Morphological features of the deep component of the posterior inferior tibiofibular ligament.

PURPOSE: The deep component of the posterior inferior tibiofibular ligament (PITFL) was classified by type in this large-scale cadaveric study to provide basic information that will help elucidate the mechanisms underlying ankle joint posterior impingement syndrome. METHODS: This investigation examined 100 legs from 49 Japanese cadavers (mean age at death, 79 ± 11 years; 58 sides from men, 42 from women). In classification, absence of an independent fiber of the deep component of the PITFL were classified as Type I, an independent fiber of the deep component of the PITFL was classified as Type II-a, an independent fiber of the deep component of the PITFL with bundles of fibers connected to the posterior intermalleolar ligament (PIML) was classified as Type II-b, and an independent fiber of the deep component of PITFL with a band shape connected to the PIML was classified as Type III. RESULTS: A deep component of the PITFL was present in all specimens. An independent fiber of the deep component of the PITFL was present in 37 legs (37%), connecting to the deep component of the PITFL and PIML in 26 (70.3%). Several types of deep component of the PITFL were identified: Type I in 63 legs (63%); Type II-a in 11 (11%); Type IIb in 12 (12%); and Type III in 14 (14%). No significant differences were seen between the right and left legs. Type I male were significantly more than Type I female (p < 0.05). Type III female were significantly more than Type III male (p < 0.05). CONCLUSIONS: Strong relationships exist between the PITFL and PIML.

Morphological features of the cervical ligament.

PURPOSE: The purpose of this study was to clarify the morphological characteristics of the cervical ligament (CL). METHODS: This study examined 80 legs from 40 Japanese cadavers. The CL was classified by the number of fiber bundles. The morphological features measured were fiber bundle length, width, thickness, and angle with the sagittal plane. RESULTS: The CL was classified as follows: Type I, the CL is a single fiber; Type II, the CL consists of a superficial fiber and an inferior fiber; and Type III, the CL consists of a superficial fiber, intermediate fiber, and inferior fiber. Type I was seen in 15 feet, Type II in 57 feet, and Type III in 8 feet. In comparisons of morphological features within each type, significant differences were seen in fiber bundle length, width, and angle between superior fiber bundles and inferior fiber bundles of Type II and Type III. In comparison among types, the total fiber bundle width was significantly wider in Type II and Type III than in Type I, and the angle was significantly smaller in Type III than in Type I. CONCLUSION: The results of this study suggested that each type may have different sub-talar joint control functions.

Morphological features of the posterior intermalleolar ligament.

PURPOSE: In the present study, the posterior intermalleolar ligament (PIML) was classified by type using large-scale cadavers to provide basic information to help elucidate the mechanism of ankle joint posterior impingement syndrome. METHODS: This investigation examined 100 legs from 49 Japanese cadavers (mean age at death, 79 ± 11 years; 58 sides from men, 42 from women). In the classification method, an absent PIML was classified as Type I, a PIML with one fiber bundle (attachment to one place) was Type II, a PIML with two fiber bundles (attachment to two places) was Type III, and a PIML with three fiber bundles (attachment to three or more places) was Type IV. Furthermore, according to other adhering tissues, they were further subdivided and classified by type. RESULTS: There were various types of PIML: 19 (19%) Type I; 24 (24%) Type II; 23 (23%) Type III; and 34 (34%) Type IV. A PIML was present in 81 legs (81%). There were no significant differences between men and women and between left and right sides. CONCLUSIONS: The complex relationships of the PIML with the surrounding ligaments and tissues are considered to be among the factors that make interpretation of imaging findings difficult.

Morphological features of the bifurcated ligament.

