Induction of TCR-gamma delta expression on triple-negative (CD3-4-8-) human thymocytes. Comparative analysis of the effects of IL-4 and IL-7

It is well established that IL-4 and IL-7 control the differentiation of TCR-gamma delta-expressing cells from CD3/TCR-negative thymic precursors. In this study, we have compared the in situ expression of IL-4 and IL-7 mRNA in human postnatal thymus with the in vitro effect of IL-4 and IL-7 on the expansion of TCR-gamma delta + cells from highly purified CD3-4-8- triple-negative thymocytes. IL-4 mRNA expression was restricted to subcapsular regions of the human thymus, whereas cells expressing IL-7 mRNA were distributed throughout the thymic tissue, with some enrichment in subcapsular and cortical regions. Epithelial cells of the outer layer of Hassall's corpuscle strongly expressed IL-7 mRNA. IL-7 but not IL-4 or IL-2, stimulated strong proliferative activity and cellular expansion of triple-negative thymocytes. All three induced the appearance of TCR-gamma delta + cells within 4 days of culture. In the presence of IL-4 or IL-2, 30 to 55% of viable cells were TCR-gamma delta + after 5 to 9 days, whereas only 10 to 15% triple-negative thymocytes cultured with IL-7 expressed TCR-gamma delta. However, comparable absolute numbers of viable TCR-gamma delta + thymocytes were recovered when triple-negative thymocytes were cultured with IL-4 or IL-7, but not with IL-2. Taken together, our results suggest that IL-4 and IL-7 (both of which are produced in situ in thymic tissue) play equally important roles in the in vitro generation of TCR-gamma delta + thymocytes from triple-negative precursor cells.

[Investigation of the relationship between white lesion of vulva and human epidermal growth factor]

The levels of human epidermal growth factor (hEGF) were determined by radioimmunoassay (RIA) in dermal specimens taken from lesion skin and normal vulva skin in 30 patients with white lesions of the vulva as well as their urine specimens, and in another 29 vulva biopsy and 37 urine samples from healthy women without the disease as the control group. The results showed that the mean hEGF levels in lesion vulva skin, normal vulva skin of the patients and normal vulva skin of healthy women were 163.40 +/- 97.89 micrograms/L, 119.00 +/- 53.13 micrograms/L and 67.84 +/- 14.72 micrograms/L respectively. The level of hEGF in lesion skin was higher than that in the normal vulva skin of same patients (P < 0.05) and also higher than that in the normal skin of healthy women (P < 0.01). The hEGF level in normal skin of the patients was higher than that in healthy women (P < 0.01). The hEGF level in lesion skin had no relationship with pathological types. The hEGF levels in urine had no significant difference between the patients and healthy women. The results suggested that high levels of hEGF in local vulva lesions may play an important role in the pathogenesis of white lesions of the vulva.

A randomized trial of three antipneumocystis agents in patients with advanced human immunodeficiency virus infection. NIAID AIDS Clinical Trials Group

BACKGROUND

We evaluated the effectiveness of three treatment strategies for the prevention of a first episode of Pneumocystis carinii pneumonia in patients infected with the human immunodeficiency virus (HIV).

METHODS

In an open-label trial, 843 patients with HIV infection and fewer than 200 CD4+ cells per cubic millimeter received zidovudine plus one of three randomly assigned prophylactic agents, beginning with trimethoprim-sulfamethoxazole, dapsone, or aerosolized pentamidine and followed by a defined sequence of other drugs to be used in cases of intolerance.

RESULTS

The estimated 36-month cumulative risks of P. carinii pneumonia were 18 percent, 17 percent, and 21 percent in the trimethoprim-sulfamethoxazole, dapsone, and aerosolized-pentamidine groups, respectively (P = 0.22). The difference in risk among treatment strategies was negligible in patients entering the study with 100 or more CD4+ lymphocytes per cubic millimeter. In those entering with fewer than 100 CD4+ cells per cubic millimeter, the risk was 33 percent with aerosolized pentamidine, as compared with 19 percent with trimethoprim-sulfamethoxazole and 22 percent with dapsone (P = 0.04). The lowest failure rates occurred in patients receiving trimethoprim-sulfamethoxazole, and failures were more common with 50 mg of dapsone than with 100 mg. Toxoplasmosis developed in less than 3 percent of patients. Of the patients assigned to the two systemic therapies, only 23 percent were receiving their assigned drug and dose when they completed the study. The median survival was approximately 39 months in all three groups, and the mortality attributable to P. carinii pneumonia was only 1 percent.

