BWI-2b and BWI-1 have IgE binding activity, albeit to a low extent, suggesting that they might be minor allergenic proteins in buckwheat seeds.

Magnetic resonance imaging in hemospermia

PURPOSE

We evaluated the prostate and seminal tract with magnetic resonance imaging (MRI) in patients with hemospermia.

MATERIALS AND METHODS

To evaluate the prostate and seminal tract in 17 patients 20 to 59 years old (mean age 44) with hemospermia we performed transrectal ultrasound and MRI using an endorectal surface coil with a 1.5 tesla unit. Mean duration of hemospermia was 32 months (1 week to 16 years).

RESULTS

Abnormalities were noted on transrectal ultrasound in 15 of the 17 patients (88%) and on MRI in all. Of the 12 cases of hemorrhage 10 involved the seminal vesicle and 2 involved the ejaculatory duct. There were 12 cystic lesions, including 7 in the müllerian and 5 in the ejaculatory ducts. Of 19 cases calculi were detected in the prostate in 5, seminal vesicle in 8, and ejaculatory and müllerian duct cysts in 4 and 2, respectively. There was 1 case of prostatic atrophy and 1 wolffian duct anomaly associated with an ejaculatory duct cyst, ectopic ureterocele and absence of the left kidney.

CONCLUSIONS

MRI with an endorectal surface coil is a powerful modality for evaluating the seminal tracts of patients with hemospermia. It can be performed clinically when transrectal ultrasonography is not satisfactory.

Protein purification and nucleotide sequence of a lysozyme from the bacteria-induced larvae of the fall webworm, Hyphantria cunea

A protein with lytic activity against Micrococcus luteus was purified from the hemolymph of the fall webworm, Hyphantria cunea, larvae challenged with live E. coli. A bacteriolytic protein of about 14,000 daltons in mass was purified by cation exchange chromatography and reverse-phased HPLC. The optimum pH and optimum temperature range for activity were around pH 6.2 and 50 degrees C, respectively, in a 100 mM phosphate buffer. The amino-terminal amino acid sequence of this protein was determined and the corresponding cDNA was isolated and analyzed. The deduced protein of 142 amino acid residues was composed of a putative leader sequence of 20 residues and the mature enzyme of 122 residues. The cloned lysozyme gene was strongly induced in response to bacterial injection, implying that the enzyme is a part of the immune response of H. cunea. Comparison with other known lysozyme sequences shows that our lysozyme belongs to the chicken lysozyme.

Generation and characterization of a humanized antibody with specificity for preS2 surface antigen of hepatitis B virus

For the prevention of hepatitis B virus (HBV) infection, monoclonal antibodies (mAbs) against the surface antigens of HBV would offer several advantages over the current human polyclonal antibody. We have developed a humanized antibody with specificity for the preS2 surface antigen of HBV and evaluated the neutralizing activity of the humanized antibody. The complementarity-determining regions of the heavy and light chains of a murine monoclonal antibody (H8) were grafted onto the variable regions of a highly homologous human anti-Sm antibody, which were then combined with the constant regions of human gamma 1 and kappa, respectively. The affinity of the resulting humanized antibody (Z6B) was about one tenth that of the chimeric antibody. The new version (ZP39) of the humanized antibody, which was constructed by substituting the heavy-chain framework residue at position 94 of the Z6B with original mouse residue, showed almost the same affinity as that of the chimeric antibody. The evaluation of the HBV neutralizing activity of ZP39 using in vitro infection of adult human hepatocyte primary culture by HBV showed that it had a specific activity that was approximately 1000 times higher than commercially available polyclonal hepatitis B immune globulin. We expect that the present humanized antibody will be useful in the prevention of HBV infection.

The liposhaver in facial plastic surgery. A multi-institutional experience

OBJECTIVE

To report a multi-institutional clinical experience with the liposhaver in facial plastic surgery.

DESIGN

Nonrandomized, nonblinded, multi-institutional evaluation of the liposhaver in a clinical setting in patients presenting for cosmetic facial liposuction.

INTERVENTIONS

Cosmetic facial surgery with the liposhaver was performed in 19 patients (21 procedures) who underwent submental lipectomy, facelift with defatting beneath the facelift flap, and/or correction of deep nasolabial folds. Standardized preoperative and postoperative photographs were obtained. Fat obtained from the abdomen of 1 patient was also studied histologically. This fat was excised sharply and was then liposhaved at varying oscillation speeds.

OUTCOME MEASURES

Subjective evaluation by the operating surgeons.

RESULTS

The liposhaver was used successfully in all cases. The fat was cleanly shaved and the contour results were even, without dimpling or asymmetry. Operative time was comparable to that for conventional liposuction. Preferred cannula sizes and settings were determined. There were no cases of facial nerve injury, no evidence of increased bleeding intraoperatively, and no hematomas in the immediate postoperative period. One patient developed a small hematoma on postoperative day 5 that was effectively treated with needle aspiration and a pressure dressing. Histologic evaluation of liposhaved abdominal fat showed normal fat cells and well-preserved architecture.

CONCLUSIONS

The liposhaver offers a precise alterative to conventional liposuction. It may be less traumatic because it requires low suction pressures and does not rely on the potentially bruising, vigorous, back-and-forth motion for fat extraction typical of conventional liposuction.