INTRODUCTION: Damage to the bifurcate ligament is one of the most difficult injuries to diagnose from imaging techniques. A probable reason for this is that the morphological characteristics of this structure have yet to be sufficiently elucidated. We, therefore, endeavored to elucidate the morphological characteristics of the bifurcate ligament through a large-scale study involving numerous specimens. MATERIALS AND METHODS: This study included 100 feet from 52 formalin-fixed cadavers. The bifurcate ligament was classified into three types: presence of both calcaneonavicular ligament and calcaneocuboid ligament (Type I); absence of calcaneocuboid ligament (Type II); and absence of calcaneonavicular ligament (Type III). Morphological characteristics of the bifurcate ligament were determined by measuring fiber bundle length, width, and thickness at the center of each ligament. RESULTS: This classification resulted in 68 Type I feet (68%), 32 Type II feet (32%), and 0 Type III feet (0%). The calcaneonavicular ligament was 20.8 ± 2.9 mm long, 4.9 ± 1.2 mm wide, and 3.8 ± 1.1 mm thick. The calcaneocuboid ligament was approximately 10.5 ± 2.7 mm long, 4.7 ± 2.4 mm wide, and 1.5 ± 0.6 mm thick. The bifurcate ligament was located deep under the extensor hallucis brevis and extensor digitorum brevis muscles in all specimens. The calcaneal origin of the calcaneonavicular ligament was situated deep under the interosseous talocalcaneal ligament in all specimens. Two sides were identified in which the calcaneocuboid ligament was located deep under the dorsal calcaneocuboid ligament. CONCLUSION: Such variations and positional relationships were suggested to be factors complicating the diagnostic imaging of bifurcate ligament injuries. The present study results will likely form useful basic data for diagnostic imaging.

Short-chain fatty acids induce tissue plasminogen activator in airway epithelial cells via GPR41&43.

BACKGROUND: Chronic rhinosinusitis (CRS) is a heterogeneous chronic inflammatory disease generally divided based on the presence or absence of nasal polyps (NPs). One of the features of NPs is excessive fibrin deposition, which is associated with down-regulation of tissue plasminogen activator (t-PA) in NPs. As t-PA is expressed in epithelial cells, and epithelium is readily accessible to topical therapies, identifying compounds that can mediate the induction of t-PA would be a potential new strategy for the treatment of NPs. OBJECTIVE: The objective of this study was to determine whether short-chain fatty acids (SCFAs) can induce t-PA in airway epithelial cells via their known receptors GPR41 and GPR43. METHODS: We performed immunohistochemistry (IHC) to determine whether receptors for SCFAs, known as G protein-coupled receptor 41/free fatty acid receptor 3 (GPR41/FFAR3) and GPR43/FFAR2, are expressed in nasal tissue. Primary normal human bronchial epithelial (NHBE) cells were stimulated with different concentrations of SCFAs to test induction of t-PA, which was analysed by expression of mRNA and protein. Mediation of responses by SCFA receptors was evaluated by specific receptor gene silencing with siRNA. RESULTS: Immunohistochemistry study revealed that airway epithelial cells expressed GPR41 and GPR43. Acetic acid, propionic acid, butyric acid and valeric acid significantly induced t-PA expression from two- to tenfolds. The strongest inducer of t-PA from NHBE cells was propionic acid; cells stimulated with propionic acid released t-PA into the supernatant in its active form. Gene silencing of GPR41 and GPR43 revealed that induction of t-PA by SCFAs was dependent upon both GPR41 and GPR43. CONCLUSIONS AND CLINICAL RELEVANCE: Short-chain fatty acids were shown to induce airway epithelial cell expression of t-PA via GPR41 and GPR43. Topical delivery of potent compounds that activate these receptors may have value by reducing fibrin deposition and shrinking nasal polyp growth.

Anatomical study of the inferior patellar pole and patellar tendon.

In this study, detailed investigations into the shape of the inferior patellar pole, the site of the patellar tendon attachment, and the length and course of the patellar tendon were performed with the aim of examining the anatomical factors involved in the developmental mechanism of patellar tendinitis. The investigation examined 100 legs from 50 cadavers. The inferior patellar pole was classified into three types: pointed, intermediate, and blunt. The attachment of the patellar tendon to the inferior patellar pole was classified into two types: an anterior and a posterior. The length of the patellar tendon was measured from the tibial tuberosity to the inferior patellar pole. The pointed type was seen in 57% of legs, the intermediate type in 21%, and the blunt type in 22%. Twenty-one legs were the pointed type, as well as the anterior type. The patellar tendon was significantly shorter with the posterior type than with the anterior type. The blunt type also had a significantly shorter patellar tendon than the pointed type. In legs that were both the pointed type and the anterior type, the inferior patellar pole and the proximal posterior surface of the patellar tendon impinged during knee flexion due to the posterior tilt of the patella, suggesting the possibility that this may induce damage. With the posterior type and blunt type, on the other hand, the possibility of strong tensile stress on the tendon fibers of the posterior facet of the inferior patellar pole was suggested.