CONCLUSIONS

In patients with advanced HIV infection, the three treatment strategies we examined have similar effectiveness in preventing P. carinii pneumonia. Strategies that start with trimethoprim-sulfamethoxazole or with high-dose dapsone, rather than aerosolized pentamidine, are superior in patients with fewer than 100 CD4+ lymphocytes per cubic millimeter.

A randomized trial comparing fluconazole with clotrimazole troches for the prevention of fungal infections in patients with advanced human immunodeficiency virus infection. NIAID AIDS Clinical Trials Group

BACKGROUND

Cryptococcal meningitis and other serious fungal infections are common complications in patients infected with the human immunodeficiency virus (HIV). Fluconazole is effective for long-term suppression of many fungal infections, but its effectiveness as primary prophylaxis had not been adequately evaluated.

METHODS

We conducted a prospective, randomized trial that compared fluconazole (200 mg per day) with clotrimazole troches (10 mg taken five times daily) in patients who were also participating in a randomized trial of primary prophylaxis for Pneumocystis carinii pneumonia.

RESULTS

After a median follow-up of 35 months, invasive fungal infections had developed in 4.1 percent of the patients in the fluconazole group (9 of 217) and in 10.9 percent of those in the clotrimazole group (23 of 211; relative hazard, as adjusted for the CD4+ count, 3.3; 95 percent confidence interval, 1.5 to 7.6). Of the 32 invasive fungal infections, 17 were cryptococcosis (2 in the fluconazole group and 15 in the clotrimazole group; adjusted relative hazard, 8.5; 95 percent confidence interval, 1.9 to 37.6). The benefit of fluconazole was greater for the patients with 50 or fewer CD4+ cells per cubic millimeter than for the patients with higher counts. Fluconazole was also effective in preventing esophageal candidiasis (adjusted relative hazard, 5.8; 95 percent confidence interval, 1.7 to 20.0; P = 0.004) and confirmed and presumed oropharyngeal candidiasis (5.7 and 38.1 cases per 100 years of follow-up in the fluconazole and clotrimazole groups, respectively; P < 0.001). Survival was similar in the two groups.

CONCLUSIONS

Fluconazole taken prophylactically reduces the frequency of cryptococcosis, esophageal candidiasis, and superficial fungal infections in HIV-infected patients, especially those with 50 or fewer CD4+ lymphocytes per cubic millimeter, but the drug does not reduce overall mortality.

[A research on serum, urine and tumor tissue hyaluronate assays for detecting malignant ovarian tumors]

Hyaluronate contents were determined by radioimmunoassay in 91 samples of serum, 88 samples of urine and 32 samples of ovarian tumor tissue from patients with benign and malignant tumors and from healthy subjects. The mean serum hyaluronate level in patients with malignant ovarian tumors (mean, 155.99 micrograms/L, range, 20 to 680 micrograms/L) was significantly higher than that in patients with benign ovarian tumors (mean, 84.2 micrograms/L; range, 20 to 188 micrograms/L) and that in healthy subjects (mean, 57 micrograms/L; range, 2 to 110 micrograms/L). The mean urine hyaluronate level in the malignant group (mean, 307.83 micrograms/L; range 50 to 750 micrograms/L) also was significantly higher than that in the normal control group (mean, 146 micrograms/L; range, 40 to 242 micrograms/L). The results suggest that serum and urine hyaluronate determination in the detection of malignant ovarian tumors is of clinical value.

Differential effects of interleukin-2 and interleukin-7 on the induction of CD4 and CD8 expression by double-negative human thymocytes

Expression of cell surface CD4 (in the absence of CD3/T cell receptor) characterizes an early stage of intrathymic T cell development. Here, we investigated the appearance of CD4 and CD8 expression on highly purified CD4-8- double-negative human thymocytes in response to interleukin (IL)-7 and IL-2. While IL-7 preferentially promoted the appearance of CD4 single-positive and CD4+8+ double-positive thymocytes, IL-2 primarily induced CD8 single-positive thymocytes. A significant fraction of CD4 single-positive cells generated from double-negative thymocytes via IL-7 lacked cell surface CD3 expression. In contrast, the majority of CD8 single-positive cells generated from double-negative thymocytes via IL-2 coexpressed CD3. We conclude that IL-7 and IL-2 exert differential effects on the differentiation of early human T cell progenitors.

