On cloning human beings

The purpose of this paper is to show that arguments for and against cloning fail to make their case because of one or both of the following reasons: 1) they take for granted customary beliefs and assumptions that are far from being unquestionable; 2) they tend to ignore the context in which human cloning is developed. I will analyze some of the assumptions underlying the main arguments that have been offered for and against cloning. Once these assumptions are critically analyzed, arguments both rejecting and supporting human cloning seem to lose weight. I will first briefly present the main arguments that have been proposed against cloning and I will argue that they fail to establish their case. In the next section I will evaluate some of the positive arguments that have been offered supporting such technology. This analysis will show that the case for cloning also fails. Finally, I will maintain that because critics and especially supporters of this technology neglect the context in which human cloning is developed and might be implemented, their arguments are far from compelling.     

Sister chromatid exchanges in Down syndromes and normal human beings.

The BrdU-Giemsa method was used to analyze the frequency of SCEs in a group of five Down syndromes and in a group of five normal human beings. In total 25 second mitoses were scored for SCEs in each individual. Although Down syndromes exhibited a tendency to have higher rates of exchange than normal human beings the analysis of variance showed that these differences were not statistically significant. On the other hand, significant differences were observed in the rates of SCEs between individuals within each group. This variability may reflect inter-individual differences in the efficiency of the mechanisms involved in the production of exchanges. The frequency of SCEs in blood cultures in probably the average of the rates exhibited by two or more lymphocyte sub-populations with different sensitivities to BrdU. Hence, the variability in the rate of exchange between different cultures of the same individual probably arises by changes in the percentage of cells in the second mitosis deriving from each lymphocyte sub-population.     

Two claims about potential human beings

It seems that at conception something is formed which, due to its genetic make-up, has the potentiality to develop into a full-blown human being. Many believe that in virtue of this potentiality, this organism, the human zygote or early embryo, has in instrinsic value which makes it wrong to use or produce it merely as a means to some end, e.g., some scientific end such as to produce embryonic stem cells. Against this it is here argued, first, that it does not follow from the fact that something has a potential to become a (fully developed) human being that it already is a human being (in a rudimentary sense). In fact, a human being begins to exist no earlier than a couple of weeks after conception, at the stage known as gastrulation. Thus, even granted the questionable assumption that something has instrinsic value in virtue of being a human being, the zygote will not have intrinsic value. Secondly, the value an embryo has in virtue of its potentiality to become a full-blown human being can only be instrumental, a value as a means. But of course it cannot be wrong to treat that which has merely instrumental value as a mere means or instrument to some end.     

Determination of selenium and iodine in human thyroids.

This study focuses on the determination of selenium and iodine in human thyroids. The glands were digested using nitric acid in a microwave oven. Selenium was determined by inductively coupled plasma optical emission spectrometry (ICP-OES) using a new sample introduction system consisting of a reduction system coupled to a hydride generation nebulizer (DHGN). Iodine was determined by using the Sandell-Kolthoff procedure. The detections limits were 0.2 ng/mL and 0.3 ng/mL for the determination method of selenium and iodine, respectively. The amount of iodine in the whole gland was 3.44 +/- 1.11 microg/g. The lowest iodine level was 2.34 microg/g and the highest 5.21 microg/g. The lowest selenium concentration for a single sample was 505 +/- 51 ng/g and the highest 1495 +/- 204 ng/g depending on the fraction of the gland selected.     

A frequency-dependent finite-difference time-domain formulation for induced current calculations in human beings.