Gender differences of muscle and crural fascia origins in relation to the occurrence of medial tibial stress syndrome.

Although women reportedly have a higher prevalence of medial tibial stress syndrome (MTSS) than men, the possible role of gender-based anatomical differences has not been investigated. The aim of the present study was to investigate the presence of gender-based differences in the range of muscle attachments along the entire medial tibia, the proportion of muscle attachment at the middle and distal thirds of the medial margin of the tibia, the structure of the crural fascia, and chiasm position. The specimens were 100 legs of 55 Japanese cadavers. Statistical analysis was carried out using a chi-square test to compare anatomical features between the sexes. The flexor digitorum longus (FDL) had a higher proportion of attachment to the middle and distal thirds of the medial margin of the tibia than the soleus (SOL; P < 0.001). The proportion of the SOL attachment to the middle and distal thirds of the medial margin of the tibia was 33.3% in men and 72.5% in women (P < 0.001). The soleal aponeurosis was not observed in any specimen. In all specimens the FDL formed the top layer of both chiasms. These results suggest that the higher prevalence of MTSS reported among women may be the result of gender-based anatomical differences.

Novel scoring system and algorithm for classifying chronic rhinosinusitis: the JESREC Study.

BACKGROUND: Chronic rhinosinusitis (CRS) can be classified into CRS with nasal polyps (CRSwNP) and CRS without nasal polyps (CRSsNP). CRSwNP displays more intense eosinophilic infiltration and the presence of Th2 cytokines. Mucosal eosinophilia is associated with more severe symptoms and often requires multiple surgeries because of recurrence; however, even in eosinophilic CRS (ECRS), clinical course is variable. In this study, we wanted to set objective clinical criteria for the diagnosis of refractory CRS. METHODS: This was a retrospective study conducted by 15 institutions participating in the Japanese Epidemiological Survey of Refractory Eosinophilic Chronic Rhinosinusitis (JESREC). We evaluated patients with CRS treated with endoscopic sinus surgery (ESS), and risk of recurrence was estimated using Cox proportional hazard models. Multiple logistic regression models and receiver operating characteristics curves were constructed to create the diagnostic criterion for ECRS. RESULTS: We analyzed 1716 patients treated with ESS. To diagnose ECRS, the JESREC scoring system assessed unilateral or bilateral disease, the presence of nasal polyps, blood eosinophilia, and dominant shadow of ethmoid sinuses in computed tomography (CT) scans. The cutoff value of the score was 11 points (sensitivity: 83%, specificity: 66%). Blood eosinophilia (>5%), ethmoid sinus disease detected by CT scan, bronchial asthma, aspirin, and nonsteroidal anti-inflammatory drugs intolerance were associated significantly with recurrence. CONCLUSION: We subdivided CRSwNP in non-ECRS, mild, moderate, and severe ECRS according to our algorithm. This classification was significantly correlated with prognosis. It is notable that this algorithm may give useful information to clinicians in the refractoriness of CRS before ESS or biopsy.

The twisted structure of the human Achilles tendon.

The Achilles tendon (AT) consists of fascicles that originate from the medial head of the gastrocnemius (MG), lateral head of the gastrocnemius (LG), and soleus muscle (Sol). These fascicles are reported to have a twisted structure. However, there is no consensus as to the degree of torsion. The purpose of this study was to investigate the twisted structure of the AT at the level of fascicles that originate from the MG, LG, and Sol, and elucidate the morphological characteristics. Gross anatomical study of 60 Japanese cadavers (111 legs) was used. The AT fascicles originated from the MG, LG, and Sol were fused while twisting among themselves. There were three classification types depending on the degree of torsion. Further fine separation of each fascicle revealed MG ran fairly parallel in all types, whereas LG and Sol, particularly of the extreme type, were inserted onto the calcaneal tuberosity with strong torsion. In addition, the sites of Sol torsion were 3-5 cm proximal to the calcaneal insertion of the AT. These findings provide promising basic data to elucidate the functional role of the twisted structure and mechanisms for the occurrence of AT injury and other conditions.

Morphological features of the inferior fascicle of the anterior inferior tibiofibular ligament.