Amino acid sequence of rat kidney glutathione synthetase

Glutathione (GSH) synthetase [gamma-L-glutamyl-L-cysteine:glycine ligase (ADP-forming), EC 6.3.2.3], an enzyme present in almost all cells, catalyzes the ATP-dependent synthesis of GSH from gamma-L-glutamyl-L-cysteine and glycine. Highly purified preparations of the enzyme have been obtained from rat kidney and several lower forms. The rat kidney enzyme (M(r), 118,000), which contains approximately 2% carbohydrate, is composed of two apparently identical subunits. The cDNA encoding rat kidney GSH synthetase was isolated from a rat kidney lambda gt11 cDNA library by immunoscreening with an antibody prepared against the isolated enzyme. The cDNA contains 1905 nucleotides and an open reading frame of 1422 nucleotides coding for 474 amino acids. The cDNA has a 3' untranslated region of 439 nucleotides, which includes a poly(A) tail. The deduced amino acid sequence (M(r), 52,344) contains all five of the peptide sequences that were independently determined by Edman degradation. The cDNA was expressed in Escherichia coli. The amino acid sequence of the rat kidney enzyme has no significant similarity to that of the enzyme from E. coli and shows some similarity to those deduced for the yeast and frog enzymes. Knowledge of this amino acid sequence is expected to facilitate elucidation of the sequence of the corresponding human enzyme and to lead to studies on the biochemical mechanisms involved in human GSH synthetase deficiency as well as to development of improved methods for prenatal diagnosis of these inborn diseases.

Elevated plasma chitotriosidase activity in various lysosomal storage disorders

Recently a striking elevation of the activity of chitotriosidase, an endo beta-glucosaminidase distinct from lysozyme, was found in plasma from patients with Gaucher type I disease (McKusick 230800). Plasma chitotriosidase originates from activated macrophages and this elevation is secondary to the basic defect in Gaucher disease. To investigate the specificity of this phenomenon, we have investigated 24 different lysosomal storage diseases. In 11 different diseases increased chitotriosidase activity in plasma was found (in 28% of the patients). None of these diseases showed elevations as high as in Gaucher disease. Chitotriosidase was not significantly elevated in plasma from 20 different non-lysosomal enzymopathies or in plasma from patients with infectious diseases associated with hepatomegaly. The results show that marked elevation of chitotriosidase activity in plasma appears to be specific for Gaucher disease. The data further suggest that elevated levels of chitotriosidase activity in plasma from patients with unexplained diseases may be indicative for a lysosomal disorder.

Cytokines involved in intrathymic T cell development

Cytokines play an important role in intrathymic T cell development. Over the past several years, genes of newly discovered cytokines have been cloned, and the respective recombinant proteins have become available for functional studies of T cell development. In this paper we have attempted to review the respective roles of interleukins 1, 2, 4, 6, and 7. Special emphasis was given to interleukin 7 which has been shown to play a key role in early T cell differentiation.

Serum hyaluronate in the assessment of liver endothelial cell function after orthotopic liver transplantation in the rat

This study was designed to evaluate the use of serum hyaluronate as a marker of liver endothelial cell function after liver transplantation. We performed orthotopic liver transplantation in both isogeneic and allogeneic rejector models. After transplantation, hepatocyte function was assessed on the basis of serum ALT and total bilirubin levels, and liver endothelial cell function was judged on the basis of serum hyaluronate levels. Significant increase of hyaluronate in the rejector model, compared with the isogeneic model, was seen before any significant results could be obtained from conventional liver function tests. The impaired metabolism of hyaluronate in the rejector model was observed after intravenous injection of trace amounts of radioactive material. Serial studies demonstrate that the endothelial cell is a more susceptible target for the immune response than the hepatocyte. Serum hyaluronate concentration may be a better indicator in the early assessment of graft function. We also examined serum hyaluronate levels to evaluate cold ischemia-reperfusion injury to the liver endothelial cells in the isogeneic model. At 2 hr after reperfusion, hyaluronate levels in the 6-hr cold ischemia (nonviable allograft) group were significantly higher than in the 1-hr and 3-hr cold ischemia (viable allograft) groups. However, there was little difference between the viable allograft groups. After an intravenous injection of 1 mg/kg hyaluronate, the hyaluronate elimination rate in the 3-hr group was distinctly slower than that in the 1-hr group. These data indicate that the hyaluronate elimination rate may be a more sensitive marker of liver endothelial cell function in viable liver after a short period of ischemia.