The finite-difference time-domain (FDTD) method has been used to calculate SARs and induced currents involving whole-body or partial-body exposures of models to spatially uniform or nonuniform (far-field or near-field), to sinusoidally varying EM fields, or to transient fields such as those associated with electromagnetic pulses. However, a weakness of the FDTD algorithm is that the dispersion of the tissue's dielectric properties is ignored and frequency-independent properties are assumed. Although this is permissible for continuous-wave or narrow-band irradiation, the results may be highly erroneous for short pulses, in which ultra-wide bandwidths are involved. In some recent publications, procedures are described for one- and two-dimensional problems for media in which the complex permittivity epsilon * (omega) may be described by a single-order Debye relaxation equation or a modified version thereof. These procedures based on a convolution integral describing D(t) in terms of E(t) cannot be extended to human tissues for which multiterm Debye relaxation equations must generally be used. We describe here a new differential-equation approach that can be used for general dispersive media. We illustrate the use of this approach by one- and three-dimensional examples of media for which epsilon * (omega) is given by a multiterm Debye equation, and for an approximate two-thirds muscle-equivalent model of the human body. Based on a single run involving a Gaussian pulse, the frequency-dependent FDTD [(FD)2TD] method allows calculations of SARs and induced currents at various frequencies by taking the Fourier components of the induced E fields. The (FD)2TD method can also be used to calculate coupling of the short (ultra-wideband) pulses to the human body.     

Dengue virus replication enhancement in peripheral blood leukocytes from immune human beings.

Dengue 2 virus replication in peripheral blood leukocyte cultures from 10 of 13 Asian or Polynesian subjects with actively acquired dengue immunity and two of three infants with passively acquired dengue antibody. Only 2 of 11 cultures from nonimmune infants or children supported viral replication. This study establishes a parallel in the biological behavior of human and simian PBL with respect to the immunological dependence of dengue virus replication in vitro. Elucidation of the mechanism (or mechamisms) regulating growth of dengue virus in leukocytes from immune hosts may contribute to an understanding of the role that virus-leukocyte interactions play in the pathogenesis of human dengue illness.     

Chronic toxicity of rare-earth elements on human beings

Blood analyses for rare-earth element (REE)-high background regions in South Jiangxi show that the population averages of many of the biochemical indices deviate markedly from normal values in the normal region. These deviations are thought to be caused by prolonged intake of REE through food chains in view of that the toxicity of other harmful metals such as Pb and Cd can be neglected because of their insignificant amounts in the environment. In comparison with the normal region, blood biochemical indices abnormal in the REE-high regions are manifested as low total serum protein (TSP), albumin, β-globulin, glutamic pyruvic transitanase, serium triglycerides, and immunoglobulin, but high cholesterol. These deviations may be related to the REE concentration and composition of food chains, and are sex dependent. Certain blood indices (such as TSP) of different age groups in the LREE-high region indicate that the influence of REE on males is a one-way irreversible process, whereas females show a strong ability of restoration.     

Glucosinolates in the human diet. Bioavailability and implications for health

The glucosinolates are a large group of sulphur-containing glucosides found in brassica vegetables. After physical damage to the plant tissue, glucosinolates are broken down, by the endogenous enzyme myrosinase, releasing glucose and a complex variety of biologically active products. The most important and extensively studied of these compounds are the isothiocyanates. Glucosinolates can be degraded or leached from vegetable tissue during food processing, but thermal inactivation of myrosinase preserves some intact glucosinolates in cooked vegetables. Once ingested, any remaining intact glucosinolates may be broken down by plant myrosinase in the small intestine, or by bacterial myrosinase in the colon. Isothiocyanates are absorbed from the small bowel and colon, and the metabolites are detectable in human urine 2–3 h after consumption of brassica vegetables. Isothiocyanates are potent inducers of Phase II enzymes in vitro, and they have been shown to increase the metabolism and detoxification of chemical carcinogens in vitro and in animal models. Some of these compounds also inhibit mitosis and stimulate apoptosis in human tumour cells, in vitro and in vivo. This second effect raises the possibility that in addition to blocking DNA damage, isothiocyanates may selectively inhibit the growth of tumour cells even after initiation by chemical carcinogens. Epidemiological evidence supports the possibility that glucosinolate breakdown products derived from brassica vegetables may protect against human cancers, especially those of the gastrointestinal tract and lung. To define and exploit these potentially anticarcinogenic effects it is important to understand and manipulate glucosinolate chemistry and metabolism across the whole food-chain, from production and processing to consumption. This revised version was published online in June 2006 with corrections to the Cover Date.