In this study, the inferior fascicle of the anterior inferior tibiofibular ligament (AITFL) was classified to provide basic information to help elucidate the mechanism of ankle joint anterolateral impingement, and the morphological features of each type were compared for the purpose of clarification. This investigation examined 100 feet from 52 cadavers. The AITFL was classified into four types according to the presence or absence of the inferior fascicle and the positional relationship between the AITFL and the inferior fascicle of the AITFL. The morphological features of the AITFL that were measured included the fibre bundle length, fibre bundle width, fibre bundle angle, and the distance between the joint levels. A distinct, independent inferior fascicle of the AITFL was identified in 15 feet (15%). There were no significant differences in the morphological features based on differences in the AITFL classification. Therefore, these findings suggest that the presence or absence of the inferior fascicle and the difference in the positional relationship between the AITFL and the inferior fascicle of the AITFL are less likely to be involved in impingement during ankle dorsiflexion.

Conventional tumor markers are prognostic indicators in patients with head and neck squamous cell carcinoma.

We tested for squamous cell carcinoma-related antigen (SCC), carcinoembryonic antigen (CEA), ferritin, immunosuppressive acid protein (IAP) and sialic acid in the serum from 247 patients with head and neck squamous cell carcinoma prior to therapy. Significant correlations were found between IAP and tumor size, lymph node metastasis, and clinical stage (P<0.0001, P<0.001, and P<0.0001). Also, sialic acid and SCC were also correlated with tumor size, lymph node metastasis, and clinical stage. Moreover IAP, sialic acid and SCC were strongly associated with survival rate (P<0.0001, P = 0.0230 and P = 0.0159). A multivariate Cox proportional hazard model demonstrated that being positive for IAP was an independent predictor for patients with H&NSCC (P = 0.0115). The results indicate that IAP, sialic acid and SCC are useful as prognostic factors.

Characterization of cytochrome b(5) in the ascidian Polyandrocarpa misakiensis and budding-specific expression.

A cDNA for cytochrome b(5) was cloned from a cDNA library of buds of the ascidian, Polyandrocarpa misakiensis, by a hybridization method involving a digoxigenin-labeled cDNA probe of human soluble cytochrome b(5). The nucleotide sequence of the cDNA for the ascidian cytochrome b(5) (Pmb5) consisted of about 1,800 base pairs including 5'- and 3'-noncoding regions, and a coding sequence of 405 base pairs. The amino acid sequence of 135 residues deduced from the coding nucleotide sequence exhibited 54% identity and 76% similarity to chicken cytochrome b(5). A highly conserved amino acid sequence was observed in the amino-terminal domain of 96 residues containing two heme-binding histidine residues. The putative soluble form of the recombinant Pmb5 expressed in Escherichia coli was purified to homogeneity by column chromatographies on an anion-exchanger and gel filtration. The purified Pmb5 showed the typical absorption spectrum of cytochrome b(5) with an asymmetric peak at 556 nm and a shoulder at 560 nm upon reduction with NADH and NADH-cytochrome b(5) reductase. The low temperature spectrum of the dithionite-reduced form of the protein contained the split peaks at 551 and 555 nm, this spectrum being very similar to that of mammalian liver cytochrome b(5). Expression of Pmb5 in the ascidian was examined immunohistochemically with a monoclonal antibody against the Pmb5. Apparently high level expression of Pmb5 was found in the developing buds, but the levels of cytochrome b(5) in the parents and juvenile adults were very low. This is the first report on the characterization of Pmb5, and the increased expression of Pmb5 in the ascidian.

Anti-interleukin-8 monoclonal antibody reduces free radical production and improves hemodynamics and survival rate in endotoxic shock in rabbits.

BACKGROUND: Although high levels of interleukin-8 (IL-8) have been found in patients with sepsis and a monoclonal antibody (MoAb) against IL-8 has been successfully used in some animal models of inflammation, no specific therapeutic agent against IL-8 has been tested for the treatment of sepsis. We studied the effects of a MoAb against IL-8 in the treatment of endotoxic shock with a prospective randomized rabbit endotoxic shock model. METHODS: Twenty New Zealand white rabbits were anesthetized and divided into four groups: normal, anti-IL-8, control-Ab, and lipopolysaccharide (LPS). Anti-IL-8 and control-Ab groups received a MoAb (immunoglobulin G, 3 mg/kg) 5 minutes before the LPS injection. All groups, except the normal group, received a continuous 20-minute infusion of LPS (500 micrograms/kg). The normal group received NaCl (0.9%) rather than LPS. RESULTS: The 7-day survival rates were 100% for normal group, 80% for anti-IL-8 group, 40% for control-Ab group, and 0% for LPS group. Compared with the LPS group, anti-IL-8 rabbits had a smaller decrease in mean arterial blood pressure (p < 0.05) and increased urinary volume (p < 0.05). Anti-IL-8 rabbits had lower plasmatic levels of IL-1 beta, less free radical production (p < 0.05), and a higher survival rate (p < 0.01). CONCLUSIONS: IL-8 plays a significant role in endotoxic shock, and IL-8 blockage results in attenuation of the hypotensive and tachypneic effects of LPS, reduced free radical production, and an increased survival rate after lethal endotoxic shock.