Accelerated G1-transit following transient inhibition of DNA replication is dependent on two processes

Accelerated G1 transit in HeLa cells develops after a temporary inhibition of DNA synthesis in the previous generation. G1 acceleration has been found to be dependent on (1) the cell-cycle position at the time of the inhibition and (2) the duration of the inhibition. The degree of G1 acceleration correlates with the position in S-phase at which DNA synthesis is blocked. G1 transit time decreases gradually beginning with early S blocks and reaches a minimum when DNA synthesis is inhibited at mid S-phase. A minimum of 4 h continuous inhibition at this position resulted in maximum G1 acceleration. Unbalanced growth, i.e., the nonspecific increase in total protein or RNA levels that results from inhibition of DNA synthesis, did not correlate with the decrease in G1 transit time. On the other hand, one-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis showed specific changes in four nuclear proteins of molecular weights 120, 66, 57, and 51 kDa in cells immediately following release from inhibition of DNA synthesis at mid S-phase. A Western blot analysis of cyclins D and E showed an increased accumulation of cyclin E at 0, 1, 5, 7, and 12 h following cell release from the mid S-phase block. Therefore, it is unlikely that changes in the ratio of protein/DNA or RNA/DNA are responsible for the decrease in G1 transit times as suggested by the unbalanced growth model of G1 acceleration. Instead, G1 acceleration may result from the accumulation during S-phase blockage, and subsequent retention through G2 and mitosis, of specific proteins required for cell transit through G1 in the next cell cycle.

Assessment of proliferating cell nuclear antigen (PCNA) in breast cancer using anti-PCNA PC10 and 19A2: correlation with 5-bromo-2'-deoxyuridine or tritiated thymidine labeling and flow cytometric analysis

We compared immunohistochemical staining by two monoclonal antibodies, PC10 and 19A2, to standard methods for cell proliferation, 3H-TdR or BrdU labeling index (S-LI) and S-phase fraction by flow cytometry (S-flow). One hundred thirty-two breast carcinomas were studied retrospectively using formalin fixed, paraffin embedded archival tissues on which S-LI and S-flow had been obtained originally. Percentages of tumor cells positive with PC10 and 19A2 correlated well (r = 0.736, p < 0.0001), although the mean marking index for 19A2 was lower and closer to reference measurements than the mean PC10 index. Correlations between PC10 or 19A2 vs. S-LI, S-flow or DNA ploidy (DNAI) were significant in a group of 64 tumors obtained between 1988 and June 1992, and poor in another group of 68 tumors obtained between 1985 and 1988, suggesting deterioration of stainability with prolonged storage. Discrimination of faint staining from negative nuclei was difficult on PCNA stained sections. Carnoy fixation did not improve results over those fixed with formalin. S-flow and S-LI predicted relapse-free survival, but PCNA indices did not. We conclude that PC10 and 19A2 immunostaining of formalin or Carnoy fixed archival breast cancer tissue correlated with reference measures of proliferation only in cases of short storage periods. Although statistically significant, levels of correlation were too low to use PCNA indices for prognosis.

High proliferative rates demonstrated by bromodeoxyuridine labeling index in breast carcinomas with p53 overexpression

The protein p53 is a product of a suppressor oncogene. Mutations occurring in 13-15% of breast carcinomas are associated with p53 stainability within nuclei and progression of the tumor. We determined the extent to which p53 abnormality was associated with proliferation by measuring p53 immunohistochemically with a polyclonal antibody and monoclonal PAb1801 in invasive carcinomas of known S-phase fraction (SPF) assessed histologically by bromodeoxyuridine incorporation. Results with the two antibodies always agreed. One of 20 low, 2/18 midrange, and 9/17 high SPF carcinomas were positive for p53. P53 positivity was also related to other indicators of aggressiveness including size of primary tumor, nuclear and nucleolar size, and estrogen and progesterone receptor content, but relationships between p53 and vascular invasion and lymph node metastasis were not found. We conclude that nuclear p53 accumulation is more closely related to proliferation than to invasion and metastasis, and that it identifies some but not all breast carcinomas with high proliferative indices.