Measurement of purine nucleoside concentration in the intact rat retina

Adenosine, produced from the decomposition of adenosine triphosphate, is believed to provide protective effects during ischemia. On the other hand, adenosine metabolites may serve as precursors for oxygen free radical formation. These substances have not been previously measured in intact vertebrate retina, where adenosine and its metabolites may play a role in the pathogenesis of ischemic injury. The small tissue mass of the retina, particularly in rats, renders these measurements challenging. Furthermore, accurate measurement of purine nucleosides requires immediate cessation of ongoing adenosine metabolism. Concentrations of adenosine and its purine nucleoside metabolites inosine, hypoxanthine, and xanthine in the retina of ketamine/xylazine-anesthetized rats were measured after in situ freezing using high-performance liquid chromatography. The retina was removed from the frozen eyes and analyzed. Quantitative measurements were made possible through the use of an internal standard. Ischemia was induced by ligation of the central retinal artery. Retinal purine nucleoside concentrations did not differ between the two eyes of the rat under control conditions, and there was no effect of placement of the ligating suture itself compared to completely unmanipulated eyes. Use of two different in situ freezing methods yielded comparable results. To evaluate the impact of a period of ischemia, one retina of each rat was ischemic for 30 min, and the other, non-ischemic. Our measurements were associated with a high degree of reproducibility and minimal variability, and significant changes in purine nucleoside concentrations were detectable in the retina after 30 min of ischemia. Our method may be used to assess the role of adenosine and its metabolites in the pathogenesis of ischemic neuronal injury, including in the retina.

Metabolism of phenytoin by the gingiva of normal humans: the possible role of reactive metabolites of phenytoin in the initiation of gingival hyperplasia

Gingival hyperplasia is a well-known complication of therapy with cyclosporine, calcium channel blockers, and phenytoin. It is characterized by the presence of inflammation and a marked fibrotic response. The mechanism of this adverse reaction is unknown. We propose that it may be initiated by the metabolic activation of these drugs to form reactive metabolites. These then cause cellular injury and lead to the gingival hyperplasia. To evaluate this hypothesis we examined phenytoin metabolism and the cytochrome P450 contents of gingival tissues from 10 patients undergoing surgery for various periodontal conditions. We found that microsomes obtained from the gingiva show significant phenytoin hydroxylase activity as determined by the production of 5-(4'-hydroxyphenyl)-5-phenylhydantoin (HPPH) (range, 12.8 pmol HPPH/min.mg microsomal protein to 276.9 pmol HPPH/min.mg microsomal protein; rat control, 133.7 +/- 11.5 pmol HPPH/min.mg microsomal protein). We also found that CYP1A1, CYP1A2, CYP2C9, CYP2E1, and CYP3A4 were present in these microsomes. We detected no CYP2B6 or CYP2D6. We believe that these data support our hypothesis that the proliferative inflammation observed with drugs such as phenytoin, nifedipine, and cyclosporine may be initiated by the formation of reactive metabolites and that the formation of these metabolites may be catalyzed by one or more CYPs found in the gingiva. These metabolites may then cause cellular injury and induce a reactive inflammatory response, followed by fibroblastic proliferation. This proliferation leads to the excess collagen deposition observed with gingival hyperplasia.

Role of ischemic gradient in neovascularization of interpolated skin flaps

OBJECTIVES

To investigate the significance of the ischemic gradient between interpolated skin flaps and the recipient bed and to determine its role in flap viability.

DESIGN

Bilateral interpolated skin flaps were elevated in 10 pigs and intravenous fluorescein was used to define a border of pedicle perfusion. Flaps were assigned to 1 of 2 groups: proximal flaps, which were contained within the fluorescein border, or distal flaps, which extended 3 cm beyond the fluorescein border. Flaps were then transferred to an adjacent cutaneous defect and pedicles were divided after 2 weeks. The flap and pedicle portions were evaluated separately and viability was quantified.

SUBJECTS

Ten adolescent pigs with bilateral flaps. None were withdrawn.

INTERVENTION

Intravenous fluorescein (20 mg/kg) to determine extent of perfusion in the flaps.

RESULTS

Proximal flaps (n = 10) maintained excellent viability with the pedicles attached. After pedicle division, however, partial flap and pedicle necrosis developed. Distal flaps (n = 10) promptly showed signs of ischemia and congestion but soon showed improved vascularity. A statistically significant improvement was seen in mean percent viability of the distal group compared with the proximal group (P < .05) (Student t test).

CONCLUSION

The more ischemic flap-pedicle complex resulted in greater viability after pedicle division. The ischemic gradient seemed to represent a potent angiogenic stimulus to the recipient bed.

Effect of transforming growth factor-beta on plasminogen activator production of cultured human uveal melanoma cells

PURPOSE

Human uveal melanoma cells have been shown to produce plasminogen activator (PA), an enzyme which can enhance tumor metastasis by promoting degradation of extracellular matrix. This study used cultured human uveal melanoma cells to determine whether the PA production of uveal melanoma cells could be modulated by transforming growth factor-beta2 (TGF-beta2), a mitogen present in the uvea.

METHODS

Five different cell lines of human uveal melanoma of differing cellular morphology (2 spindle, 2 epithelioid, 1 mixed) derived from tumors from different locations in the eye (3 choroidal, 1 ciliochoroidal, 1 orbital) were grown in serum-free media, in the presence or absence of TGF-beta2 (1ng/ml to 100ng/ml). After 24 hrs, the conditioned media were collected and quantitated for PA activity by measuring the radial diffusion in fibrin-agarose clot and for total PA concentration using an enzyme-linked immunoassay.

RESULTS

Among the cell lines studied, all produced PA. Cell lines derived from intraocular tumors secreted tissue-type PA (tPA), and TGF-beta2 stimulated tPA activity and secretion of cell lines containing epithelioid cells but had no effect on spindle cells. In contrast, tumor cells isolated from an orbital tumor secreted urokinase (uPA), activity and secretion of which was inhibited by TGF-beta2.

CONCLUSIONS

We conclude that cultured human uveal melanoma cells produce either tPA or uPA, and TGF-beta2 can have a variable effect on PA production of these cells.