Ultraviolet light and mitomycin C induced sister-chromatid exchanges in fibroblasts from patients with retinoblastoma.

Ultraviolet light and mitomycin C (MMC) induced sister-chromatid exchanges (SCEs) were investigated in 6 diploid fibroblast strains derived from 3 patients with deletion 13 and retinoblastoma, one patient with a hereditary form of retinoblastoma, one patient with trisomy 13, and one normal control. Two fibroblast strains with del(13)(q14q22) showed a significant increase in SCEs compared to the control after UV and MMC treatments. In contrast, cell strains with del(13)(q12q14) and trisomy 13 did not show increased SCEs. The frequency of SCEs in fibroblasts from a patient with autosomal dominant retinoblastomas (no deletions) was significantly increased by UV, but not by MMC. The results suggest that cell strains with different deletions of chromosome 13 have different SCE responses to UV and MMC inductions. The cells with del(13)(q14q22) may have a DNA-repair defect.

Effects of a medicinal herbal liqueur, "yomeishu", on post-operative gynecological patients.

We administered 20 ml of Yomeishu (YMS) twice a day before meals for 12 weeks to 50 post-operative patients in gynecology and then inquired into their subjective 20 symptoms (sense of fatigue, insomnia, headache and heavy headedness, appetite, stomach-ache, abdominal inflation, vertigo, lumbago, etc.) The YMS group showed a significant improvement on 14 items compared with the control group. On the whole, a great improvement was observed in the YMS group with serious subjective symptoms as well, and there were significant differences for general condition, sense of fatigue, and coldness in extremities.

[Antibiotic resistance of clinical isolates Streptococcus pneumoniae].

Streptococcus pneumoniae is a major pathogenic organism of community-acquired bacterial pneumonia as well as otitis media and bacterial meningitis. Recently penicillin- or multiply resistant pneumococci have been isolated worldwide. In this study we examined the susceptibility tests of 11 antibiotics with the total of 63 clinically isolated pneumococci, using a broth microdilution method. Most of pneumococci were isolated from respiratory specimens. According to NCCLS standard, all these pneumococci were classified as follows: PCG-susceptible S. pneumoniae (PSSP, MIC < or = 0.06 micrograms/ml), PCG-intermediately resistant S. pneumoniae (PISP, 0.12 < or = MIC < or = 1.0 micrograms/ml), and PCG-highly resistant S. pneumoniae (PRSP, MIC > or = 2.0 micrograms/ml) were 45 (71.4%), 14 (22.2%) and 4 isolates (6.4%), respectively. Forty-four percent of isolates from children under 10 years and 29% from outpatients were PISP or PRSP. Resistance to erythromycin (EM) clindamycin (CLDM) or minocycline (MINO) was significantly recognized, but not correlated with that to PCG. On the other hand, the resistance to beta-lactam antibiotics were correlated with that to PCG. Seventeen isolates (27%) were resistant to two or more antibiotics among PCG, EM, MINO, ofloxacin (OFLX), and sulfamethoxazole-trimethoprim (ST). In pneumococcal infection, we always have to pay a careful attention to susceptibility test before we choose antibiotics.

[Hepatic arterial infusion chemotherapy using totally implantable reservoir in liver metastases in colorectal cancer].