Full-load expansion technique and preliminary clinical application

For accelerating the inflation process of soft-tissue expansion, a continuous inflation protocol regarding pain as the criterion of overinflation, the full-load expansion technique, has been introduced. It is carried out by restricting persistently the pressure in the expander near the pain threshold in a state of dynamic equilibrium between the infusing rate and the skin expansion velocity with a simple and practical device. This inflation is neither at a uniform infusion rate nor at a constant filling pressure. Nineteen expanders in 13 patients were inflated following this protocol. Their inflations were fulfilled in 5 to 20 days, depending individually on their anatomic regions, total volumes of infusion, areas of the overlying skin, and patient susceptibilities.

[Effects of guifu dihuang pills extract on rabbit IgG accelerated mouse nephritis induced by nephrotoxic serum]

The effects of Guifu Dihuang Pills extract were observed in rabbit IgG accelerated mouse nephritis model induced by nephrotoxic serum. The results showed that this preparation could increase serum albumin, reduce urine protein, serum urea nitrogen and total cholesterol in serum, and improve the histological lesions in kidneys. The effects of Guifu Dihuang Pills extract in dosages of 0.3g/kg and 1.2g/kg were similar to those of cyclophosphamide 0.015g/kg.

Whole body and splanchnic leucine, phenylalanine, and glucose kinetics during endotoxemia in humans

To examine the whole body and splanchnic tissue substrate handling during endotoxemia, an intravenous bolus of endotoxin was given to six healthy volunteers during primed, continuous infusions of [1-13C]leucine, [ring-2H5]phenylalanine, and [6,6-2H2]glucose. Whole body protein breakdown, based on whole body Leu and Phe appearance rates (Ra), increased in response to endotoxin given at time 0 (RaLeu 77 +/- 2 mol.kg-1 x h-1, t = 0 h; 88 +/- 6, t = 4 h; P < 0.05) (RaPhe 39 +/- 2 mol.kg-1 x h-1, t = 0; 46 +/- 3, t = 4 h; P < 0.05). Splanchnic amino acid balance (Bal) increased (BalLeu 7 +/- 4 mol.kg-1 x h-1, t = 0; 21 +/- 5, t = 2 h; P < 0.05) (BalPhe 3 +/- 2 mol.kg-1 x h-1, t = 0; 16 +/- 4, t = 2 h; P < 0.05) and can be accounted for by increased splanchnic uptake (Rd) of Phe and Leu (RdLeu 21 +/- 3 mol.kg-1 x h -1, t = 0; 37 +/- 7, t = 120 min; P < 0.05) (RdPhe 10 +/- 3 mol.kg-1 x h-1, t = 0; 24 +/- 5, t = 120 min; P < 0.05). Splanchnic conversion of Leu to ketoisocaproate increased with endotoxin administration (0.7 +/- 0.6 mol.kg-1 x h-1, t = 0; 8 +/- 3, t = 360 min; P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Prenatal diagnosis of Sanfilippo disease type C using a simple fluorometric enzyme assay

A new fluorogenic substrate, 4-methylumbelliferyl beta-D-glucosaminide, was used for the assay of acetyl CoA:glucosaminide N-acetyltransferase in chorionic villi, cultured villus cells, and amniocytes. Optimal conditions for the assay and the ranges of enzyme activity were established for the various types of fetal cells. This simple fluorometric assay provides a reliable method for early prenatal diagnosis of Sanfilippo disease type C which is more convenient than current methods using radiolabelled substrates. The method was applied to amniotic fluid cells and fetal fibroblasts from an at-risk pregnancy in which an affected fetus was diagnosed by two-dimensional electrophoresis of glycosaminoglycans in the amniotic fluid.