Hepatic arterial infusion chemotherapy using totally implantable reservoir was performed for the treatment of liver metastases of colo-rectal cancers, and the therapeutic effects, side effects and complications were evaluated. Reservoir catheters were implanted into hepatic artery via gastroduodenal artery during operation. Mitomycin C (MMC), adriamycin (ADM), and 5-fluorouracil (5-FU) were used as chemotherapeutic agents. Eleven cases of H1 (metastases in one lobe only), 7 cases of H2 (a few scattered metastases in both lobes) and 12 cases of H3 (multiple metastases in both lobes) were treated intermittently with one-shot administration of MMC or ADM (A-group). Ten cases (H1: 1, H2: 2, H3: 7) were treated with intermittent one-shot administration of MMC or ADM following two-week continuous infusion of 5-FU through infusion pump after operation (B-group). In 5 of 10 cases of B-group, serum CEA level fell below the preoperative level, and the tumor size regressed in 3 of those 5 cases which were evaluated on the basis of CT scan. But no remarkable change in CEA level or tumor size on CT scan was seen in A-group. No particular side effect such as leucopenia, liver dysfunction or gastroduodenal symptom was noted except one case developing multiple gastric ulcers and pancreatitis in B-group. Five cases (25%) showed obstruction of catheter and 3 cases (14%) evidence leakage of chemotherapeutic agents in A-group. Three cases (30%) in agents in A-group. Three cases (30%) in B-group displayed obstruction of gastroduodenal artery beyond the tip of catheter. Median survival time of both groups (A, B) was 6 months and 12 months, respectively. The treatment seemed effective for the improvement of serum CEA level and tumor size, and there was a tendency toward prolongation of survival time in B-group.

[Transcatheter arterial chemoembolization and selective hepatic arterial infusion using totally implantable reservoir].

Transcatheter arterial chemoembolization (TAE) and hepatic arterial infusion using totally implantable reservoir were performed for the treatment of liver metastasis of colo-rectal cancers, and their therapeutic effects, side effects and complications were evaluated. Eleven cases of H1 (metastasis in one lobe only), 7 cases of H2 (a few scattered metastases in both lobes), 12 cases of H3 (numerous metastases in both lobes) were entered into the study and underwent TAE 45 times. Gel foam, Ivaron and Lipiodol were used as embolic materials in combination with chemotherapeutic agents such as mitomycin C and adriamycin. Serum CEA level was decreased less than 50% of pre-TAE level 20 out of 32 (61%). The tumor size was regressed in 25% of TAE cases which were evaluated on the basis of CT scan. Abdominal symptoms including abdominal pain, nausea and vomiting and fever, leukocytosis, elevated GOT, LDH and bilirubin level were seen after TAE therapy. Median survival of H1, H2 and H3 cases were 21 months, 8 months and 4.5 months, respectively. Another 21 cases (H1, 5 cases: H2, 3 cases: H3, 13 cases) of liver metastasis of colo-rectal cancers were treated with selective hepatic arterial infusion therapy using totally implantable reservoir. Reservoir catheters were implanted into hepatic artery via gastroduodenal artery under direct vision at laparotomy. Mitomycin C, adriamycin and fluorouracil (5-FU) were used as chemotherapeutic agents. No particular side effect such as leukopenia or liver dysfunction was noted. Median survival of H1, H2 and H3 cases treated with arterial infusion were 4 months, 9 months and 9 months, respectively. Median survival of TAE cases and arterial infusion cases was 10 and 6 months, respectively. Thus, the survival rate of cases treated with TAE was better than that of cases treated with arterial infusion.

The outcome of pregnancy and prenatal chromosomal diagnosis of fetuses in couples including a translocation carrier.

In order to evaluate the relation between chromosomal translocation and the outcome of pregnancy, 50 couples were examined. Subjects consisted of 35 couples that included a reciprocal translocation carrier; 13 included a Robertsonian translocation carrier and 2 included a carrier of a mosaic reciprocal translocation. The reasons for performing chromosomal examinations were mainly infertility and abnormality of neonates. The rates of miscarriages and neonatal abnormalities in prior pregnancies were significantly higher than the birth rate of morphologically normal newborns. The presence of a translocation is closely related to reproductive failure because of the chromosomal imbalance. However, prenatal chromosomal examination after the 15th gestational week in subsequent pregnancies revealed that almost half of the fetuses showed normal karyotypes and only 12.8 per cent of the fetuses showed a chromosomal imbalance. Many chromosomally imbalanced fetuses are spontaneously aborted before amniocentesis. The risk of chromosomal imbalance is relatively low in prenatal diagnosis, but partial trisomies of small rearrangements tend to be preserved.