Determinants of accrual of women to a large, multicenter clinical trials program of human immunodeficiency virus infection. The AIDS Clinical Trials Group

To determine factors influencing the enrollment of women in a large multicenter human immunodeficiency virus (HIV) clinical trials program in the United States, we analyzed enrollment and demographic data of the AIDS Clinical Trials Group (ACTG) during the period 1987-90. Women comprised 6.7% of 11,909 ACTG participants enrolled in 1987-90. Women entering ACTG trials were significantly more likely to be white (48.5%) and less likely to have ever used i.v. drugs (22.6%) than U.S. women reported to have AIDS (26.5% were white; 51.0% had ever used i.v. drugs, p < 0.0001). In a multiple logistic regression model, specific attributes of individual trials did not influence enrollment of women with the exception that trials that targeted asymptomatic persons had greater enrollment of women. There was wide variation among research units in the percentage of women enrolled (1.0-37.5%), and evidence of significant regional variation in the ability of units to recruit available women. Units with female principal or coprincipal investigators had more than twice the percentage of female enrollment as units headed by men (10.8 vs. 5.3%, p < 0.001). Enrollment of women in a large HIV clinical trials program was low and appeared to be influenced more by demographic and geographic factors that attributes of specific trials. An apparent positive influence of female leadership on the enrollment of women warrants further study.

New cyanocyclines from a cyanide-treated broth of Streptomyces lusitanus

Organic extracts of Streptomyces lusitanus, the producer of the anticancer antibiotic naphthyridinomycin [1], were found to contain two additional compounds active in an antibiotic screen. As with 1, these reacted with NaCN added at the end of the fermentation. One of the addition products has been named cyanocycline B [3] and is derived from N-desmethylnaphthyridinomycin [4], while the other has been named cyanocycline C [5], and is derived from the hydroquinone 6 of 1. Cyanocycline C is unstable and was characterized after conversion to the dimethyl derivative with CH2N2 in the presence of TFA. The implications of these metabolites for the biosynthesis of 1 are discussed. A third new antibiotic, cyanocycline D [8] was isolated from the cyanide-treated broth and proved to be an artifact in which the oxazolidine ring had been opened by cyanide. The potential relevance of the formation of 8 to the reaction of 1 with DNA is also discussed.

Clinicopathologic analysis of 60 cases of basal cell carcinoma

An analysis of 60 cases of basal cell carcinoma is reported. Among the 60 patients were 29 men and 31 women (1:1.1). Their ages ranged from 22 to 88, with an average of 58.8 years. The courses were from 2 months to more than 20 years, with 50% being less than 5 years. The head and face were the main sites involved. The etiology, clinical appearance, pathologic classification, and clinical therapy of the basaloma are discussed briefly. To minimize the patient's psychological burden, and according to the low rate of metastasis, we suggest that the tumor be designated basaloma or basal cell epithelioma rather than basal cell carcinoma.

Transfection of the mullerian inhibiting substance gene inhibits local and metastatic tumor-growth

Mullerian Inhibiting Substance (MIS), a gonadal growth factor important in sexual differentiation, has antiproliferative activity against several human carcinoma cell lines. In this study, we examine the effect of MIS-transfection on the growth characteristics of Chinese hamster ovary (CHO) and human ocular melanoma (OM431) cells, compared to wild-type lines and a CHO line transfected with a noncleavable, inactive MIS mutant. MIS-transfection inhibited proliferation of CHO cells in double-layer agarose, tumor spheroid, and murine subrenal capsule assays, as well as growth of CHO and OM431 cells in pulmonary metastasis studies. These results anticipate further study of targeted gene therapy of certain human tumors with MIS gene constructs.

Micromanipulation of chromosomes in PTK2 cells using laser microsurgery (optical scalpel) in combination with laser-induced optical force (optical tweezers)

An optical scalpel and optical tweezer have been combined to perform intracellular microsurgery and micromanipulation in vivo. When only laser microsurgery was performed on metaphase chromosomes, the dissected sister chromatid fragments drifted off to either the side of the spindle or completely off the spindle. At anaphase the fragments separated and the two arms generally moved to their respective daughter cells. When the chromosome arm was cut during anaphase A and B, the distal chromosome fragment separated from the rest of the chromosome and moved toward the pole, following the proximal chromosome fragment. Distal chromosome fragments laser-dissected during metaphase were held together throughout anaphase using the optical trap. Optical trapping of dissected chromosome fragments during anaphase A and B inhibited movement of the chromosome fragment to its pole. As a result, the trapped chromosome fragments were (1) incorporated into the opposite daughter cell, (2) lost in the cleavage furrow during cytokinesis, or (3) eventually incorporated into the correct daughter cell. These results indicate that optical traps are effective in holding laser-dissected chromosome fragments throughout mitosis. This new tool should be useful for studies on chromosome movement and cell genetics.